FOREWORD151:}H. E‘W’i} R Ill
The reportrep-curt enon the Kapsabet-PlateauHtiphiihCI—Piiiiflfiu areaEtFEEI continueseenlt'tjttL;e.~~ toten the north:mr'tft workaxe-iii ttjz'eattigalready publishedDLthttt-éhii'ti in aLl report enon the KerichoKer‘jenn ILFL‘U.area H".(F. W. Binge,Binge. 1962)[tifilt amtand tnto the eastL‘zt‘i‘f; workwurk madetttade L—Lt'zttlehavailablee in .1a reportrepttr't neton the KakamegaHahamega are:area (A.I':"'t. Huddleston,HLtddtefitttn. 1954).litiét. Itit L‘t'et'rzcovers partpm; ofHi the NyandoKimmie: exeescarpment,flr'pment. whichtt'hieh formsteem:~ the northernHerzhet'n wattwall erof the KavirondoK.1‘~f§'t‘fidt"¥ 1411i:gulf egraben,when. the northernttttt'thet'n part atof the Largelarge L'tttettmtvolcano Timterer.Tinderet, part tilt"of the [ahtrrmhte—et'ut'ereephonolite-covered Uasinl-.hhh‘t {ltGishufihtt plateau JT‘HJ.and, enon the west,H. e541. :1:an are:area fioft ;1ate.ier'.tancient !'ttt.;}~.'e.rocks, frtettttincludingfi-tng gt'ttztitea.granites.
theThe wuthernsouthern hurtpart efof the .tr'e.1area Km.is ittttter'frmtimportant mas i'.it eezttttinacontains Mitt-eerieMiocene hthelake tietje-e-iw.deposits, including “FUCHUH'IE‘Q.limestones, whichwhieh :1r'eare seenween onmt httthboth the Ltuh-rtthi'ttWHdownthrown amtand upthrownL11'JHH'UWZ‘! mjelewsides ul'of the[1 e WynmieNyando equipmentescarpment T-L'tfaultsflli‘w $.11land gitegive Lta measure['I'atletwLil'L.‘ ett'of the dirzphteertteh:displacement et‘of the with“:surface enon uhiehwhich the htftji.‘:t3["|ir~lsediments u'et'ewere htidlaid elem-”it.down. Clthes'Other "-"-;‘.Ta:5'-];ti."twater-lain éettimehtrnsediments :teeare flexposedjfimcd at places[tftteea flalongung the edge 01'of the tthtrittttétehphonolites “atof the 'L':-.air'_-Uasin {'iimiztt.Gishu, ht;but hatehave me.not te;yet tleittettyielded HLtTItL‘tCnlsufficient t'ttmhitfossil evidence tnto behe LtE‘L‘lJ.‘L1t“'T'j-accurately timedated.t.
Thehe lavasham-e1: ttl'of 'Iimter'etTinderet tireare netof e't‘-I":-I_:_tuel'.:hleconsiderable LitLe:ewtinterest ;-..«as thej~they tat-etudeinclude nepheiimtewnephelinites .ttt-e;and melilite-bearingItteléléte—het‘n'tng tjtpeu.types. BitLiidBouldersflf'h ttl'of LLH'hL‘H‘IttIJtecarbonatite are.are z'ettul'tettreported t'r'ttrttfrom fragment-.15fragmental ‘t't'n'ietttiievolcanic met-wrocks em.on the HULJThsouth witteside ut'of the mountain,rtmtmtzttn. ;t!t:tand :'Iit inis .r'e;1.-m1;=.';1~|ereasonable it:to inferir‘I'eI' Th1itthat the tuletm.‘volcano HLEIL‘QTI'H1"L:1.'{"_!"U-:."."-:_‘”'!.il._“~'.;superstructure overlies a e'ttihL‘-['.L15.11a:carbonatite eet'.t:e_centre.
Inh": the western't't-L‘H'LL'I'E'] partpet"; ofrat the areaate: there areLtI'L‘ exposuresexptwtr'ea ofn.“ olduht' lavashue-a ofenr' the Nyanzian“item-1111 System,Rtatem. mehsuch :t'~as further wuth.south, :1".in the Kibigoricieei': ere-.1.area, L‘UI'ELtti":contain get-Itj-henrfttggold-bearing LtLtttetrquartz veins.'-.;_’EIt*~. 3"».A mint]small JIHULLEHamount ef'of 5105c}gold huhhas heeztbeen recoveredI'eetttel'ett tmrttfrom mehsuch withveins i-‘tin {hethe HL‘FLiih-RRL‘HIL‘ITIsouth-western partgm" nl'of the.the :J.|'-..'.Ll-area. 'Uih:One netof the veins'a'eim hmhas elmalso g'iettéettyielded the euieitimcalcium ttme.~;rete.tungstate, aehee'fi:e.scheelite, buthut it Wmwas ll".in only.only ita HE'IELtHsmall FIJI";part hiof the tetnvein ‘.h;':tthat there umwas Lift}any rmtttht:notable eerteezttrtttiettconcentration.
theThe Tinderet'tfneeze: Elsi-eerievolcanic rocksr'neh~. :_::'eare height}notably em'heuutettcarbonated :=_.“.Ltand nutterwater e.tetgfngemerging E'l't-zt':from them isin :ttil‘mzr'nhretfmineralized. U‘t‘tt:One amine.spring, :LLat KehewKeben, wheretU—J'Etere Eher‘ethere :35;is '_ta h-"ée'ttjr-ty'p-eVichy-type tt'attertwater, my;was tnrfor t:a time-.!'"|‘!:. usedelamj .Has .|a “Ct-.1-spa. TheELL etlcttarea anas tta whole-.*.-tU.-e is:~ well-watered.+‘C:I""~‘-.;I'..!CL|- ::.'!tiand water-supply1"..1.L‘:—*~.‘.l.-.,;:"'.- presentsI‘- Chan little problem.
Nairobi, WILLIAM PULFREY, 28th March, 1961. Commissioner (Mines and Geology).
I if.CONTENTS{331551313 PAGE
Abstractih'fiti'uct
I-Introductionl-—i;1[:'L“-L€L:-.:[iwn :imiand Henna]General Informationinlai‘u Exam:
II-PreviousIi "P CE'jiii-LJE. -’.._.i;.-Geologicalfi_|r:.t;.;i_-;al! Workek 3
III-Physiography 4 (1) Topography and Drainage 4
(2) Erosion Bevels 5_.PI
. ..--.---. .I""_,. - '-.-'--'=' .. .-_"' .-.. I. -.-. IV-Summary of the Geology~iLa.|..'_._.. and“.1“ xGeologicalELK} '._.fl'.'.~.12! History1'".'ihT_L.‘-| 'L ofLI. theLi's-.1. Area.33:11" . 8
V-Details of Geology. . 10
|. 1. BasementE33:=-;-.:!TWC-“:=f Fig-ENE]System 10Il'
. 1. 1;..‘._ .- : . ..I 1 (1)L I ,- Pelitic:--:;;L._~., andLam; semi-peliticr.Lr1.-.-i‘.u:. gneisses 10_.I
... uh!r""|'(2) Migmatites=_.'.-a!1g:1.---.1:rc-' _ -.. i .. 12
='_-.'(a)fi Biotitefan-m: rmwnntfr-QELmigmatites. 12I_ ..- . 'l ' I - . I. ---_'|; ':. --\. --: -.-u 1 -_- I1 (b)9 HornblendeH0; ”Land; |-.!._'_!:':.~!migmatites: Hug 13I-\.I
... (3) Granitoid gneiss 131
‘- ' ml ' 'r -- -' 1 -- III - I' . . ,w. .1 ..-. I ..I 2._. RocksJ-hh.=.~f.r, LEIderivedfittl fromHum t.he1.1L. Basementri;~¢t.1n:._i1 hkSystemfiLfl _: 14|._L -1 .Jr'.... :. -.-. _:.-. (1)'.':| Migmatiticail-r'.‘.T.I'."l..~ll.'.".:'_ granites":JILJJH 14
3.5 NyanzianHymn-Hun SystemEy'fiium 14
4.hr. IntrusionsLlLTLIEIUnh...... ' ..._I'into11:3,-.- thetn:'_ Precambrianl}.:w_L-.:.1..1..1n_ .-.---'--: RomaRocks.._'... 15
II](1): “-v-ialjMajorfla' EE!§C'"‘:-l"i._':.":Silica-rich IntrusionsEliii'liflif‘li'ifi 15.-:
I-_ (a)m] TH:The MaragMaragoliflfl gz'F-mitcgranite 15I '1. =.'.-"'J.‘I(b) Wur'thNorthernfin grazim‘iisrriicgranodiorite 16i'. 1 {r}(c) Emnhri'nSouthern granodioriteg:'£1=1c:‘:1:'{'ri'i_L¢: 17J I22).(2) BasicEmit IntrusionsIt'ltt'ilsirjrns 17 {:3}(a) Highly metamorphosed1-1:: amurpimacd basichymn;- hug-2143intrusivea rocksmar; 17 {:21}(b) DoleritesDUE-Erika am’}and mctametadoleritesfiolcriifl 18 ir'](c) Amphibole-"-.ni=;2=ji:l*~u|c ray-ska;rocks . 19 ii}(i) HornblendeHm'nhlez'ujc EpidioritesEpicéim'jtca 19 iii}(ii) Actinolite-"’h-:T§!1IT‘3[;IC: EpidioritesEi;'1id§nr:itt‘h~i 20 (3){3r Pegmatitesl’nrgmeltimi andali'tiil GiantGian-i Quartzflunr‘tr VeinsElfin 20
5.'i-J'I Tertiary.I cr'tmr}: . 20 H(1)]' MioceneMieccne ECLiimcmHSediments 20 in}(a) LimestoneLimflmne _ . . . 22 if?)(b) BleachedElm-.Chfl'i tutuffsfi'a; and.and “miMudstonesLuismncfi 22 {I}(2) PyroclasticPyt'fliiiaflic rocksHui-v.5; Hfof TinderetTiruftrr'ct .. 23 (3){'3} 'i'crlian'yTertiary Lavas{LEE-1L5 25 in”:(a) ClassificationCialraflificztmm 25 (b)NJ} PlateauPlatCflu Phonolites.i’JH‘H'!L:ulI.‘-.::.-: . 26 (i){i} DistributionDistributifln 26 {is}(ii) CmmpnCompositionfiition 27
. CONTENTS-( Contd.) PAGEl] -‘11l’._i J
(c) Lavas of Tinderet{21.13121 27
1| 1"2'. J11!(i) PIE-[LPhonolitic111.1117. nephelinites11L; ‘ 11'. 1111-11 28_- A.
.;Jl::l(ii) Phonolitic{31111111 1J1l11F11: melanephelinites‘ILJ11‘11151JJ'111'LL51C 28_. |. (iii)1 Nephelinites‘11-;111L'1'1111 lL'“1--:and11111 melanephelinites111111 L'1[FTDHC' JI"11'1 11'3“? 28
(iv) Melaphonolite ...... 2911132-1”:- . 1.-I. .11: -_-' (v) Melilite nephelinites.1L’‘13-‘11. "l.'._|1.’1.‘-1 and1.1.113 melilite‘1'?!“3J111I1.‘ melanephelinitesF.1l‘l111'ICJIHI. 111121. . 30..--1-1
(vi) Melilitite 31'..1I_.1..1[..1-r1.1|..:ll
—. .1
_1'
—-1.
_1
_.
1r"
F1.
2‘..-
-1_
-.3
1...- ....
-—r
I1.-11mI (vii) Basanites. . 31IJJ 11.11.1r11l(d)1 Phonolites'}'.11 .-111.of ' Tinderet1-11.1211:'11 1 31:1."
6.1 Metamorphism"-1.‘=..-.‘l 1 -- 1“ 1-1-1'.-1'-1!1 of= 1 ‘ the1'-1--L' Basement1‘11!-.‘.“-‘.-13.'1.ETA-.21-'. . 11 System" .- . . . 31'1'1 7. Structure. . 34 (1) Basement System 34 '1 - I 1:- .1.1-1- (2)— Faulting.' '1. I;. . 36
'I. I -.~ VI-Mineralll1. .I-.I Deposits[I.- fill-h.111 37-1--1 . -1.. 1.!. 1-11-1.Gold.11.1 . 37'I '11 .; ' ‘1. :- . ~11 2.-_. Scheelite1‘1. II11.1.1 _ 38 .; 3.. 1 LimestoneL.' .11.?“ -1.'.' _ 39'I'1-l . . . -..'.I.- ."- 1.- 4.1 Brick-claysI..E': 1.|‘111—..1 '- 39 5. Building-stone 39
.J' 6..- Mineralized water 39 7. Water-supply"'h'|'\-||_ 40
VlI-References 43
LIST OF ILLUSTRATIONS1.1.1113'111‘1-5111'5 111111
[35; .- :1 1' '.'i 1. .1 1"" 1'1'1 I 1-, -- '1 g 1 i-".1-._ 111- 1')q -_-.1 - I Fig. I.-Drainage-'\- ' _—1.- and.-1 1- PhysiographicJ I _:.I. "I1. Units'11 _"'1 of'1- theI1. -1_ Kapsabet-Plateau.~"|1.'. . '2" ! I.|. -1_ 1....1area... 4 ~1._I-_ - -1. -- -~1 11 .n1- ._-i 1 --.-1 11-1 1| -1 .-__1r-1§ 1 E-,_-_- .'__ 11111.1 1_---1 _ 11.-1-1_-_.-1. Fig. 2.-Sketch-.--“‘11-—' I map11. to- show=- - relationship1111.1..1-'| II..' of peneplain._ '11.:..-1-1|.J|. bevels,'1.-~1.'l.|1.._'-._ Miocene.-1|'11_-1_|_ 3‘111_'.:1.I.-1..".sediments and.11.. Tertiaryi1. 1 '=‘ volcanic~1‘..1'1 .11. rocks.1.11.311 ...... 6I I
”I ..' 1-1 1 ...... I_ ' _..1; 1-1 ' _. -1 ..-1 .—.- -1. -1. Fig. 3.-Structures:31: 1—.-.- 1.“ in-- thel'I1-1 BasementJjLi‘kl J-1-'"1 System:‘1T'1I1-r I rocks1-'-_"‘113"1-.l'|of 1.:1'11.the Kapsabet11's....111‘h...‘ J. area1.1:-..-.'1 33"- 'H.
film-F 1 1'1-.--1i- - -1-.--1I "'"1 _-1'_r _..;- rim-15'- -1- -.h 'r-L_-11|:-.-11 : -.I-1. . Tulle: '.'_.._-..:_1;I.-I_T.. ' 1.. -:.' I- 1..'I Fig.- l-1_. 4.-Stereographic"1—-'1-1-' --l-.' ll1— projection| '1-IJ'1-1-1-1- J'1.-- of11: poles-'-.".1 toUL- foliation,111- 'LJ....J1-J LI.and' lineationJ..!!'1.'1'1.-.-.'. 1: forJ11 the-.:1'1. rocks11:».."1 1 . 11-1 -..I ”-11 1-11 " -..-1- -1 1-1 --..- .- ----1...-1-§ km 1. - - 1 of'~'- theI-II'H- BasementI-r- 5'" - I-:|- System35.}1L: in the11"11 areaLI. 1-1-I1-1 around.I. '1_"1.-'i.'-1. - KapsabetI- '\-I.:-\‘I‘:.\"\-l'\—-H‘h' ...... 34 I1. - - - - _- .I- __ '--: .__ .1. .1. 1-1.1 1_ 1. -. 1. -1; '|-. " 1; | .- 1. . .1_. .I ..-,_-..-11..' ' . ' .. - ._ ._ .' Fig. 5.-StereographicMILL-1LL-J'“ .. .1. projection:1.'1.-!1_I_1.'1.' I of-. polesiL-h'lL- to'11] foliation,!=.||{5.lI'-1.E'l-1 and:11. 1111.. lineation|:.-'-1-.1|.'-.-'.r'1 forJLJ. theL::1. rocks.-'1;_:_'1~." 1 . .; 1 1 ..- - - - -= - -. . - - -. -1-1 1-1 -.-1 ; - -. . -..-1 J .- -_-1- .. . of1- the1: Basement.1111... .11I System511m- -1. in the-.1-area around.11.11...... 1L.1:111Kabiyet1 . 35
-1 .- - - ' . "II '1 - . -! " . 'J' . - Fig. 6.-Positioniil‘lfi: :J of'1." boreholes1 LEI'L'.I1_."" inI the__1:1: Kapsabet-PlateauEH1. “:1.“- :"_L ..- lr1_-: - HIM—11'.area 41
MAP--..-."L3 115‘
1|.' - 1- -1 1 1-1 -1 - __.i'r _ 2'" t ."11 " , .: 1'-"\1 .-1. -_ I - I - - Geological1—1|'|—I1.I map1i of'1- 1 the Kapsabet-Plateau-“'_ :5" '_ I 1 1.1' : area,.' 1.; KenyaEma. 11-1: (Scale231. 1. 1- :125,000)I__'.;.- ..At end
! ABSTRACT.iflalhilii
Theltla.'. ”3.1.1report.. L.|._’.‘--._I.l"|'._3'*-.describes:- .. the-'_,..I... area...... -. c... immediately....1r.".....|!..!-:!‘- F. ' to...-.~. L1.the'.. r~:.‘nL-_I-south.. .1of Eldoret.r:..-.:4..~.:l. It-.L comprises somemrm.‘- 1,200-“~--.'.._Ul: 3-3.3.1.-.square...-.. I‘m-m.miles,.1... boundedL-*.I.!L1m_1::-.i. - .1 h.by. 131::the-. cc..t...--.-.-.equator...... _-...H‘.and latitude|.-....-.. -: 0°'- 30'-...-a!___. N..'3“- and.11-u-.. by'0». longi-mug.- ...' . ' H -' ... "' "- ' L-.'..1' :"l ..a tudes'.l.."._|'-.."‘ ...-H35° H”00' .1;-|'...-and ..'...35° 30''!'-'l 1:.E. PhysiographicallyFlt-Hr'11:.'E:FT‘-lpl"1'l""“l' 3 theL... next:area umcan be(I: divided into a broad - - band.-.I-...._.l ofL._ undulatingL:.-1~..EL-... , ..1 .13;- hills...JanLi: of.31 ' Basement15.!..~.L-.1.-.3n-.!_.._. Systemmam?“ rocksr..*l...::.-. .._I. in..‘._'_ the‘..;L.'... west,~.=.-.:~..~..._ the-l.. -‘~ UasinT-._.._J_'-L|l' Gishu{Jim-1 - lavaLn. - plateau..-._.}-.-.1.L~...9LL.. ~..u-to the.1..:.. 1m-north-east,_...... -.....-.1.. _.mdand Ln:the'. “mud-cu.wooded_. 1".'_!highlandsl1:__*:.|.*n...-,_~ u;of.' the..I -..- 'T_Tinderet'..“...-.?:-..:._.' ._.-.volcanic-..1.....I-....f..___. _ mass-.mgr.» ..to ...
thein; MI.:-LJ'.south-east.
.
.
.l
-.
a.
r' .-
r"_1______,. -.: . '. -.--... '..-._...... _.'. . '.._ -.2-..
.-
_.-
'\-l
“f-
F...
_.- . The'..‘lr. :L-lrocks of the1.1.: Basement['l.1-.~..r‘-.!L..I.. .‘h-.‘~-=.::‘.System are highly- H- .- gm...granitized...... gneissesmean... and migmatites.-.1..:.‘!1:-.=..=.-*-. i—. . _— --. _ -. , .._.] . i..' . _ . I. _ ”F ' . 5 " I ~" ... . -. .I: .'.- . They1"3} have'1‘“. beenbad. 1.11:“..‘L‘Liinvaded byl". L-.l'|'..‘doleriteH1. Jar“dykes and.-l twolul- HI'E‘ILLIsmall bodiesITWIJSL'H ...-Ilof granodioritez;!.'.:'.l.3||._:ii.}l'.-=.f -l1".'..fand, -. ... ' . ,. . .1. :-in the..:.: m:l.=__'1—~..-._~.1.south-west, r--.by ..Icthe rh-i'mainfl H.1I..:.sl-Maragoli.. gran-.12:granite.. ;.- PatchesF-‘trhrw .1.of' ..‘.1:altered3....' volcanicachd.. fir.:.. ._..‘:L'mrocks.- preserved near the margin of -..'..-.the granite-;:_ -'3.L .55.as fault-blocksEiiillll—hitjuka .1":are :‘-.'«:-.:1:T.-':i.assumed 1-."to 171-:be NyanzianHmnwi age.EL"
MioceneMun-3'1” lake-beds1.1hC-1L‘.1~» ALL”occur in1.] the1.1:: south,HI'..'L..!'.. L‘I‘~n._‘l-.:!1'|overlain bym. .=.:_=£!-.=:1.::.11'._‘r~:agglomerates ._..of Tinderet,Lid-:1. whichAmt.- are.. L‘ in'.1 turn.LJ 1 overlainMPH...” byH the-..-C plateau1‘.:..“.-.L. phonolites[‘2 1.15.1”...3. extending.311-.‘:.[“-.L1-.;‘!g from1mm the'..“.F: north-east.Iqiil—Liahz. The1.-'.-.: last:.-.- are.. .‘ h!_."-._-._I._‘CL.L‘.|succeeded by'3').- the”...‘? remainder: .n-l..L.'-'LCH:: H]of the.l'. volcanic'-'."!I....1l-! L Ha‘Li;.C[‘:‘LC‘.sequence ._l'.at Tinderet,1::'l-...:‘.i|._".. including.|"I|_i.."..l.1:; a. variety1.5.: .‘ of: under-saturated[INS-..‘: ‘..lL" :1..L"|Lj basicI‘D-h: lava|.l"'1 :1.””~types.
Goldbut...!.J and«.11 scheelite-....*.r:.:.':.:-. depositsLicpma-Jn.' ..'. .1:.:are. described.=.:r:.-.-.:l .l“..-n...:
I GEOLOGY OF0E“ THE KAPSABET-PLATEAUKsifSABE“l“—?L5L“I'E.ILE AREAILRFI’L
T'II I-INTRODUCTIONl—i'T-II'TRL}“CELT.“Tlfifi' AND. I. “TL E} GENERALTL; ETT‘II' ITZFL . INFORMATION
AT~‘TI. g.geologica'!IIl-LT-g'TITLTn'! reconnaissanceI'L:-.TLTITTIIT.._I:IT-T~T-.TIT:I.TLI LTTT'of theIg-._ ‘I-Ii".ii..south-west-II.—--TT quarterI....:I:TT;-~IT LIIof L¥-..-L:rI:--degree T?IL':LT.sheet F34 (KenyaIT'iTILIL'T. Colony,IIL' IIITIjI- IT'_T-.T-ITTTTTLTTI"corresponding'r-Liiil“.'~- with.-I::f. I'IiTILT::T.sheet 103:,T IT-E'of theTiT.LT DirectorateL3H: L'IIiITT-L'I ofI‘T' Colonial'1 ‘T“T'~'T“I'-lj Surveys)“Lilli—565‘ was“T' ”T LTeI.carried LILL'Lout LiieiI'Igduring tiTIILT.the periodELTT'iLTL.’ “.‘-IL'ITI--..IT.'.TII'.'.T.-TT.November, 1956,‘ITI'TTIi'i LIL5to July,iI_I.ij.T 1957.JT3"'.7, The'i'LII: LLTLTLIarea :II'Iis boundedhIT-Ilf‘liizf-Iii byi'TIT' EEILTthe equatorLTL!!_.I.5_'-.LI.TT andIITIIJ latitudei;--iIL';LILT LI0° FL'i30' N."TI' ..:TII'.iand longitudes1ITLTIITIIT".LI-.iI:T.T~-I .‘_‘—T35° [TI-LI"00' "I‘.-iand Iii-T35° _5-.30' E.Li. and:nII L'comprisesT”‘L'"-"T“T¢'-'-“T' II._TIIITI:some 1,2001.1a" squareILITTI.:T.I.ITI.'- miles.TTT. i-~ Itir includes:TTILTi I=.iLTT- partsiTIT TTT.T -'I.T.'L'of ILTILIthe Nandi“TII'IIT-TIE District,'[TIEIIHT . Uasin.I Gishuf."-T5'.iT I District'I'.“.T-LIiLL'l and._I:1.I_i Nakuru“TILT.I.TLLIILI District,“L'JAII TIT. a'llII 1 withinT-.TI-|iII.TI theT'TTLT RiftETLIIT. VaUey‘I'“:iTIi'iLTI Province,F-‘T T.T- .I.TTI-T.iand partI:TLLI'TI of the‘-'...T-:.T KerichoL‘LTLSIJLTI‘W DistrictDiairici I'TIfof LitLT.the Nyanza.II'TI'L .I.-. Province.‘}T'§.3“‘rfi—““ -.
InLIT. theIiIL- fieldi—IL-iLi information.TIiL LIL wasTIIILTI plottedPiIT'IITL:Li. LiTTLLIiTIdirecdy onm airL-LI photographs,BLIIZ'ILTLTT ‘-.".Ii ~ atI”. 1.the”TE T'éTILTisCaJle!. of . approximately 1: 30,000, produced by the Royal Air Force in the early part of 1952. The.'hLT informationIIILLT-T'IT.T.L‘L ITrT wasIII Ii-I then'IiIITn transferredT..T'I.TI'LIT.-.Tr-:'.:I to.._I fourLUI'I pr~liminaryPrtiii‘LTTIIITtLITTI plots,[I'.I'II‘LII. '.“TII'II'ITTNorth : A.36TIM—4:153: IX..TIL IIII'Ii. N.E.,“‘Ji N.W.,“TUTTI-"I’. S.E.ELL LIITILLand S.W.,.‘II‘IIT".. LIIat aTIL TI:I.'TT.-'=.iL:Tscale IT.TIof 1:.5:.T'53I!.'50,000.{IT-I Form"linesL-L'T-rTI —3..TI--.-.T-: wereTIT-.Iir-TLI taken..IiLL-ITI from:: T.TT.: WarTT.-"III Office[.'_ - sheet~i'LIE:IT.'-I'. North“‘III'.'T-IT.IT A.36/X'. 3‘.” .‘TL {if-45L(Uasin f“};T~'I..I_IGishu) at.'II theTIIT_ scale-L'".TL|.- of 1:1122:.TLTET'I.25,000, beingi'II'ir modified:TT--.'_T=-L'.“I.fiLL'L where'-'-'.T:..ITT: necessaryTII:L"I3T~'-I~I.L.TL for“L“L'TI' _-_;TIL-LLIIT:greater accuracy.TLLILT.I.LI.=T TI. Fina'li'iT‘i.I reduction_.IJLI--5I. toIL'I a sca'leT~:.-'L.T'I'-LEL- suitableTII:I'iT.:.'.Ti._ forfIITT printingLTI:Ti_TTIti:TI;-';_ wasTI-TI'I-III carriedL'LLIITILTL outTLIT.=.‘. photographically.;:LITII.T_'~'__TTIT.I.T5IT. '.LT ijI'.
AboutJ-.iTIIT:IIIr ITITIIL'Tone-thirdTiT.TiITTLL L‘!i_-".i'_TI'.'TE.1I"TL'iI’-_I_of the area liesiIL:'~I '-.'IIiT':IIT.Iwithin LLLL'the WL‘LIILi:Nandi ETILIIJLLIJSpecia'i Area,.T'TLITLTLL. '.'IITIILJand isLII administeredILiITTrTIIITIiTiT.LIIII fromL-E'ILIIII Kapsabet;L‘LLTLI.‘~“IJ '_‘L'. L- LLDapproximatelyfiL—IJ ‘I.-_iI. LL' '.'_'.“ I .L.L‘-.T'half is.‘5 'T-...-occupied'JFHE'L- 'by5M5 EuropeanL.'.LT.“TL}TL.-_L_1 LILL.“iTL13_LII_:farm'land, 1._I._watNe_LLLIL“ L'land__ “LL—‘I.tea plantations,TL”: :i.1L|L_'E- whileTiI'I“_-i’:_ theLIiL. remainingItl.iLi!I;J:_3;_ s!xthT=-‘T.L[I is.'T5 reservedI'_T.L'_.:“~II_.'.L forest“J“HHLJTIL 'land.i-.1.I|L1_ OfLL theI.r_I._ 'latterIIT_T.LEF theLILL NorthhLJi'i T.-.TTII'.Land 3LSouthT.II.1'.LI Nandi.“TTJ'L'LnITLii ForestsiTL‘IITLTT-ILI: LTLrTI:are I]'_._lmainlyiifLTI -TLTITIHTi.rTI.I:IT.1confined [LTIto mmmdground belowIiT-LILIJJLL' I‘TEKT—TI'iTI6,500 ‘.“-“TL'T-feet LLETLiand LI-T'nTform aT. marked:TILLIT'ILLLL contrast'.F:'~ to‘I'T theTLLLT Northern“.‘LI'Tr' T'T”TIT':T. Tinderet,“Lu-ETTLLL_'f-LL_ Timboroa,T.““_“‘!“I“"I_“'Ti_ Nabkoi.“TTI'.I'TT“.-.'.I and.LrtLi KaptagatLT'L. {TT.Ig-Tj. Forests“.T—T whichT-I'x'iTIéLi'fI LTLI-‘ITTIIJextend LITITTILTIIfrom 7,500 {LI-:1.feet to1_-.~ L'III:over '-9,000-"3..'!.- LL'TLTL-feet. The’I.—Liv South.‘I'IILLLLT. Nandi"TIL...Lii Foresti I.'I.TL- 1 ReserveELL-TIL-rT-‘L- isT~I aT.-. natural:TILLLLITLL‘I forest{LII-{5:51 LTI'Tr‘Icomposed[..-5'.“!'T-L.| ofIITIT mixed.TTITTTLL'L indigenousIITL_Ti51_TLI‘:-III:~. hardwoods,H.'IITLiTITI-IIIIi-~I theTIILT mostIIII.-.- commonLITIr':'17TT species'T'Ii‘TI':-TT beingT.-TT--I'.CrotonITII.-TIIT: megalocarpusTT-T-. -._-II-' IT_T-.I.T..T_.T.T-'.T whichT-.'T--“T'T.':i'I formsLIT-TITIT-u some5-”“ifi 65{If—- pergTIILzIT cent:.T.-.TTTT-. ofI-T the1.3.LT forest.i-IITTLT-II‘I. There'I'iTTTT-LT is35:. limited-I.TT I'..TL'i demand-..iI.TITIT..TLII::'1 for.II.TIIT timber.EI:T=.TITT of this:iTL varietyT-ITLIriILT‘T-. andTIIILi theTLiTILT forestIII-TILTTI'Il isire almost.LIIT'ITITIILL untouched,I.'.TI' LiiTiTIIITLi. TIT-_IIZILTIITIT'LLI'LLL-Tsupporting a singleILT.TT_25L TIT.:LT..—TTTI:“i.“saw-mill withinT-.I.II.iT-!TTI theTI‘ITIL': :LrTarea. A.f'L 5T..TIT:.Lsma'~li amountTIIITILTT-I_:T.TIIT. ITI'of reafforestationIT-LTLLii“I_T T." isI being“TLTT'TTILT -:.TLLIT'.LIiLicarried out northTT.-5r? TI ofTIT-i' theT'TILI. Kapsa'bet-KakamegaH_.—TI-_T_T.IT~TILL'IT LI-TrIL_:-TI.-.'T.:IT.TICLTITL road.LL‘i. TheTiTII; NorthernEur TTItrzTI TinderetTiITTLiL-T ;[ Forest[-._TIII: :I onLT'Ir_I1‘5,-_-I;TIT.'_F_I_T-.-|TI--,_-III_Ithe other hand isix' extensivelyL':.T-I'.'I.-1TITL'i-ITLII-T exploitedL;5:}TI T-‘.L_'.T.Ii forL‘L'l— timber,LIITII'T-LTI mainly.T-TTITI :TIiT. podo,r”TIT-LII. and.Imi fiveFILLIImajorTI._=_TIIIITI.rT saw-miNingIITTLT-LTIT ITEM-fin: companies.::_T.:TLTTI.rI_IITiLT.I- operateTT-TTT:5T_-. withinTIT. 'T'ITI T; theLiTI; area.T'I-TI_:I Extensivei_.TI'.TIT:T fTI'T. reafforestation“LT-.5 .TT-.TTIII I-T1 schemesII.IT:LT.-.ITT.T.-TI~. are inT-p:progress.-T.TI:T__TL-;-.~.
TheT'TTI- NandiTTIL'LITII'1 SpeciallT~Ir- _T ..l Area.-'TIIIT; occupiesIILIC. !;I_II_T-.. a'.L broadlTTLTIILL ’LT‘I-TLJLtract III’Iof 'land!:.-TTILI along.iIjT-ITIL; theLit: westernTI.T.'r'_T.:-L'i.-.T-.TTTI marginrTTI.1.TT:-T of-:*“ the1!'-I.-:T area"."I_T'.- andITITTL'i includes'I’:- i_.T'..--.T'~' mostiII-TIT ofI'IL theLLELT outcropI-.I_IT"I.'*;‘ of'I‘.?“ BasementdLLI.I:‘I-II_."-‘-. System“‘I_IT'.E-:I'. rocksL'nLIL withinT-...'=_II .1 it.LI”. InI"- the‘:_'l-'-:T northfl'“'“||_' these:L':L2T-.'L_ rocks‘.' ‘_‘IITII are'_LIIIT: weBI.L_|- exposed75L; HIT-I.- inJ:I the'LI'IE hillsLIJiLTI. of'.'_'-L Sorora.““TI“'I.".I"I‘-TT"_'|. L-1.|ITIIL'-Eand Sangalo-“‘_5'_. i‘lg:1“::: as“TI; granite-'like(Think; ."LiI._ tors,'-T.-T'TI'. 'butbut furtherTE".IT.TTI‘TIL. southI-ITTIT.I.[3; theyILL-LT? .IareLT. maskedI .:IT~LL-:' by“'_T- -La considerable-:I_TIITI-I=.=.LI.-IT';LiTi,T thickness‘I'TII-L... .I..T.:~I~ of.. redT.:T.1 soil,: usually'.T.~'."..T-1Ti'-. covered._ -T-TT.i with[“5'1 ant-hiHs. OutcropsT'Ii'i-IECIT'i-T-ilr'I areI:TL alsoTiiHIJI limited,IIT'T..I.':L". L'IIIIland traversing‘Ir.-TI_TTTI-T difficultL-.-'ZI..'TI_.=.'. infIT the'iT. Nandi“‘I.-.TT ForestENE-TILT area,I_TT-'-:_I butiTIT'. the___L_ well-dissected'I'.I_ L LiTITLT'T..I_I.. scarp‘7‘! bordering"IIFUTLiilI-gi the‘LiTT area_lf‘I'TTI toIII" thei.."-LI_T. FTI'L-IILJLL-Isouth again::T.T_;-iI'I_ providesIT:-L'T'--.:LiLT~ good:T. I_TI T._T. Li. exposure..: TIT. [:IT I'LL ITIT.
The'i ...T Nandi,“I‘LLLITI.".T“. relatedITL-iITIILTLi toIT'ITI the:iTII': MasaiTT-'i.L'-:.'L'. andIrIL. similar-.i.TT.I:‘IT.'IIT inirT: appearance,I..T.nT .TLIT:LTT.L'.. haveiT..TI‘-I-.- 'lost:.5LTI the[_I.;_ nomadicILII ,__{_L_ habits..LTII II of-..T.T.T' the.iT.I.'.T latter,“I;_I..1I.:, and...TT-i are'..ITLT 'being.‘TLTLTTI; encouragedL-IIILT: .T.-.._:.TLI' to extendT..TLILTITI.'“ the'ier": arable-. .LLTiI: side.-.._ ofIT their.TT farming,T“:-T.TITI.i at:IL theTI!I:: same'I..:T.'ITI_I: timeIITTI: improvingiT IprITT. "I; the:IIL: qualityLIL;.LiILI.' and'.'..TTILi reducing.TI.-LiLILTiIT.-T_L1 theIj-L- numbersT'ILIITITTT -TTL inIn theirI} I; flocks.LEAF. A.I._ livestock“E'T.'T.T~ 'I'ICLT-“I improvementiITITIpITTI'ITLLTTTITI-T—LIITIT. I:I.T-T:TITTcentre “IILIII:has 'beeniTI.TTLTITI maintained.-TT.I::I.TT.‘-'.'T.L'-TTITL:IT.'i at:Lf BaratonELI-.ITL‘L‘IITTTI foriL'IT manyT'.I.IT.TI yearsT.'LT:-..r~' and.T'I-T.I.: benefits“.'TTIJT'E'IJfiL'T'I both'T.TTI.TI‘IT'1 Europeani“'..TI.T."-[.T-L=:=.TTI and.T=..TTI=T.‘I African..—‘«.'.T. '.IT.T.TIr.- farmers.TL'TITILTL»
RainfaMRLII'TII'“T.LIE is{TI adequateLTT.-:T.iI.TLLILILTIT. LT and perennial{LI-.ttT-LTITTTui. springs~T-:._IT.IITI'nr-:TI- existI:TLFIIL throughout1?:1'-_5L1gj1I.T:.It theLETIL reserve.g-L;Lil—Li Soil_ILJTLLIT erosionLL... is-.._ locallyI'._T.:LI‘I‘ITI.T severeI. ~=:TLT inTIT. regions.TT :LITII. II ofLTIL regularILTgLI grass:T‘L’F'i'T'ITIZ burningL“'!2i'i1ii1§?iiandnLl persistentIII-III IIILTTII overgrazing.L5TI LJITIII'LIZTfITIj
I ..
2“1
The .liurapeartEuropean farms eaveringcovering the aartherunorthern taathiitsfoothi:l'ls elfof 'l'itideret.Tinderet, amtand the plateau land in the nurth-eastnorth-east prasEeproduce wheatwheat. and maize.maize, amtand eattcattlee are rearedreareti tel"for milk and beef. thereThere are eatehsiveextensive ttlt:wattle plantatians,plantations, espeeiallyespeciailily iain the aarth—eeptralnorth-centra:l regiua.region, the bark.bark beingheing praeessedprocessed at.at the Plateau Wattle E'erttpt‘trts-"sCompany's taetaryfactory arton the railss'ayrailway at Bldoret.tluret. 'l'hiaThis towntater: farmsforms the main eerttrecentre farfor the IHurapeartEuropean eammtmitycommunity and is situated arton the northernrtartherrt 'boundaryheuadary atof the area. A.i't smallsmaill arrteurttamount at“.of ttaaflax is grownarea-h hearnear Kaptagat.Kaptagat- UhOn thettte taptop ofat the tit-'ahttaNyando esearprtleat=escarpment, rtearnear the western marginma rgiri atof the EarthNorth TiriaeretTinderet Forest,t-urest. eartditiertsconditions are idealidea'! tarfor area'iagtgrowing tea.tea, and large estates are espatuliagexpanding rapidly-rapidly. Further ss'est.west, am:and at a [owerteas-er 'level,teeel. ealt'eecoffee is producedpredueett whitewhfle at the thatfoot atof the searpscarp suuthsouth atof SoyetReset the major croperap is sisarl.sisal.
The .tfe'ttussiagfollowing table,tahte- taken fromiram recordsreeartis ofat: the t-IastEast AfricanAfrieah Meteorologicalh-tetearetagieal DepartDepart- ment,:t‘ttrt‘tt. illtiatratesiUustrates thethe. rainfal'lrairtl'al] variationsar'tatit'ttt ttCtttssacross thethe. areaarea:-: —
19561 e 5; E: 1957t t} 5 7 _a_ we rage. StationStatttatt I Regiontseait‘ut I TotalTtital Total'I'atat Annual:‘shhuttl = No.him. ofat H i itiel'tes] tittehes‘t rainfallrttittl'a tl }-":":‘.T'i:;years (inches) I (inches) I Average ' tiaehes'}(inches) recordedr earaea
KaptagatKaptt gttt (ForesttFtirei-st Station)Elatitit't} ... . I North-Ht‘st'tlt— 47'964T'9ti 45.71as-r: 48,78Sta-TH 293t} Cti'eastfii Plateau tLCtt‘Jt‘t}-‘Di~;l(Letonyok) .... . I North-T‘s'urth- 42-5542'55 35,8735-3? Bit-3a38,55 a8 east.east Ainabkoisainttlalttii {Hatakt'ii(Nabkoi Forestl-'t'-'_'est Cauttt—South- 4t41'51'51 42-]42'11I 4223-5:42'36 11'. ] Station).Statltir‘t}. east Eldorethidtiret {Its-”it?(Meteorologicaleurutugieai North-Hurt h— fi46.10tti- l t} iii-9?}37,99 r40,60fiitt'flfl 11ll Station)*Stattuttfi.. central:etttl'u Lessos[ease-s tlessus(Lessos Farm)Farm} ' . . {TCFJU'LllCentral ii-ti'trtti’.48,88 434448'14 nth-tit}48'80 h8
Siret (Siret{Strict Tea Co.){30.} .. . South-Htitith— 55,9835-9-3 58,65fihat’ifi 59.31fist-fit 14 certtraicentral KabiyetKtthig.-'et. {Eispettsat‘sj(Dispensary) _ . North-htfitrth— I ithi53,85 52.1851th Sta-5:}56'58 4.1 westWEST BaratonBaratatt (Veterinaryt‘t-"eterimiry Station).Ettatipnt- . West-west- I 59.02fist-t]: I 57,05mpg 58.1255;. 1 3 31:320 eeatru]central KapsabetKapsahet tll‘tistriet(District CtitieetOffice) . West-West— I tat-2:360.25 I 51-2551.25 {ah-3460'84 52:1 eeatralcentral
husttttiSavani thatzetai(Savani Estates)Fsttttes'l - . StJtitt‘teSouth- I :i50,04fl-tl-l I 55'57iii-ii? 57-7457,74 2:;28 "I west‘s't’sfht
‘F* isA little northILUILt‘I atof thethe area.
hut es-‘en the major ram-jg, heeprrte Communicationst_'r.irritriuhieatiuas withinwithin. the area are 't—good,eue-tt but even the major roads become temptirarils’temporarily impassableirttpassahle attet’after heat-'3'heavy rain.rain, the worst'a-‘tirst stretches heir];being Wherewhere the roadst'tJEtti's eresscross auterepsoutcrops atof agglomerateaeglemerate amtand ttitt.tuff. The majormajar routesrautes crossingeresshu; the area.area, all ofat“ metatmetal eror murram etittstrtietiaa.construction, are the Tirtttuir.'t.at-t'-.feleretTimboroa-Eldoret stretchstreteh atof the metamain E‘s‘airehiNairobi-Ugandaligamla that].road, the routertittte tt‘titttfrom Fltltu'etBldoret telto Hapsai‘retKapsabet arttland tit".on tt‘:to Kakamega,Kaitarttega. Ltt'tiiand the tatturoad ti:to KapsabetKapsahet vias-ia LessosLesses and NandiHatttii Hi']ls.Hills.
theThe rai n_‘I KipkabusKipltahus tato Fttieret.Bldoret, with stationsstatiuhs at Kipkabus,Hipkahus. KaptagatHaptaaa1. and Plateau. The eteetrieelectric power-line,[Jtt‘a-tjl'vltt'lti, feeding NairobiT‘s’airuhi tramfrom the [ht-eaOwen Falls hytlren—eleetriehydro-electric seherrie.scheme, traverses the area.area, eaternentering hearnear SangaloSangata amtand leaving seuthsouth atof Kahltei.Nabkoi. r_n.||wu.n. 3IJJ II-PREVIOUSlI—II'RE‘IL' {HILLS GEOLOGICAL{I} EULUGICL’LL WORK“IUR H LittleL.II'.11L geologicalLLLLILLLLLLILL.'LL1 work1L1L'LI1T'1-L'. wasLL-LLLL' carriedLLLLI'iLLL'i outLILIL in111 the11113 areaLLLLLL1 beforeI'LLTILLILLL the111L present_LLI'LLLLLLL.1 survey.LLLIL'LLLLL' .T11L'LThe north-west1:.-:11'111-LL'LLLL'1 cornerLLLI'I1L'I wasLLLLLL crossedLrL'ILLLLLL1 by11-} E.1'1. E.1'1. Walker,I‘LLI'LIELIEI'LLL‘II- a.LI Government1iILIJL1IEL1L1'1'11ILI-IC1IIL geOilogist,LLLLLIfL‘LL'iLL. who,‘ILL'E'IL‘I. after.'ILTI‘LLLT travelling1'1'111-L'L11111Lt from1111111 BlgeyoEILLL-LLL toILL Mumias11.1L1111i'LL'L in111 1903,*11111.1.” mentioned111LL111LLILLLL1 "theL':1L'L typicalILL-'piLLLi graniteLL'LLLLILLL knol~ls1LL1L.L.-|1.LL' ofL11I Sangalo"LLLL.._..LL1 (Walker,[1.1-"11'11LL1'. 1903,11111.1. p.[1. 7).T]. G.{I}. T.'1'- Prior11L'EL'.1.L descri'bedL1L:LL.LI1'LLL! "a"LL. more11'LLLL'L: ordinaryL'LrL111LL-LLL'L' typeIL'LLLL ofLLI' phonOlite131LLL-LLL1'LIILL- with'LLi111. abundant11.1.‘1L11'111111'I'1 spheneLL111LLL1L'L andL.'-.1111 nor1LL soda-amphiboles.ELIILILIiLl-HL'T:”1111.11111L1H . .. .. fromLILL1111 theL'LLLL NandiILIII‘11II1:1T11.1JI District"DILLILLILL from11.11? LLL-11LLLLL1 11'_-.-' LTIII'IILLLLI'L 111 111-3. LI21L11 1.ILLLLI1L1:-'L 13111111101111: 1'111".L1':'. 1111.11. amongLL11 LIL-1L:L specimens‘L1II1C'LLIIII-IL-I‘LLr collected 'by officers of the then Uganda Protectorate (Prior, 1903, p. 239),...1 but1'1LEI. the11':L specimen.LLLLL'L'LILLLH locality,ILL-LLLii'Lj-l theL11L'LL‘ILI12ILiLLLILL-LSigowet Hills,HiIiIL'L isin: unknownLILLL'..;11L_LLL-.IL. to1.1 the1111: writer.LLL.1'1'.LI.L. The111: rockr describedL1L-LL'L'1'LLLLL1 by1"I'L" Prior1‘11'111F more1'L1L'LL'LL closely.JIL‘ILLLL1'LL' resem\J1esLLILLLT'IL1LIILLL the111.1: phonolitic111LLLL1LL1L'LIL nephelinites11Lp11L1ILLI-ZLLLL ofLII'1I this11111: report,L'LLL'LI".. rather.-.L.1I.L1_'1 than-.I.I..11I1I1II1Lthe plateauP1L11LL1J phonOlites.FLLLI'.IIILII'L.--.'_"ILI. As.-’-‘-.L.L aLL member111LLLL-L1LL1' ofLLLI the111: 1947111—17 British-Kenya11. 11: 11- 1LL E7.1}'L'L Expedition,1'..I11.E.I11L'L.111'Ii.1 . R.111. M..5111;Shack~eton-~.L.1L 1L1.-LLL investigatediL‘LL'LL-ti-LLLLLLL1 theLELLL extentL:.‘LL'.I.I1_'._11 andL-.:1L1 dispositionL1i~']1-LL.L'.i:iL'L.L.1 ofL.ILI the11'.LL Miocene.LLILLT-LLJL sediments.L'LL'Li'LILL1L-L‘1b' I111in the111..- regionI’LL-51111". ofL'I SonghorI')LI'1I111IIII"" withL'L'iL1': particularpLLL'LiLLLELLT referenceI'-'._1IIL_11'11_'."|L_1L._1 to111 theL11; Koru1LLLI'LI11'L1 limestone,1i1ILLLLLLJILL. in111 orderL'LI'L1Lr to.'.-'L1 elucidateLL11L'.:1L1'LLLLL theL11LIextentL‘LL1L 1L ofL'L1I post-LLLLLLL'L Miocene.1-11LIL'LLL1L faulting1'_LL1i11I1'11_.I (Shackleton,:511LLL1L1LIL'LLIL 1951,11.15]. p.[1. 363).311.1}. TheI11'.LL mostLL1LL1~L1 northerlyI1II_LI1'.III1I1IL.L'_11-11IL-I exposuresLLLLLLL‘ILLLL'LL describeddLLLL'iILLL'Li faB1".111 just_1L1L11.1L111[1'Iir‘|within theL111: southernL'LLILIL11LI'rI marginLL'LLLI'LLELL ofL11I theLILL area.LLL'LLL nowILLLLL under1:5111Lr consideration.LLLIL1LL1L1LL'L111LLIL- The'1'1'11; map11.11111 accompanyingILLL.1....L1.I.1IL Shackleton's111'LLLLLL1LIL1LLLL1'L reportL'L—LLLLLL'L indicates111L111L'1'LILLLL'LL theLIL-LL EE'LDSLJ'L'L‘LIIL‘LILTEapproximate limits1II1L'LL ofL'LL' theL111; MioceneE11LLLLL1L- sediments,LLL1i111LLLLL. the111:.- volcanic'LLLI11IC'LLLII11C rocksL'L'LL'L1LLL ofLILLI TinderetI1IiL1L1LL'L'L and111111 theLI.1LL plateauLTIILLLLL'LLLJ phonolites,_'L111L.IILL'I11LLL:. andLLI'IL1 suggestsLLLLI'L-‘LLILLL‘LLL positionsLLLLLL'LLILLLLL1IL'LI'for both'L'LL'I‘L1LL11LLthe NandiT'LLLLLLL11I andLLLIL1 NyandoI.‘L~.L.L'..'LL'_'IL"- majorLLILLLLLr faults.L‘ILLL11LLL. The.I.?LL vicinity1.1::111111' ofL'I1I theL1LLL minerall111111L-1111 spring.LL-LLLIL'iL‘LLLr at'LLL Keben,1LLL11LLLIL southLLL‘LLIL11 of111" Lessos,1_LL:L'L:..LL.L..'. wasLIL-'LILL examinedL.L'LLL11'.'IL.LL'L1 in1:1 19441-1—1—1- J_IL_I-11Ifor the'LIL'LL Mines.‘Llir‘L-LLL. and1111L1 {.LLL1L‘ILILLL1.1LLLLLLL'LLLLL-TILGeologic~l Department byi'LL' W.'L‘ILI. D.111. Harverson11:LILLrL-LLLL andE".'1L'1 subsequentlyLL11: LLLLLLILL:111'-. in1:1 194711'1'.1‘IL-'1IL11L-.by W. PUlfrey.111111e1.: InILL.- theirL11LII reportsI'LL‘LLLL‘TLL 1'IL11LbothL doubtedL1L‘LLLI'ILLL1 the1111: possibilJity[LLLLLILi11i111'LL of1.11 economicL: LLLLL‘ILILIL. exploita-LLLLLL1LLILLL- tion' ofI theJ1' .LI I sma1'1LLL'L'LLI.'| limestoneEL'LLLLLLL'LL'LLL: depositsL1-LLLLLLLL'LLL present.[11'L‘1-.ILI.1[]T_. Subsequent51:1 LILLq'LLLILLL visits'LiLiLL. toLLr 111LLthe areaLL1LLLL by1L1: Govern-{ELLL'LLI'L'L- mentLL'LLIL: geologistsE.flLJ1L1E11R[5 wereLL'LLL'L'; madeLL'1LLL1L iniLL 195111.151 when1.111.911 A.L'1L- HuddlestonH LLL1L11L=L1LLI1 investigatediI1L-LLLL11LLLLLLLL1 the111:: nature111111c andLLILL1 extent.'L'L‘L'EL'L .‘1 L of aL1 clayL1LLL_L' depositL1LL;JL1.LLL'L LL-LL.on the:11: propertyLLL'LLLLLLL'I'LLL ofL11 Eastern1-ILLLLLLLLLrL1 Produce111'L2-L1LLLLLL and1.111L'L1' EstatesL-.LLL.LLLLLLL'. LimitedL111111LL-L1 LLLIL'1and .1-1. L}n... in..I 19521 LL whenLL'11LL-I'. L.1_.. D. SandersSLLL1L1LL'LL investigatedIL'LLLLLL' LLLLILLJ aLL scheeliteLL1LL':L11'.L occurrenceL'LLLLLIrLLLnLLL at{LI-i Koyoi-LL'LL-LLL in11'I theL111; LLLL'LILLLextreme south-westLLLLIL11-LL'L'L'LLLL of11'1I the11113 area.LL1TItI1L1LI1LT1I'LIEThe 131.1:latter depositLiIILL_3:‘L!I-'. proved[TLI'LL'L'LLi ofLL1I negligibleLLL1!..L.1"IL extent.LLLLLLL1L'..11"L.1LL1L.In July, 1954,1115-I1III. E.1.'.. P.131. SaggersonSLLLLL'L'L.L:.L1 visitedL'iLLiLL'LL. 111mthe L.':LL.1:Lscarp north1'IL1-I'ILI1I'I1 ofL'LLI Songhor.‘LLILLLILLELLLII' 'LLLILiIand producedILLLL LiLL'L'L:L1 aLL provisionalLLILILLILL'. L’LI'LLL 11111117:map of111 theLSLLI1LL1‘ILLL-1LLILLLPL'LLL1'1LLSonghor-Kapsabet road111111.]. up1.1.121 the1.111: NyandoI‘LLILLLL‘LL1L1 L':.L.L’.'L1.L?IILLLL‘ITL.escarpment. -..L _ The1111.1 area£111.11. toLL1 theL11L south,LLLLIL11. mainly11L.'.Li111.LL-' ini11 theL11LL. Kericho1LILL'LIL‘11L'L District,[JIiLLLL‘LIL'L wasLLLLLL mappedI1LLLLLJLLILLL1 byELL-L F. W.11115. Binge1311191: in11—1 1949.111—151.I'IIII' TheI IILL'III'-' equator1.1.11.1.L1L‘LIL:1 I 1' forms1LI1'TLLLLIII ' 'IL'I" the11LLL—"IL. boundaryI.'1L'LILL1'IL1L11L1 -" -'.' between1"IL.-.L-.L:LE:']LI..'.'1'- . - that1.1.II1L'I1.1I- . area.-.iLILIL-l-- I' and.--1..111IL:.-rl theLI'.'-:_L presentprLLLLLLL—Lf. area,:11t;. - and11111... ..' in'.'.L the1111: westLLL.'LLLLL runs1"LIL'..LL aJlongLL1L.I'IE1:._.111I11IJ_"the line1111LL of111' the11.1.; NyandoHL'LLL‘IL1L'LILLLLLLLLLpL11LI'LL.11LLLL11LLLL'L'LL1nLLJL-Lescarpment. Here the ground is extremelyL.'LLrLILL-LL'L' ruggedL'LILn LLL1L1and the'LILL LILLLLI'LLL‘IL.outcrops, while'I.'L1'|11L1."11_'.I1|1.."L'L111I.-'L1-L11110cal~lywdl exposed,LLLpLLLELL-d areL.I'L- L‘IiILLILoften scree-covered,ILLL’LL-LL'L'LLILLL1LLLLLL'LLL-IL1ILL.especia1l1y onL111 theL116 lower1L1'LL'LL' LLiLLIpLLLL-slopes. 111In the1121: p1proximityLLLLLL.1 LL LL'Lof theL':1L escarpment,LLLL'LLI'LLLL'LLLLLLL. both1L-LIL'LL .Il1.'1LL"1'-.'L';'a'bove andL'LI1L1 below.L'LLL1.L'II'-the scarp,LL-L'L'LL'L'L, thereL11LL'LL has1LLLLL11LL1been complexL11111_L.11L.LL1I'LLLLLII'Li-L1LLfaulting LLI”IL11LLrgL-and large- andELILI'J small-scaleLIL1LLJ1-LL'LLLI'I:irLLL'LLILLLILL-LLLLLI1L1LLLLI1L§LILLLLLLLLLIintrusion and, although the1.111: same.LLLLILIL rockI'LLLBL typesL'L'I;‘LLLL have11L‘L‘L'LL 'been1LL'LL1 recognized.LLILLLLLILLLL1 byLIL Binge11IILL1LL andLLI'IL1 by1.‘I'_L' the‘LILLILL writer,LLL'iLL'L'. considerableii151di'rli1-I11L.‘ discrepancyLz'iLLLL'L__LLL'-.11LL' in11‘. detafilLLLiJ ofLLII outcropLLLLLL:1L“I_I.L isEL'. JILL-:LrLILLapparent on1111 the1.111." maps,LLLLLLLLLL. LLLas isELIEILLL'LLLL-L1IL-inevitable in1:1 reconnaissanceLPEI-...LIII' .rIL. ILLI_Li.1‘I111‘1.Li.I.-.I.-L_ surveys..1'LIi.lIIIJIIIII'~L':TI:'I-I‘1:-L AlongL..L.1§’.11..the easternL LLLLLLLLL. partL'LLL'L of1.11i theL1'LLL common'L'LLLL'L=L-'L-'L.L.L1 boundaryL'L-LLILL:'L-.s'.-.."L.' Binge1L1:IL.L_L_LL has.L'L'LLLL mappedL1LIILLLL1 aL-L .-'.i.L:.LL‘LLL.LL'~L§-'L"Lsuccession - -I'-..i I-L -.. I 1 - ofL11 analcime.1.1I'-r_'1L1I-_1IIIIL1.II11LL:=LII111I':basanite flows,151.1111- LL. overlain'L'.L.'1.1.'Li-. “1.1. byI—--1'1 phonolitic1111—1LIILE.._'L..-I .-.-L..-I1-I-L. nephelinite,.L311111";q' 1.1-1....LL-L. followed_1;1'1L_.1,'L'L__L|J'I1' by''.I.'1I. welded'LL.L_LfL:!-:L'L"" ' andUL L.._ .' ...'.I L, . I_ -I I . -.- '1-' ' - trachytic..-.lL_LI-|_L L.1._ tuffs.IlLi1'LL. The11.1: 1.I.'II1.I.|1-I.1L'L.1I1erosion '..1Lof the1.1IIIIL. MteteiILII'11LL_I".'L_1 river1.111: hasIII-.'I.111 L.'.KIJH‘LILLJexposed nephelinite[1L'1_I11I1_'._1.1|I1iI[L.. .1_'..1I_-'.L'_,1.[1T1I1I._1'!I.Li1_ILI1L"L-agglomerates ‘-. ...'...... '.I. L L- .L:L-. . . :; r .- flooring"L'1..I1'i.12L'_II_ the1'.-I||._1 valleyL-'..I'L_1'- and.LLI1L1 ten-1.I.':L_ milesll-IIIL.I"LIL eastLLLLLL; ofL"-_ the1.1.1.1 NandiII11-LIL1L'1-;__- Hills-SonghorI—;I_IiL'L ‘I-I. L. L‘:-_'_-LIi1L_-.__'-._-L road_-.~L-_:_.L-_ theI.I|E highly--l- '1-1 - .. . .. 1.1 .'- .. Hi...— '.L .. .-: 1 . L, L -L - II irregular-.-.;L~__.I.LL. LLLLLLLLLLLsurface over..-.-L whichLL11.L.1 theLLLL L11LL|L.1.-:analcime basaniteLLLLLLLLLLLL- lavasL-LLL;-..L flowedL...LLL.'Il'-L..- rr1_-L.1. isLL 'LL'-.;L:_-well demonstrated.L331 1111' ..-.-I_ -I. . .- 1'. I - . .I- -II -- |. 1 -- -I.I-I. rIII 1', . .. L. - I Further1'1.-'L'LI]EIJIL eastREILLTL-E theLiII1L_I1 basaniteDLILT'LLILHLILL: flows,111.111.1111. composingL'LI1LIIIL-IL-1'III1'1LII11I'LE-1much.11”; of1'_I1'_ theI_:I|L_' upper”I‘ll-1:31 slopesj-L'_1_I'-|:II!-;_"'~LI-'11:|:Iof TinderetI;:I_ii‘_I1'I-II_I1"II: in|" the' L .I' I - I I_ . _. .I' I. _ | . 'I- Kericho1L~LLI LL'LLG areaL-LEL'L‘.L doL1L'L not13.11. extendL.'LLLL'IL'L- intoLIL-.1? the1.--LL presentPifihL—lIL area,L..:L‘.1. norL‘ILLL wereLLLLLL theI.11LL‘.phonolitic' 'L...I'LLL 11LIL‘LL3F1L11L3111111L‘nephelinite:I I lavasi'.‘.'L 1.1L. whichL.'-.11'I'L‘11 overlieLL'L'LLL'1ILL the111C basanites:L'LLLLL-LLIi'LLL recognized:'LL'LL;:'L1.L'-:L1 northL1L.L!'111 of the111LLL equator.LLLLLLLLLL'. ...IIIIn 111;:the 11LLLLL'11'Lheavily wooded1L1.IL'|.I1.1|._11.1 LLLLLLZ1'L-LLLLL'.south-east -'L'LL;'L1LL1'corner ofl.I1'II theL.ILLL; .LL‘L'LL-Larea LLL1on L111:the .L'LLL.southernL1111LL L1 2L11111‘LLslope L.'-.1of Li".the MteteiI'LL-L1L .L_ valley'-.':.111-.Lj.' unrelievedLL:1.'LL1ILL' 'LLL1 pyroclasticLLLLL'IL'.'L'LLLLILL rocksrL'IL1LLL apparentlyLET'LII1'11" L.' outcrop1:.-LL: LCF'L-IJ toILL. aLL heighthigh-L of.L:_‘ 8,80011155111,. feet.{:L.-LL NorthIIIIII"1-111II1:1III.|.I"LIIof theLI'1L equator1.11.11.11L1L1II theseLiLL-LLLL haveLLLLL beenELLLIL includedL:1L. -.II.'I.1L-'L1 iniz': their-‘.'.'1L-iL' entiretyL-.1L. i.".:.._L withLL:L.'.-1 agglomerates:1 of melanepheliniteLLLLLELLILL}111L11112.L 11111.31and 111111L1LLIE1IL'phonolitic L1LLL'11LLL1111z'Lnephelinite 'ILL'1T1I![I1|.I_I11III11.11I.I1III1_composition. I1I|TLThe lower1L.1L.L..-.LL‘ partL'LELL'L L.'Ifof 11112this L.successionIL'LLLLLLL'LILLH can 11-:be LLLLL'L1LLLLLL1correlated LLiL11with Binge's13112§LIF lower1L'1L'L'LL'Lr TLEQ1L1IWC11111Cagglomeratic :LIL'L.tuff, 1.11Lthe upperUpper partI1'.-'.L'1 LLL'f-L'LLwith hish1L' upperupper weldedLLL1L1LLL1 and31111 trachyticLLLLLLI'LLL'LIL tuffs.11.111111. *1' References'ILLL-.L.L..LL:LI'LL-..--L are-—. givenL.LLL1--L onL.I:1 p. 43.—1..I." _.__-_.. _._— . 4.1 III-PHYSIOGRAPHYIll—PH 15196 E11151. PEI-[‘1' [1}(1) “11111111211111.1111TOPOGRAPHY 11.1111AND 1—111-113-1131:DRAINAGE TheH1: 1111-3area -:.'1111can 1.;-be 111111d1211divided 111111into {11-11:five 1211111111111distinct 11111111111111.3111physiographical1111112111 regions11111111111 11111111111c1composed 1?.of three121111113 major11111111: units1111111; and111111 two111.11 less521111 2111111111”:extensive 111_1'..1-1;1'Isub-units111 (Fig._ Fig 1:}1):- "' c ~ m . I .I - I __. I -._ HI I. "‘I- _rI. __- . PI' "III II -.H' _ _ ' - - - -_ .IIf - - -'-_---.-' ' ‘- -I-.,\_ -"-I-I.______' I I _._ I I -— u I '1. _ _ - _ 3H. "I. . 11. Ila- _ ..I_ -—. _ _ _ _ _'-I..__ I. I ' ' _ I {V I "' -. I ' r"' HI' " .- J".II . -_ _ _LH _ _ . .I _ -- -- _. - __ -- _ 'II. I“ _ .-" ' '1. 3"- rI._ __ — u.- - "-I_ -I. ' -I. .“ .. .— 3. 1I|_ - - _ _ _ _ - f ' _h I I - - — - _ - _I-l 'h' u "' ' ..- _ _ - ._ 11"” I .I -.I | . “'I- __ .- _ 1 ._ '1 _L F '\- -I. - _-.~- — I I. I. '1. - ._I I * dl --'-._ --I_- - 1'“. I. _ _ _ I TI 1- I: I I K: I'd.- i'J'I' h I _ "I- I _- -I. I . II. 'II. E.- - -I_ HI. _ _ I .- I I. _. "III—.._ .‘h _I: F'- 1;. .I.-i: ID _ It?!“ .. _ .- ' -- -I. "' ' '1- - - I _ . .- " "' .1 .- 1 - 'II. .- - - .I — . -. . 'II. ---.- 'I _ -- -. 'II. I. "'- : “'1' —"' --' _h I NR .- .I I I _- . I-_.- II. x I “- I- '. I. x - _ _I m _ __.- I. - .- " _ -I. _" -I. '1- - -'" "'I .I- __'I 1-H I P 'II. F,- I I.--' 5 -I.- ' I 3""— I"- I I- I. C I.-II II _ .- I1I_- - _ _la '1._. .- I. _ - I .._ I. I _ l— l“ _H I . - - --\-__J .I- -'- .1"; __ -' A". -' ._ '. _ -I. .-" I. : I. I. -' "' '— . .— .- - "' " "I I. _.- — " “-I. II-{II F If I I. ___ ' m “-I. - I -' .-' ___- 'I.._.d—_- ' m a _ _ _. I.I I. ___ ah-______I W- I. I _ _ - 'I II. ._"‘-_I- -- . . I .-- I. I. -II. "1- ..- —'~-I. __I- " __ ' .-' . " I ‘1 ,. - I I . _ . -- —-I. “I 'I. " _ I. '- ‘1 I. _ '1 'II. .- .I- I. a . . - . V - 1I-_- 1I._ .-- - . _ - .- 5 T . I . I"I "'- ___ . _.- ‘1.1I._—I._.-' .- .-__."' __ .- ' .5 " ' II. I” F H“- l' "' ' ‘1 '1- - HI I-I.______- _- . l. .. _ _ 1. ,fi _ a I. I _. . . I __ . I I III. I I . I - P _.__ ' . . - . - 'II- - I— ___-— _ I . It: -_ . .--"l | -_.I' f__ H '\-I. H H. -I. I .I'" .I' -E I... I. I _L __ I—I. -c ' _ "-_ _ _ ' _ - ._ _ -- -I I II. - '- I .-' II ___ .5 I. I.- .. .'I. . . _ -I. ."H-I—"J. . I In II J ._ _,.-' .-- _ 'I—. 'I . J _ _: I‘MI .I' __F- I‘{.-" I I, - .._- -_L -._ - I. _ '1- I". 1-1 "1 .—“~-'I_ 1’ If ””11" r" _. . I '1: -. . I I__ - I_ 1"- :II—I '1__.-""' . . '. x '- .—--—”' .I _ .- .. __I I'. . . I I “II —. - . .- . . .- - . . .1 "f I 'I' ' - r" __..— -. - I“ 1’ 'I — ' ' .,.-_--_-' 1 “I I "' - I IIr I HI. 'I ”a" '. _.II- .' 'l “‘15.; I. I'll-__- - I“ F -. ‘- - ' - '1- II‘I- I hm ._ -I...-" 35"" I”. “I .I" - i rid-__I- 1 __P - __h-. __\I_ _ I... I a _ - I I: .I." .-" H Ira-Ff- If ' :1 ._.' _ _fi ' -' .l 'II—I.-I._.-I-I—I_ '. "' _ -— 1- I ' _H’PII ' ' I II I- .- C ' 1' -- L' - '-. a ‘ a ' -' .-". _H.’-' I-T' . -'' “I _III,' - _ x__. - 1-5” - -_ "”""""‘* — I I. .-I- ._ .-—I_____._.__-' I '1" r II .I.; .- 5..Ii._ Scale.|J'H_ 0, ,,""'" 51?.. I.“10._. .MilESI.-:"...__:.- I.-' -I T :I u r L. I. _I :I. -I.I I. II. II'IH'I: I I II. .I-II .H- .I.. I'll I._|.. I'— -.l' Fig.F- 11.1. I-DrainageI——E}r:-IEI1:1=.-;1' and11111! physiographic1:11:15111111I 11.11?-1* unitsI= IIi-‘_1.' of111' the1'“ Kapsabd-Plateau’3: area (1) The undulating hills of the Nandi Special Area, to the west. (2) The Uasin Gishu plateau in the north-east. - 11:(3)- ' _The1111-:. Tanning:foothills- ._.'.:'. _..;1[']I.:and_-E 1111-3111twooded-. :.,.-' ‘1'."1I":‘._1I-.1111.1~Ihighlands1'_._... .. 1‘1of:' .-.:.!..the northern-i'..I..I-.‘.‘!:I..I'I_..._ flank."-.._'.|.-..I|"-. 11.of' .‘_the.1153 ___._Tinderet1113-11.11;_-.. ...volcanic.11..I11111.-1.I_ j. mass111.111 to11.11.11:the1:. south-east,1111111111111,. ' 1 ' . .'Ir with1211111111:the minor111.‘l-."‘I[ U:"1;...---—units: - (4)1—.' TheT= .1 Kingwal:I,.1:-1I-... swamp111.111.1111 in111 theIIIIE centre131.1111 of1. the11:1. area.Inert 11' T1”. }I'n1-.1.- .1:... "1;”: “I. -«III.-'.-- -I;-I-II-II--I.-..II .1 I“. -'I--. .-..I1..... 1... -. .;.--- (5)1.} The_ :.-'I. highly1'L‘L' '1- dissected1.1.3311; IIJ. Nyando: f'lJ-JL'L-IMII RIIMLALE.'.Ei..H--:Lescarpment alongMIL-31.5 theI..I.L southernH1]I—lLi..'-I_:!II boundary..llI-:L-'.i-|.'L:|'_1.a ...__The11.3 first11111.1....-.'-unit111111. isI11 111111113111qcomposed 1.11of low11.111.. rolling11.111.11.11-.1'51-111.11hills of1.1:-: more1111111“.. . 1.1:or-.'--less11:a granitizedg1:11.1-.EI:111.'.'..~ g11.1.IIuIgneisses-_..' .. of-11 the13111: Basement11111111112111 System.fig-"11111111. In1'1 the111: main1111111 theseaore11.21: .111: flat-topped11:1141111111111 ridges11111113 with111111 uniform111111111111 summit31111111111 heights1.511 E1111; 111-111and 11113111".-111111:1115;.'are apparently I'rIL‘the 1111111111311:dissected 1:. remainsr 3111311111 11111of a mature11111.1: plainland,:111111l111111. 11111111:above whichIll-1"! 11:11:rise occasional11151111111111“ remnants11111111111111 111‘of a11 previous12111311111111 peneplain1.111111131315111 bevel.h-31-131. The1'111: drainage1111111111541: in111 the1111' Nandi3111111 5ELL-1'1 _i -. ..._ _'. . '\.---"I"\. Special51111::L'.L=L.I Area.-‘IL"L"LL is;~'L of arborescent:-..":.1'-'.'L'=-.L'-L"-1I pattern.11.;11'.L'-;';1. The middle.:LiL!‘IL' reachesL'L-LLL':1LI ofL: the-aE'-- rivers.""L_. "' are|._.'|_I matureI.III_1.'.L-EL_ .i'i '1. LT and.'ILL1LZ'IL typicallyl}-"£JECELEE}’ cloggedL'iL'11'1LLELiL with L'.I-L'L'L:extensiveI‘LIL' ILL' reed-beds,LELLi- EILLIE'L. but11111 theLLILL; mainJ'HELEJ'E Mokong-Kimonde.‘IELIELL'IL'Lct-EILiILLLILILJL: river - " 1 1 ' _“.—.... '1_'_'.'I"i J .1'..'1 Tr'L-;LI'I-_ 'r'-I. .'i-.11? system displays more youthfulE-I‘ILLLI 1 Lil characteristics-L'i‘:'L:.'LIL' 1L'1'I I31 11:: everywhereLIL-111111.13... L. downstreamL1.._._1L I.'-'I—I-'-\-—‘:- L.IIJof theI.-:1!—-'I- BaratonB:L.II.E...'-.'.E Veterinary Station. The second physiographic unit, the Uasin Gishu phonolite plateau, is an extensive lava.-L-.LI plain1.:-i11:1I. risingr1511; I'.‘LL:'.1Li:ifL'steadily to the.1‘.L: -L"1-.‘_Least, the.‘.:1L' 1‘.‘.-..I'..."-'-1'.'.monotony beingEILEEN E‘ri'iLLIi‘broken L"‘.-‘:'only whereL.'.L": the“.31.: upperI—‘IELE'J! of the1i]: two21'1L1 major1111-3111' flows that'..‘i:=L areLIL-L.' present1‘1? .L::'IL forms.L1‘..I~. a'L distinct'Li“ I‘.. scarp..LiL-LI'L‘I featureLL'..I-1L' rising..L.'.I.;-_I above.L1IL-.L- theLELL'. lower.LI'LILLI AilongL-ILELTIILLL the'L':I-'L- eastern1:44-2:11: !boundary,Ef-L.IL:11LE'L-11"L'. north11-.‘11'LE'1 LILof Kipkabus,EILEf‘ELi-iif'li. L'L'L-z'LILLerosion hasE'.'LL~ produced1"."L':.L'_L'.-L'L'IJ ’:a "‘IL-Lr'more undulating...IL.L.!LLL LIL? -1.*i-L_L'surface —"1on the'I" phonoliteMIL-“1.11 .IL' ELLLLLILlavas lying'I-L'I nearerIIL'LIL.‘ 1E1:the shoulderL.:L".1L.'!-E L-Iof 11L.-the R131Rift Valley.'1. "111]"-. T111:The .E‘I=L'.'~rivers 1running11.11.:111 HILL”—over theLi1" plateau11E-:LL=:II'L formIII-'1‘ LLa sub-parallelLL1E3—1111I‘LLEEL'L consequentLL'.ILLI-L'L1'.L'.I':1. drainage.' L1111'EILg-L' system«105111 incisedI1LI-LL]. 1:"on 1:1:the lava:ZLL.1 .~'1:‘.'surface, theirE'.L-' -L'L1_-L'~Lcourse, slightly- L:.1Ii' north.'.11'I'LEL ofL west, indicatingIL'ELL-LL:1'L__1 the‘.itL' LIL-I'L'LJgeneral LL11:dip of the"‘L' flows"L"L~ ‘EEE;(Fig. 1). TheIII: TinderetI.'.- 'IL"'L'.I highlandi11I:=_i"I.L:IL1 area'L is parti‘ILLIE L"of LLa -.dissectedILL-L'L-L'L'. volcanicL LL1:I.L pile11- L' L"of lavas LI...alternating:1:.i..":': '-.-.:'..I:.with Ln'1L1z12L'1'LLLL'I'Lagglomerates L111-Liand tuffs,:1‘.1~.. 1i“:the .':=-.'-.'.':'Lrivers forming11.11'1'1'111‘11 IE‘LEthe I'1L1:'LE‘L—'-L'1'I:.-.'Lnorth-west -L..LLLJLLLIL‘Lquadrant 'L'I-of LI.a radial L -IILLLLL' [JLLZLLLIL 1_Fi1. 1'. if“: ILLII L LIL I‘IL L'E‘I'L11'—I.1-L'L!IL ELL :1: --.1‘. =I.11'_L"LL' .LL"'I‘ :__'1'L'.*IL' LILLL. drainage pattern (Fig. 1). The slope of the river-beds. is _at1 an angle_ _ rather- greater than the dip of the volcanic rocks, so that progressively1717131; :'L'.~. ~15 LIE-I- 'ILEI_L]L.older rocks.IIL'I_""'.."'" -.E.!._are exposedL=:1L'Li 1.1...-to the north and west. There are two exceptions to the radial drainage-l:"__'L_ pattern-theL.L'L .L'LI'. major - - .. '... '-_.. .. '. . 1 rivers, the MteteiELL-L... andL-‘LLIILI Kipkurere,E‘ILL'EE‘ELL'LLZLILL in.[L theLIL. ILLIL'LLextreme'L'fl-‘ south.I~ I'.JL11 Both11L_':E' have' "‘. deeply' incised 'I'I —- - I valleys and flow south of west. Their courses~. 1-.-;.:L_I.follow faults'.a I.‘.-parallel'...E-Lr. toLI the main NyandoL_'-.L'-LII.LiL'1 faultiL-‘LLIiL directionLiLL'L'IL'LIL11L :‘.'-ror zonesL 1'11of weaknessLIN-I where-.-.I'_IL_|L the[11- faultL'Ll itself.HILII has become indistinct,1'1L:::~‘L'L.‘.1L'LL branchingEEII'LE'lI'l-LIEEEIEE and'L"l[EI'L1 swingingIII'"-:-.'T‘C_'_'_‘Ii;-__' north-east.E'EILFIEEIE-IL‘TL‘I'. L-I'.—. -.—'1.- J '.- TheLh-L': Kingwal1-L.I'-ILI.LLL andL:.I:L1 Kiptergesi-L:1:ILL':' ”I'LL-E riversE'i"L-L'L'I‘Ii andLEE'EL; theirEL'EIL'EEE tributaries1.1L-'L.LLL.ii._"' drainL'LJ I.'..ll. a large section of -' ' I 11 ‘... I'I'I. -- I - -'I.:' .'1."‘ I-‘II l-— r'I'L'r '- .'I- ‘I- '- theLEE'h: north-western-‘l|-_llJ-.1}-E._'-'I'L-:"L\. J] flank[.1.-1l of1.5.. Tinderet.TJ|_LE'I._.II.IL.-'_1 In‘EL! theLIL-2L- centreLLE'EEIILL ofI'L'I; theI.'-EC area'Lli'Li theseEL'l'L‘E-L riversFEEL-.2217; produce1__".I.__.‘-'LiLL-L'L' ..1L L... '.:. .'.-. ...: substantial.L.LL_=.~...L1'1..L-Ll I.I.LI-LIwaterfalls,-.L1..~L. droppingLILL_.1I.L-:I‘I_..- from the top of the-L lower=...""'L_'- phonolite"1”.- to the level of the extensive'..”ILEL‘E'IrE'I‘LIL.‘ swampFE"- 'L‘L:'i':;'.'}| which'IL'IE‘IELTI footsEI'LEIIL'IlfII the[.'EL". scarp.TIC-CL'LFP- TheEE'iLl KingwaliILIIIILLLLE swamp has an area of some FEE1- __'..':"r' sixty-.:'L.I-. square~LLLIL-LI-L'. miles,.11.!L'IL. andL-1..L' liesLILIL atLIL a.. heightLI-._'I;LI,L._ ofI.: just11.; over;__'LI,r;[' 6,400F'I_-3—E_il:_:' feet.1:L1_ This swamp region is considered to be the site of a hollow in the undulating'|_L_E!Lil-L'LE.:1£ IIIEH'L-pre-TertiaryE L: L'_'L: surface,~I_.'i1L-;IL'L.. andL:..ILi is probably floored in places by waterlain tuffs or agglomerates from Tinderet. The nearest--.ILLLL_L,I~I'[E‘E_15~IL.IIL:.:-..I1.-I--. Basement- -.-.---.. -. -|_I SystemE")».-.L[..'. |I_--_ -.:-. rocks1_L_IL_-.L_~L—_- .L-'- - outcroppingL.'L-LL'LL_.}‘I:..II!.__-.- . -_-.. L-II — 1. atJ.-_l_ swamp level are seen north of Cheptet. Drainage:_’.LlIIJLlEL- nowEL'LI'L‘I beingE.-'I._|E.!" prevented:1" to the north and east by phonolite, and to the south by agglomerates of Tinderet, the rivers escape to the west over a series of rapids composed of hard bandsL11-111L111 inEL: theL.II' BasementLLL-ILILL-L'n'. System~'13-.LL'11'I gneisses._g1'L1L':.=:I'.:'L The'l 1:: fifthfifth physiographic"IE'II'ILLLI1—1pEE1L'ILLI'LiILunit is11L formedIL:I'-.'1'LL'Li by1111' theLi'I-L'= Nyando."jL'LLLIL'LiLI LrILLt'LLL'pLIL'LcrLi'...escarpment, running' sub- 1-Lll-L -.—_|.-‘L-.- .-' L11—[._. .1.—"..- parallel1 to1L the1.I:. equator- .--*L.I alongLL-I 1'.-.: theLEI. southern-L.-L1I-- boundaryI_.-II.__-|_...|IIL_:.... '-. of'._'I the.|_-__ area.L.LI'h...|.l _ TheliLL characterII_ I.: of the L. | scarp varies'I. '..-'J_["LIL_‘~L with"LE-'[i'l the‘Li'IL‘ natureE'JijEiJi‘tf ofL‘.IL'l the'-'I.l..I'-_ rocksE‘CJL'EI'LTE ofIl_'|I_ which'-L'-.iLELji‘I it_11 is1a. -:.:_1."II1_1-:_1ILL'L1.composed. _1'11'The watershed dividing'LEEIRILEEIELIE1. " EE'I— ' thetil-L.'— riversTI'LL'I'IL-.--- ' ' descendingLELHLLI‘ILELHL-' " -"I :I 'I 1' the‘11::.. L. scarp-.L.L'L.-"11I‘. face’[LLLL--" "'- fromT111111E " '1 the1tLEILa Kimonde-MokongEIL..IIL‘IIILEL-EILEI...IL-LI.‘.IL:5_;-:+I1~ " I. -' ”'Ir' l"'I"' river system runs"I..-:II_L' on1yI111i11 some:ELTIJT‘EL‘ six~_'LI_.'=L orLII seven.I_LI'L'ILL-L' L". milesILILEL'IL north11LI."1E'.— ofL11; the1! topEND ofKl] the.EEEL: scarpE'EICuElr:I"IFiL_1.(Fig. 1) andLII'LL': hence11:11:13 the1 drainageL11':I.:L'I'-L1g_L' areaLLI'L'LL of1'11 the111:: scarpILLI'LL1"11 rivers.riLLIrL is1:1 smallmm“ andL11-ILL theLi'I-L' volumeL'.ILIiL ITIL of1_11 waterILIL"L1LL'I‘ carriedI'L"L-IL.' highly_ .Eu— 1__... variable.II:LLE11L L-LL'LLiand- LIL.L.L.1L:L11LLdependentnix-1. . 11- on'11 fluctuationsfi. L1LL.IL‘..L-1L~L.'i :1- -. in1.1'. rainfall..- :-.IJL-.L:.-- --'-:| {1.1-L11.Often,-- :-. 1. 1r.---.-however,LILIL-LL..Lr.--.. .1. the'IrL.I.-..1. volume.LI - :.1I' .II ofIL':'- water flowing111.111.1111: is large:.-:1'-LI.L' :11andIL: manyI11LIIT'I. of the1.1“;L rivers::"L-L'.':.. descendL1IL-ILL.L" ILE impressive:L'E'E[.'!‘L'L"~~I rapids.:‘L-L'..‘-:LI.-.. Hills3 in alongLI' 1_-' the'.‘I:-L- shoulder.ILEILILIlLiL-I' of1.1L theLLIL'. scarp.IIL'LLL'p. approach11111‘1111-LL ELL a1': heighti'IL-1_1.='IL ofLIL 7,000_1__IIII_'1 feet11-31:: whileIL.I'}I.i|_L" 1L1to the'Ii':L:.~LL1Lll.=11_hLIsouth the piLtETEplain lies”Lg-L :11at EILEELIILIL'below _1_—111114,400 feet.1'L'ILL. (2) EROSION BEVELS (a) The "High Peneplain" (End-Cretaceous?)'i .':..I'EL'L'I'-( .E'EE'EL'I'L"L':-T.I‘LI'I'L'1 . I NorthTILL-311111. of-L~:' I_|'L-L:the NyandoI‘IJ1L'LL11LL'L1 L.L-LLIILIescarpment1.L.1'1: iIiiIsLhills L11“of 51337111212.granite, NyanzianENIL'LlI'lfliElT'E ‘LLEELS'LLLZ'LIJvolcanic rocksI'1_‘.IL"r-'L."I EJ.and11 L.' BasementJELLr-LL'LLLIIIL'L System53.111a gneissesgnui:L.LLIL':~L havehLLLL: .‘.I'ILE'ITJ'I'HE'Lsummit heights'rIL'igh-fs approaching'.IplfLILLL'EIinLL 7,000T.L'_i|._}L_i feet.ELLE. JustILIL’I" outsideI 'I' 111a."'_.'IIL'I. the‘II'1L' area[111111 to1L'11Li'Ithe west,‘I’I'EHE.. L-ILlL‘IILIELLralong theLhfl NandiHELLILiL faultELLLIIL aL1 ridge of1'11" hillsELEI i~1 hashLILIL summitsILLLI'III'IIiLrL again41411111 11111.1:‘L11112hiL‘Igapproaching 7,000TLE'LILJ {15111.feet. These,TELL-ILL. LLILILILttogether 'LIL'iLE':with .I’ILIELLEJLLIL'L:Aigabbyet 111111and the1hr: hillshiElI. toLL'.I the1h: north-ILLII'LE'I- ILLLILLwest ofL1f HLLILgLLiL-L'ISangalo L-IL'L'.are 1'-.~'LiL'1'LLLIE.~L'residuals 13fof L'LIIILan LLLI‘EL'early bevel:I‘ILIL'LI LLI'ILEand are included1111': .'ULEC‘LLE bybf ShackletonShLLL'kEILLL LL‘.II‘L' I ..._.1 I'liLITEi.(1951, p. 3?"?379 Eil‘LICEand IILLLp}map) 'L'Lr11_1.111L.Iamong [1211111311.eremnants L11.of aLi "hzgh"high FILIL‘ILIDE'Lm“peneplain" possiblyr1L1.ILILi HI: of .FuraJurassicfi E‘LLL —I.L ageL'LILI1. butb111, which1LILi'IiLi'L may111L111 beEIL' 111.11"of end-CretaceousLL.Li—E'L.:L'1'LII-L'I:L1I.1~L age.LigL'. . 6(I 1:. K ' ' . .I _ _ . - ?_ r 'F' . _, If . ': I :- a .- —Idl . .-' .-' ." F 'h-_- if _. - I:_" _1- .- .' H.”- I. ..,_ ' .II ._ _- 1C“!- J'- I. -' .5e ' - "'. L' I' - Kim-raven- .- I Illf I. “'1"! P": --' ‘ II--' . ""-.-' "I ~ all '5' . “I .I' . _I-' " .L '5... . "I . " . . . r, , I}. --.«. ._ _. I. 5 I '.-" - " -. . '\- m __' II . .r . I ' __ I_r . x f . , .. .-" J I. - “a. .-" n' " eff-I. d- -. . . I _1‘ ”ii ' __.- _ " gt .a" " . I. III. “Swim.- ‘ '- ' ._--- - F II": . -I _h - I -_ = . LJ'WJ 3-1. a.” '3 a. 3 F _ . - . . .-.'--“ ' .!__ r . .L-ifi"- I '-.'-.'. - r' kT-J-"J ._';"'-."'£' .uL-IJL' I: ' _,.-' '-."'i': !"'!':E_ Tin-LII”: .I-T.” -! I I. 'I, .- "'I. I - 3-“ . _ L"-=-I""'I'. yeah. I --*r+ - fir?“ _ VHF: _ .-. I. . ._ 0.20' N. _ _ ""\-.._\__H_\_ ! ' ..,. II-\._ : .- .- _r_ -... - :I L' IL, .- III. I “a III-I —- _- . 'H. " . .-,:;-- " . H.“ I I : 'f"-.T'"-:‘ '-"':'_|:_"'""'.' .."_'- 7'3 J , " .- .-' .-|"' F—fl41__-IIIE" _ . I _ . .I‘ <-,---/ '--, “f Li: . '_-'_"'_r I-“' '. " :1“. 3.:'-r:‘-~;:I ". “'- - --- '-_-.---'-‘ ' r'I'fi “- I'FII- _.I" '.' . ) -- ' ,'r - I . _-'§_; I. I... I. r,. --. I I- .. ' II a. "" . II . 'I.'. .\'\c-,-J I __.-"' - _ . _. ~r . I_ _I “I " - T .. :3.- pct r .-. :. L' ,. . (3" ' .. ,- __ _ _ :' gong '. - . I. I ' _. II.- 3'. -".- ' Ii ‘3I‘11'H-"i" 1-1-5 _ E _ .- I I .-" . __ r .-' -- ' I I I - - 'III ".--' I .--" W's r. r-“ =.-.'.s -. 'IE- Earntnn fr“. I. . HI.“ I.- i .e" b". . l "‘fika .. rug-Ina! ! f '13. .. .. | .-' 5.3.4.419 I -~H'. 1‘ .=- -" . _- I.-I . -.-" \;__'-_.,.-a' -I. 'H. -I. 0.10' N. .- n' I‘. ."I ~- " -- HIM".___ I. -.. __.-..I 1.2 . 1 . ' {-II III-I-I-I..-I. '.- .- _a." -' -—-;‘r-I--IJ _."'—"' . . ' 1 -. L--._ - _ .-' _-'' .'.L -. .. .l .I' - .‘I '. _ " "I. ._.., __. -I- - . "'I' -' - _I____-. [I—I. _ . " .- ' “HE-In I:. l-I.I' fi b KaYO : 6763' .- -..r._~. "afi‘ .xrwfl f“ . .-= . PM: flfl . _' . .‘ _.I .- .-"' _ .-' :2- ? 4%,“. ' " . "" . .' ' “If .' -' .-" J: éi _.-"" Jig-'7‘: .-' If; 1 If: ..= .—' . - ' -. I-I'I” -_ ' ' ~lfi . . .- _-___Li._._p EquatorEnuatcr Enuaffir Fig. :—2-SketchHhetch mapIIIIIp IIE'of thefin:- relationshiprelntizmwhip III'of Ii'rI'IIIi-[Illerosion bevels,hlL'Tifi'I'. Miocene_‘IIEIIEEIII- Lurl'IIIIL-IIIHsediments and '1'I311iI‘IrgrTertiary volcanicIIIIEIIniI: rocksI'IICLLH inin the Kapsabet-PlateanHaipmhut-E-"'.'.11I'.'.'III are“area T7 (b){III} TheThe: Uasin{1'1-111:1 Gishu[11‘ 1.1111111 Surface13111111311111.1111 TheTIIc plainland,[1I11111I11111d1 theIhc :.Ii1.'11cc:idissected remainsrc1111111111. 111'of which form1111111 .11a conspicuousc111111pi111111111. bevel11111111 in111 theIIic area1111111 11r11111111around KapsabetK11p111bc1'. 111at a11. height 111'of approximately1111111'1'111111111-Ic1111 1111:11116,600 feet,i'c. isi.1. c1'111cc111c1'Jconcealed byI11"_.-' 'TcrI1111'11'Tertiary 1-11Ic11111.volcanic11 r11cI-1'111rocks I11to I'I1cthe 111-1111east 111111and north—1111.111.north-east. Inspection1111.;1cct'11111 1:11'of II111the heighthcighI 1:11'of IIIcthe b11111:base 111'of 1111.1the plateaupIatcaL: phonolites[:1II111'111I1Ic11 shows11h11'111-11 thatIhaI theIIIc surface11L1ri‘11IL'c overLII-'L‘I.‘ which11”I11I'-'11 theI11: lavasIII-111.111 flowedI‘I:.111.-'c11.I slopes1.111c gentlygcnIII northward111111111111'11:'1I from1'1'11111 overcII'cr 6,6001'1-{1111'} feet1c {IIat Kosirai11111111r1111 to111 6,600{1.1.1111 feetl'c 111at ChemuswaI.'.'.'Iic111111:111-'11 and1111111 to111 6,400{11-11111 feet1'c west111c111'. ofIII Eldoret.EIcIcrcI. LocalLcc1II irregularities'rrcII111'1Iic11 occur1'.Icc1_1r and111111 11-11Ic1'I111':waterlain tuffs,11111.11. mudstones,:1111d111'111c111111111and grccngreen cggI11i'11cr11‘1c11agglomerates ricI1rich 111.in 11:11:11.1“.fossil III-”1:111:11wood 11:11".are 1111111111111]preserved :11in 1111111111111”.hollows 111.in IIIcthe 1"":111111'1peneplain 111111.11111'c.surface, 1.1-111111:while locallyI11I-"1IIII.-' II1cthe 11111111.".flows 1.111of IIIII'11111111Icphonolite 11.11.1rcwere I'II1.'cI':c1.1diverted 113:”by upstanding111111111111i1r'11; residuals.1'1-11::II-I'11I11. Algabbyet,iIEIIIIIJI'cI. EIEIIILIIE‘IQstanding 11111111111some 11111}600 feet['c 1111-11cabove theIhc 11L11'1'11‘I'111'II'111‘1-‘Igsurrounding IDIE'I‘J'Iplain is111 presumedpi'c11L11111-3I1-1 I111to 1I'"..'-I'.-I1".have been1c1 1111c'11such :1a 11111311111111residual, 1111'111g11though IIIcthere'1: is11. 1111no present1111111111111 .11-1111111111111evidence 111111that 11it 11.11111was 1111'1'1111:IcIc-'1"'1surrounded by1."-1. lavas.1111111111 11111."The 1:1Icr1‘II1'11cs-1interfluves formingII.”1:"I1"IIII.1"1 11111111251ridges IIIto ”'.IIcthe 111:1IIIIIsouth 1.I1II'.Iand 1.1'”1."..11Iwest 1'.".II'.‘of Algabbyet.III.I1111':".‘1111':_': :1."-'are 11611111111111'91I1I11demonstrably higherI1111I1c2'1i1'1111than theIII." base1111111”." 111'of II1:.:Ithe lavasI:1':1 1.11 at II"1i.-'.this latitude.I:1'.iIIII'1'Ic. ItII is1.11 likely1111c11-1 thatIIIIII phonolite1111111111111‘1.111 III-1111.11.flows '[TIIIIESEC‘IEI‘1ITICJI'1Ipassed almost toI11 theIFII." 111-”c111c1'11western IIIIILIIIIIIII'yboundary 1.:II1of ‘.I"1I.1_"the 1111'c1area, 11111111111flowing .IIIIIII'IIInorth III.of Algabbyet."I1g11L1I1IcI1 towards111111111. 11. theInc .SI-IrIII'IISorora hillsIIIII11 and:11'111 south1111111II acrossIICI'-'.”I1.11III'c1111-11.::11”11..I.-'1”1c:-'I_I:".1IcI”.Ithe area now occupied by1111' theI111} KingwalK‘i‘IgIIa'IiI swamp.111-1111111111 ItII is1.11 clearcIcIII' thatIIIIII theIIII': c.1111cr111111-I:extensive interfluvesIT'IIIJJ'FILII'IJI'II 111111-1111south and111111 west'.I'c1-II of111‘ Algabbyet,13131111111111 '1-”E11 13.11.1115.lying at1.111 6,60051.11110 feet1‘1-11:1: were11.11111: neverIIcI-cr eroded1111111111111 down'.‘-ILI‘II'I'II toIII the[III-11 level11-1111 1.11of the1111.1.31111111Uasin GishuI'.-1111I'.'..L plateau11.111.11.11 surface,1.11.11.11.11; :-1111;Iand .1111111I11should 111.11.not thereforeLhcrcicrc I11:be 1111.11'11111111111'correlated 11-'EII1with c1'111'11111r11111ccomparable 1111111111111summit 1111131111.heights in 11111111111111.11I1clthe Kapsabet area;1.1111111: r11111crrather these11111111: ridges1111111121”. 11111111111should bebc c1'.1:1.1111'Jc:'c.-.'I.considered, 11-11111with Algabbyet15111111111111.1111 1:1"and 1]1cthe hillsI'1II1I1'111 11:11'111—1111-11north-west -1..-ofI' "11111.11Sangalo.1 11.1.I'c11:111111111111111:1I11cas residuals upon the Uasin1111:1111". {_1i1'111:11.111111111111111.Gishu surface (Fig. _1'I2)."1 The'I‘IIc lava1."-11:11 17.111.11.111.flows, crIIIIIII-III‘III.emanating fromII'I'IIII III:the 1..”II11III1'_Ic1:.':shoulder IIIof III::':the RiftIII-1111 Valley"1"".1‘11111.” cIIIcIIIIIextend I1.-'-as far[111' 11:11:11:north as11.1. Hoey'sH11: 1-' '1: Bridge.11111111111111"The nature[:1 1111111".of the 1.111111ccsurface 11.111on 11.1I1icI11I1c11'|'.c11.-111I111.11which they lie has been investigated11.1.11I.;-. .1." inIII 1.11.11Idetail north11111'1‘11 11fFI1II111Iof Eldaret 1511:1111(SaiIlders,11111.. 1964)1131141 where"11111111111111 itII is11.1 1:Ic::'.'clear thatI:1.'II. theI111: 1.1.11I1'.extension1111111111 of111‘ Ii“:cthe Uasin[.5111111". GishuI{1111'1II1I .11I111”I::1:1:surface toI11 theII1c1I'1111rIIInorth isi1. 11111111111111;1'.-1111coincident with I-."Icthe KitaleIII-IIII-1" pIIIiIIplain (Dixey,[I‘IIIII'SI-Z 1946,II.I~‘:I1. p. 2411'.244; EIIIICI-Iictcn.Shackleton, 1951,111511 p.1:11 37")”.379; IILIII‘1'111.Pulfrey, 1960,111'13'111. 1.1.p. T1.7). ThcThe I:-11-':-'1lava base1111.111: 111at Hoey'sHIKE-1‘11; BrIdgeBI'IIJc-c liesI131 1.11at 11.2111]6,200 feet1‘1-1c". 1'1:and1'. 1111-1111.rises I111to I1.—11.11}6,400 feetIc 11-'c:1:west :11'Of EIcEcIrcI.Eldoret. T1111This 111111111slope is[1. 11111111111111c11maintained ini1: the=1I1c 111111111111present 1-11'c11.area, 111111111south :.1I‘of Eldoret,i-'.111111'cl. where111.111.1r11 the:1111: 1111111lava base-levelI11111c-Ic11c] reaches."cacI'1c1'. 11.1111116,600 '1'cfeet 111at {_Ihc111111111-111.Chemuswa. ‘I‘hcrc.There is11'11I:_”Ino 11.11111151111r11-:1L”Iwidespread 11111_:-"'”::III-11.'IIagreement 11.11on theLIIc HIIIII1I11.status 1.11'of theII".:1' Kitale1111:1Ic plain11121111 11'11IIwith 1121111111111relation to111 1111-1.the 11.I1II_1—Z'1-"ii1.1ccr1csub-Miocene bevel.111.1111. In111 11.111111111111121;discussing theIII-c peneplains11311111111111. 11:"of western1'-.”c.1111.1”1I Kenya114.1":1'1'1'1 Dixey13111111,: 1311111111called theIIIc bevel1.11111c1 now11111.1.- referred1'cI‘cI'rcr-I 11.1111cto the sub-Miocene,111111—11'1111cc11c. theII'Ic "Uganda'"1.51.11.1111'I'1' or:1." "main"“11111111" 1111111111:-peneplain.'11:: 1131111111111Dealing 1111111with 1111.1the 11131111111111peneplains111.11 11:.11'L1IInorth 111of I111:the 11-1-11'1111'11'111111Kavirondo {_1'L1I1I‘Gulf :'i:"Irift 1111:1111.(Dixey, 1946,III-11:1. I1.p. .'1-II244) he111 ‘.Ic11c1'111c11described theIIIc dissected1|:111.1-.11:11:.1'.I upland1111I1111111 11.111111111111113.surrounding theIhc Kisumu1.1-”111111111111 scarp11c-1'1I'11 11.11as residual'.'c11i1111111I. on1.111 theII111 "11111111""main" peneplain11c11c1111111r1 11.111111and c111'rcI:11:1hIccorreia table '.111IIIwith 1111-".the 6,500-foot111.51111— I11111'. plateaup1:1”c111: {111111(that 11:]of 11111the UasinI.':1-".i11 GISIIIIIGishu) 111111111and 1111.".the 121111111-Elgan- Kitale111i1111c plain.1.1111i11. 1111111111rDixey r-1-re-stated-11I1.I '.'-.1 .111.his 1111.1111c1111r1distinction betweenIIcI11. 11111 theIII-1". latter'1'111111" 11111111and theI111." sub-Miocene1.1.1'11-.‘1-'111'Ic1".:1c bevel111-111-1111 in111 hisI111:reportr'1-111111'I on1111 theI‘1Ic geologyQCUIIZ-gjfi of111‘ Northern.'1-1111111111111 Kenya14111111111 (1948,[III—III. p.II. 26).1111 where1-1I'.1_1.I'c he1111. claimed11111111111" that111.111 the1111.1"1111111'111'"Kitale {(6,200-foo1:)fififlfl—I‘IIIIII Plateau"PI:1'Ic'.III“ is111 clearlyIII-”311111.: a:1 residualIc1.iI'.II..I'1I on1111III111the Uganda[.11-1.1111111 peneplain.111c111c11I111r11 Gibson11111171111113 11.11.1311(1954, p.11. 9)I1": 1111.1111I111111E'IIImaintained IIIIcthe 1.111111111111111distinctian ‘111'I'11-‘cczIbetween theIIIc. :1L'I:I—sub-MiaceneI111111".1.'1_"II-:': and1'11".I.I. Kitale”‘ :1I'.:I1' surfaces11I.11'i':1-1_'."1”1 and11111-1 PulfreyIIIIII‘I'c'II” 1113111111-(1960, p.11. 7)TI {IEL'L‘I‘IIL‘IIIaccepted this.11111-1. Shackletan1"‘1-1I'1'_'-I_'"I{II_"II.IEI (1951,111.1111. p.11. .‘1".1'1‘1379 and:11111 map)111.111: 1'111”:'c‘:'.1.11-1.:.Icarrelated theIi'Ic BugishuI1-.1g_11-'1”1'.I1 BedsIII-11:11: and:111.II sub-Elgon11111—1-.I1';1.I:': surface1.1-131111;: with11'iIII the11-1: KitaleH1111Ic plain11:11:”: and:.:'.I:”_I the'1."'11.-". Uasin1.1111111I Gishu(1115:1111: plateau1111'Ic'1111 and111111 asserted111.111.111.111 that111111 they11111;. are1111." all1:I 'One11111-1 11:11.1and the'1I1c same,1.”-1:".I11. IIIIIIand sub-MiaceneIIIII'I—"1-I 1111:3111: in:‘11 age.$11.11. CantaurI‘.‘-1'.-I".'.11=.:I' linesI1'1"..'-1. drawn1II':L'1111 by1'."_'-. Shackletan"11‘1'I1IC1IIII::I:.”1:”1 on1."-1'. a map111-1111 of1111' III:the projected11:'1.11-.'.cIcI'. extensian1111121111111: 'Of111' the1511.1 sub-Miacene.111:—."I.1I111II1".1".I"1-1". plain11.1i11 from:‘1'1'1111 Kitale1111:1111." to'I11 .IT1-1i111'c:EIdoret and”1111..I.I sauth111.111I11 to111 the1311.1 Nyanda‘."1-I'1-'::1.'1.1111 escarpment,11:--I-1.'-I.'.'11.II'-'11"1”1 hawever,III-11.1-1”'111-1c::'. indicate1:1111c1'11c a1. marked':I.I::'.'II”.c:'1 south-westerly11'.'.1:.II‘.11—'.11:11ic1'111' slope1.111.111 (fromI1I‘1'II}TI'I {1.11111116,000 feetI1.':-'i 1111111111'1'111alang the .'-.1.‘1-11.".edge 1:1‘51‘1I-T'.'Ofthe phanalite11111111111111”: autcrap111111111111 to111 5,500T1.."".II1I feetI'cc'. in111 theI111" sauth-west1111LI'1‘I'1-11 1'1-'1 carner1'-'.'Ii”:II::I' 'Of1'.-1‘ IIIcthe area).:II'c:-. I. Sanders11:11 measured a distinct1.111111111-1: nartherlyI111:'II1-1-1 'I=-.' camp-.11.”I.1I'1_111.'III1':IIanent 111‘af 11.11.1111."slope (fromIII-.111". 11.21.11} 111.": :II 11111-1111. 111'11.I1_Ic I11 1'-..—‘1{!.I I‘c 111”.”11'1'. 1111‘ [111.11.111.11] :IIIII c1”11.'.-1":'11_'-.'. 1111111 1111: 6,200 feet at Haey's Bridge to' 6,400 feet west 'Of Eldaret). and evidence from the Kapsabet111-1111111151 area'.':i”--".”1 I-"IIJIIIIII'IIII'.canfirms I1I11".the cxIcrI11'1'13Iextension 1111‘'Ofthe11'111' bevel1.1111cI 11.1”to' the.I "-.1" 1111:1111sauth 111111with 1111111111similar1' 1.11111c.slape. A.1‘1 1.".I'I'11c111critical 11111:»:piece 1111''Of c1-i11.IcIII'-"cevidence inII1 I1II:”:c"1-1'.I-.'I1111'11Shackletan's 1::1111111'111'111'1I1canstructian 11.11''Of c1111111111'contour linesI'111c1. 1.111an 1111”.his r11:-111map 1111‘'OfI111."the 1111I1—sub-Miacene"111111111111". 1111111":plain in11': '111-1'.'.1.Ic-rr1western 1111-1111111Kenya 111is I'm:the presence511'1'11c11cc 111in theIII." Nyando.‘1”:111111111 1:111:111'111-escarp- 1'1I11IIIment III-”II'IIInorth 1'IIof ‘.'11.'I[‘|£1,‘1I'1CI[‘Sanghar 111''Or 11:11an 111-1111111111autcrap 111‘'Of I'-”1lacustrine1'1'1LII”-1II”1III1-11. limestoneIIII'II-1':1.1'.IIII;1 :11at 1711.115,70011-11 1“cfeet II-ig.(Fig. 2].2). ‘I"11i.~1This isi1”. c111rc111cl1-11'.i:11.1'I:11:'111extremely similar to' 1.111111111111111autcrops 11.1fc."11'.-1.1'Ofearly Miacene111111cc11c 11:111-11111'11111limestane 111at 1.111.111c1'a lawer 1111111111level 111111111111'Outside theIIIc 1.:areaI'c11 111to' theII'IL‘ 111111‘1'1.sauth, 1.1-"Hid":which CI-IE‘Ican I11:be 11c1111111111r1111.demanstrated"1'1 111to' lie11c 11:":an IIII:the 1111131—sub-Miacene311:! 1.'II”-I::' 1I:.' 1.”-1111111111."surface I 8”If.- in'1.I1 111L1the 1111.111floor 111'of 1111:the Kavirondo11511111111111.1111 I'1'1IL1I1'Gulf 1'11'1rift valley.'."1111111'. 51111111111111Shackleton 11.11.11.(1951,:JI p. 1111111366) 111.11.11I'11111.assumes 11a fault1111511 1'1-11.11with 11a :111'111'.'throw 111of 1111-111over 1.11111111,000 1‘11L'Ifeet between11111111111111 11'1L'1'.L1these 1.11exposuresp115111'111. .11of limestone,I— 111111111 111'. 111111and 1111211111.accepts the1111-: 111111111height 1'11”of 11111the most11111111 11111111111111northerly 1'1-111111111111outcrop 1:111as 1111an indication111111111111111 11111111111111.11111of the height 111'of 11111the 1.1111-sub- Miocene11111111111 surface11.11.11 in111 11111the 1111111|1L11'I1.southern 111111part of 111-.1the 111'-111.area. 11111111111111:Insufficient'1'-11111111111111 detailed 1.1111111work 11.111111.was 11111111:-done 1:I_-.by 1:11:the= 1.1-111....writer- I"I" :11'in'I. 1this1111.. 1.11111part1- - 1.1of1" 1111:the' 1.111111...-area.1 111to 111111I1111'1confirm”- .11—or 1111.11.11:.f'..—..disprove. 1111.1.this7.. 1.11511115111111.suggestion..1. .' T1111The 131111.only 1.1111111111111111peneplain bevel'11-111.111 1111111111'1'111111Igt11111111clearly recognized '.I.-'1-'.'11111within 1111:the Kapsabet1.111111111111111 111'-:11area 1.11is the1111- southern.-:.1-.'.1!1I.11'11 111-111.111.111.11extension 111"of theI111: ..11'1'1'1'11'.'L'-surface underlying111111-:11'11.-111§:1_ 11111the 1.1-'11111111'11western lavas11111.".11. 1.1.1"of 1111'the Uasin[11111111 Gishu11.111.15.111: plateau,.1111111111.1141111115111:1- --I-'I..-' - whichIf” is: the'11 extension1.111111111111111-' '11- ---r of“111-I the'1'-'111111111111..111.Kitale'11-"11. 11.11.11.plain.'1-I- IV-SUMMARYEV—Sififilliflfl'f {1'1"OF TH}?THE fiGEOLOGYiifllfflfi‘i" AND1111113- {1EGEOLOGICALfl.[..i.}{1lf11'111_. HISTORY[1111111131111 {1111'OF THE-1THE AREA11111111111 TheT111: 11111111.".oldest rocks111-111:1. 11111111of the '.1'1'1':'1.area are111'1: Precambrian.111'1'111I.-.11 in111 111.11age and111111 111111are represented1.111111111111111 by13111111111111.1114gneisses 1'1"of 1.1".1."the Basement11:11.:11111111 11'-131:1System,111111. highly11'1-:1111' metamorphosed:1'.1.'.111111'1'1111111.111'11 1111:1111lavas 11:“of 111L'the 11'1-111111111111Nyanzian 511-111-1111.System, 1111111and intrusives1111111111111. 111of inferred1111.11'1'1'11 post-Kavirondian1.1-1:111:1— 11111.111.1LI.11' 1"1_'_1._'age.L_'. They11'1-111' 111111111occupy :117111I'11111'I'I'1111L'1j.’approximately 11.11111one third111111.11 ofL11 the111-L1 1111311,area, in11'1 1.1:the 11.'west.11.1.1. A1'11.11.1111111111'consistent111 1111111111131.ba;nding 1111of 1111111111111different 1.111111111111111.gneisses, which1-1'111L'i1 111111111could 11.11be related1111111111 to;11. 11111111111115;differences 1'I'1in 111.11an 111'1g11111!original 1.1:11111'...11'.."11I"I.'sedimentary '11111'11':111..1.111.I1.succession, was11.11.11”. not':-.1"1 1111111111111detected 111in the'11'IL' rocks11111111. L11"of the11; Basement1.11-11111'11 511.11.111.11.Sysem. Well-foliated'11-'..'11—11.111111.1LI biotite11'1-11I1'11' gneisses1111.11.11.11. L1"of the1111' 1:111:11I'111central region11.121.111.11 11111111111about Kapsabet11111131111116 give5:111: 1.1.1:!11'way both11111111 to.11 north1111:111 111111and to111 .1.L1'.:I1'1south to11'1 more111111.: highly111111113: 2111111111111granitized :1I1L1'and leucocratic11'I.:.'.'I1-L'I'1111I.'.' 1111112111211.varieties, with'-'.".111. :1a high1115.111 proportion111'I1I1I..1I'1:-.11.'I ofI1: microcline,.1111L'1'11L'1'1:111. negligibleI1cg11111111-i foliation1111111111111 11111.1and '.I.a 1'_I.:"1'1.'II'1I'.'1-I11granitoid texture.1111:111I'1'1'. The1'11: 1111111115111.outcrops ._-_.j'of Nyanzian1'111'1'1111'211111 rocks1'1111111. in111 the'111L'111'L111-11'1'area are 1.1111111small 11111:!and 1111111111111usually poorly111111I'1'1- exposed.1111111111111. They1111'; are11:11 preserved{.'.'-I'1.":1I.."-’.' "1'-1'1 on1111 1111'the Nyando“1.1111111111111111scarp 11.1.as fault-blocks1'1'1I.I|I—'.'1-1-:1.'.'1.1.' in111 the1111'. 11111111:complex1.1-1.1.: structure1.11'L11'111I'L at the1111' intersection111111111113111111 of1'11 11111the Nyando71.111111111 11111.]and Nandi711111.111 fault111111. 1.311'1111111111.systems. 'I'1IL1'_-.-They 1111111212111consist of111 111121111111sheared 11111;and altered2111111111 lavas,1:11:11... mainly1111111111: 1.1”of basaltic1.11111'1I.|11:.' 1.1111111111111111.composition, highly11ig1111' injected1111111311111 1.11111with quartz111111'1'11.LI' veins.111111115. It11 . proved11113111111111 1.1111111111111111:impossible toIILI .'1-11.111111111111111demonstrate 1:1111C111.1.1111'111'conclusively 21111the 1111-:age relationsI'L'.'1'.111L11'11.' between1.'.-'I.'I1-'.' '111'. 111111the 1113-1111111'1111Nyanzian 111111and the1111: Basement[5111'1’111'111111 .1111'11113111System rocks.I'U..'1111'1. T111111The 151111111111granite in111 1111'.the 11.1.IL1'111—1I1':.1-'.-'.sQuth-west :111'1121'corner 1.'1-I:of 111.:the 1II'1'11area 11.is 1.11111131-widely 111I'1'1111I-11variable inI11 L'L'JH'1[)[.1H1[1I.'=1'Icomposition :11111and 111111111111.texture, 11.'1-:1and 111111115owing 1'11to 1111:the 111111111111thickly forested1'111'1.'.1.IL'I'.1 1111111111nature 111'of 1111::the 1111111111terrain 11.'its 11'-1111.11.11.11contacts 11.'111'.with the111-1' 1.1111111111111111:surrounding rocks1111.11.11 111'1'1are 1111'.not 1111111111easily 11131111'11111'1111.determined. It11 1'encloses.1111 11111.1. 11111111113111.1111a number of patches1311111111111. 1'11-of Nyanzian“'11—:1I'E1111'1 lavas,111111.11. 1111'111111apparently111. 11.1.:as I'111'IIroof 11111111111111.111111'11Ipendants, indicating '1'1'Iutthat it111:.:.'.Iis at 11".111'.least 1111.1—1'111-‘111‘11'1111'1'1post-Nyanzian .. ..' ..'...- 1- _.- I-"...'.... 11. - 111in 111-111.age. It11 11'-1.is, however,|.1'.I'.1'I.L'1.-'L'I'. 1'111'11111L111Li1'.continuous 1-111'11'1with 1.1111'11EI1'1.granites 11:11'11'."furtherI'1'1['E. 1.1-911..west 111111that invade1111111111 Kavirondian111-1.111111111111. 1.111111-11111111111111'1'111111'1'.rocks and is, therefore, 111111111dated 1..-1.as post-Kavirondian.11.11.1-11.'1111'11'1'1-1'1111111'1. 'I']1.1.1The 11111111111eastern 11111111111111:two-thirds 111of the11111 1111111area 11::is 1111111111111covered by1131 '..-111111111111volcanic rocks11.1.1111... 111'of '.1'111'111'11'311Tertiary 1131age. In1:1 1111'.the 11111111.north, 111-1'1two major1111111: 11111111111131phonolite flows11111.11 .'.'11I'I.can 11'11:be 1111.11I11_’11111.11EL11distinguished. 5111111111Small 11111111111111.1111.exposures 11'-1"of 11.111tuff and1'.I11'1 111.;L1ILI11'1111'1'1111'.agglomerate indicate111111111111 that11111: '11a pyroclastic{11111111115111 phase'I'1!'1:'1I'.L' preceeded1.11'I.'.'.:.1'L1I:.1-11I:1 the1111.1 111115111111original 11111111111111phonolite 11111n11111'1l11'1.outpouring, 11'-111and :1a 1.1r1'11|:1:'111"11111'1'similar phase 1'.IL'L111"II:'.11occurred between1111111111111 1111the flows.11111111.. In11'. 11111the 3111111Burnt 13111112111Forest '11I'1111area it.: 11111can 11:111111I1111111'11'1111be demonstrated 111-111that 11111the upper1111111: 1'1_1.I|L'1111-.::volcanic 11111111.rocks 1'II'of TinderetI111-11':11'111...11'L11'1111overlie 11111the plateau1111111111. phonolites,11.111111111111111. 11.111111:while 'I'111I'111111'further 11111111south near1111111 11111111111111.Lessos, it 111111can 1111be 1111111111111shown 11111that 11111the 1.111111111111111phonolites succeeded1.1111111111111111 11111.1the 111'L1pii1111eruption 111of 11111the 111'-1.1111111111111111.111111111111111major Tinderet nephelinite 11I111'111I11I'11'1'1111.agglomerate 11.111111111111111.(Shackleton, 11111111.1951, ]'11p. 11111111.368). In[11 11the.11 111111'1111111'11111111111extreme south 111.1the latter11111111 11.'.is 1111111seen 1111.111;resting 1.111on .'.1a 1h111.thin 1.1111111111111111sedimentary 111111111.series which,'.11111'1'11. TIL-1111'near 511I1g1111r.Songhor, 11.111.has been'11-1.11:1 proved111111-1111 to111 111'be L11of Miocene?111111'1111'111 115.111.age. T111The 1.11..'L'L'.~'..1.111I11succession 11'1in the[1111' Tertiary1'11'11111'1111111111.rocks 1'can'11'1 beI11: 1.11111I11'111'1111‘111summarized 111'.as follows:-1111111111'.1:- — 'l'1=I111'11111'TERTIARY ROCKSR111'IL1111II-"I'1111.OF THE KAPSABET11.11111111111T1'31111'.AREA I I Formation I IHFWJ 1:111'11111111111 RockR1111; T111111.Types 5111111111Source LII'of 1111'111111Origin i Map1111111111 ' I I I Symbol5111111111 I I i 5.'...I'I '1'111111'11'11Tinderet phonolites1111111111|111111 . 1.1111111. 11111111111111.1111 T1I1I1'.I.:I'L'I . _ T1..-']1._; .. I Lavas predominate TVP4 4.41-1- 111111111Upper 11111111111111volcanic rocks111111.11 1.11 1.111111. 111'11111111111'1'11111 Tinderet'I'11'111'1:I'L1'1 . . '11-'11.TVP3 I of Lavas predominate I T1111111'111.Tinderet. Tinderet Tvpn1'1-111'. 3..1. Uasin[11111111 {11111111Gishu phonolites1.111L11'IL11111'11 ...! L1'1111'L1'.Lavas . . I Elgeyo1311;111:1111 1211.11111-scarp T1111.TVPl L111'11I:'11L'.II1 '."'. T1111:TVP2 2.3. "1'111111111111111111""Nephelinitic" 11gg111111111111111agglomerates 11'1-1111111111111 111111... 1111111111111 . . 'I'1-Tv I direction? Pyroclasti rocks Ii Tinderet I 11111111111111111121predommate. . 1.1. Miocene71111111111111 lake-beds.11111111311115. . .. . ! LimestoneL11111111'111IIII: 111111and TI'I'ITm I 1.111111111111111waterlain 1111111.tuffs. T1111Tmf 1 9 Recent1111:1311: 111. 1111131111111deposits 111'1of gravels;.-_1.1'- L1.'11 111111and 11111111:alluvium'L:I1I 11111are 11111not 1:1-111311111151:extensive 1:1-11'.but 11a 11'thick11IL'.'11 red11:11 111111soil 1:111:13:cover L-11L':.1'1overlies11:11 EITCEHHEEgneisses 111'of the1111': Basement11:111'1:I111:111 System'11-:11'L11I in111 the'1111: .'.1.:'1::I.area north:1111'111 L11of 311111111111.Baraton, and111111 a11 {11:11:11deep mantle-1'L L11“of redI'LL'i .1'1'LII'[soil 111.1111also 12111111111covers 1111.11:E1much of111' 111-:the plateau.1111111L11LI. Black-cottonHILLL'k-LL11111I1 1111'.soil 11:111has 11'-'L"1'L'developed' 111L=.1'.]1_11'locally in1I1 regionsELL-.1111. 1'1."of 1111111poor drainage,1111.1i11.'1-11'111'._ ["111the largest1111;111:111 Lexpanse11111111 1.11.1111'IL1'11111bounding 11'I1:the 111111'1111:L11swamp" L1".on the Kipterges1111-1331-1111 :11'111and 11111111111131Kingwal rivers.1'1'1--1::'.~.'. ' '1-11 - r 'r ' -' “hr-“11 . r.-' -' -."'.!1L1"111.".1".r'1'1'1SUMMARY '05:OF THEI11“; {1J£_'1.-'£.':.I'{.JL'LGEOLOGICAL."LI HISTORY':1111511114111"!I - OFUi'' THEIl" 1"'I1f~'.'1E'_."1.AREA- ' Frll The1111': geological11111111111111!- '-: 11 I 2.111.111.11-history.--.--1-1-_- .1- . 1-1of1.: the1111 11L-::1.1':1111area can be11L' -.. 11111111111111.11111111summarized-. -.- . . as. follows:-1111111111111:—' - - . Early1'1'11' .111'_'1= Precambrian1"1'1-'L'11'1111 ."11".1'1:1'1'I "'1.. ..1 r '11. {111111311Geosynclinal1'1111-11LL1'1L1depo&ition2-1.'111'111 111'of :1a fairlyI unifurm1:1111'.11111 1-IILL11-11successionL111 1'11f51'1'11'11-1111'1'i'11i'13of semi-pelit!ic1 11111111111111.11sediments- -' - 111.of 11111311111111.3111the Basement 3111111111111-System. 2. Emplacement1".11111'111L1111111-11 111'of LIL-111:3.dykes. 3. flOrogenesis,l'flgfi'flfflh. in 11111111131which 1111:the :'L'.1.i1'.'11.1'1results 11fof 11'-11.111211]several 1111111111111'11'11‘1111:metamorphic 11LL1L'L1'1'1L1'1processes L111:can 3:11:be recognized,T131311LE."1|EE11| 111'I1:'11which I'I'I:1I'-'may 111111-11have proceededL11'LILLLLEL11 11L]1:1.I':11'1:111-'.separately, intermittently1111L1'11'Iitti'111111-' L11;or 1:11111111-‘11contem- poraneously.12113111111111.1111- ‘- l " ' 1.1111'1'1RL:11111I::11(a) Regional Metamorphism,:11-1L'1:11111.1:'-'1111.-11:'1_. with:111:1 1.1I'production11111111111.111 mainly1'1111111'1'1'11.11-1111'111'1'15'.of biotite gneisses.“1.111131111111111 '11-1'1}(b) LimitedI'LL-.LLL'LI 1111mobilization1111111: .11 locally,{11111111. and111111 1111-alkali:11111' metasomatismn1LI1111L111-111:-111 to:11 form1111111 11112111111111.migmatites, LI':111IIL1'ILI 211.111.111.111 111111 11111111111111. granitoid gneisses and granites.1. 1..4. Injection1111111111111 111111111111.of quartz and:11111 pegmatite11L-111111111111. 1111111111.veins. LLLIL'L'Later 1".1'111311111'11'11'1'1'11'1Precambrian 5..1. Extrusiveif. 11.111111111'L 111'.phase,'1-1.~'11'. 1111111with 1111i11111I1'11111outpourings:11 L11"of I'LL-1111:1211Nyanzian 111111111...lavas, 111111111}:mainly 11115111'1111basaltic 111in LL11'11—com- '" 1.1511. 11.1111- position..rI-HJ .. C) 6.-.-' Orogenesis,1"11gLI1-1'L'5111. intense11 15.1.1111: folding111-]L'1111'1. :1111L1and faulting.'1'.-111'11:I1L1_. :1” 7. Minor:Ir-II 1.11.111' intrusive1111.111111I11'L 1111;1113'.1'.'I-1=.1phase, with LI'111'11'1'1L':emplacement11:11.1 L1fof LL1IL'111I'11L11epidiorites {1111:(age relative1'1311111'11'1: 11.1to 111'111111L11granites uncertain).1-. '_' 113111111111]. “'2- '_ '_ . '._ _ ".1 11.8. 7'11"!Major:.1_1L1r plutonic171111111111L phase,[.1'}"'1.'_L3'1-2'11 '111'with11.11. -:Iemplacement..1.'1.. 11111-1111'1L'II1.1” _ . L 11.of11"."the1:11:.. 111111-11511111-IILII'1111L11post-Kavirondian. .' - '. g:111111:::'1.granites.. ' '11.9. 51.111111Minor 1111111111111;intrusive phase,111111111. 1.11111with L311'111111LL'I11L111emplacement 1111‘of L'1L'IIL'1'1111'1'1dolerites 11.1111and gi.giant1111Lquartz.1111111'. '1L'ILI':-'.veins. 10.1'11. 1":111Faulting,11.1111. 11111111111111;affecting NyanZJian1.1111111111111'L1L11'1.rocks 1'11"of 11'.Koyo111.111 111]]hill. Late'11-'11' F.1'1'L'11'1'1'11'111'1'11'1'1Precambrian 11111.11rand 1'1'1'11'1—F1'L'L'111'1I'.r.'.II'1"111'1post-Precambrian 11.11'. {11111111111111Quiescent period,1111111111. :1a great.great lapse11111111: 111'of 1111111time that1111111. 11.11.11has left1L1’1'1 1111no 1'L'LL1LLfrecord in[11 111.1:the 1111:3121rocks 111'11111of the :1.area,'L:-1. 111111and 111'111I:11.1111111terminating 1'I1.in 11111the 11111111111111formation 11.11111:of the “high""high" 1:11:1111111l1'1111peneplain {211111—(end- {.LL1E1LLL1LEW.Cretaceous? ). Tertiary'.1"1111'1'1'11'.1'_'.' 12.E7. Uplift,1. WIN. f'LIHLfollowed111111;. .11].by the.f111'formation111.11: L111 1'11'1111L'11'.111—"1.11111.1r'=of the sub-Miocene peneplain.11111111111311}. 13.:1. Minor'.‘-”11111.11 1'11:L1111I':::'1'1'L:1rj-1'sedimentary phase,1111:1211; with1111'i111f111'1111formation111111. of111' the1111.. Miocene111111.11 1"1'.L-'-:—1..LL'3.-'1.lake-beds. 14.'1 -1.. Major3'11'111'11' L1111'111'111111:extrusive phase,11.151111211111111with 1111111111311.eruptions fromI'I'L1ILI LLI'L'LI'111—1131'11Lcentral-type 131111-1111cones like11'-LL: T111dL'LL'L'.Tinderet 11.-111and from1111111 1111111111111.fissures, 111'.as 11111111with the11.111 plateau111111111 phonolites.1111111111111111'. Upper{1"1'11111'11' Tertiary-Pleistocene'1'1'.1'1'1'1'11'}=—1'-"1'1'1'.'.1'1'11'1'11111 (?)1' '.' '21 huh-II '_J': 15.. 'i'LLIL1-I'11LTectonic upheaval,11111111111111}. with'111'1'111 1111111111301:formation 111'of the KavirondoK1111'ILL1111111 Gu'lfGulf RiftR111 '11'1111'111'YaNey 1111.1".and rejuventation1'12j1l1'L11111’111'111 111'of 11"11:the Nandi311111111 L.~:L:.'11'11I'11L.1'11.escarpment, 111111111111and with '.L'IL'1-11local 1115111111111:dynamic 1111:1111111111’1111'11111'1metamorphism of111' the11111: adjacent11L'1j1'1-L-L111 rocks.1'11Lk11. 16.:1'1. Extrusive11111111111111:11h111111.1111-'II11phase, with eruption1111111111111 111of 1111:the uppermost11111 1LI'11111111 Tinderet1111111111111 11111::11111:volcanic 1111:1111.rocks. '.1".1111'.11"1'1'.1'_1_1'Tertiary 1'11to F1'1:_1'-'1'1111-'Present £311.11:Day 'IT'.17. Erosion,1-'.I'11.11'IL1I:I. 111to 1111111form 17111111111111present 1111111;Eland 1.1111'I'11LL.surface. I --' 10I 1'1 V-DEJ'AILS11"—DETAILS OF[H3 GGEOLOGYEflLUfl ‘1 1. 13113311111111Basement 53.313111System T113The rocks1113113 1.11"of 1113the Basement13113111113111.1133313111System in111 1111'the 111311area 1.1131;lack 1113the 1'regional31.11111:11 1111111111113banding 3211111113:—charac- teristics13.111311331111113of the 3333111111system in111 many1'11:1113' 11111111other parts315111111111Eof Kenya.11111113111. ThereT111211: 111111.1131-111'3'311'11111111.11111331111131-are no crystalline limestones, 13111111111131-quartzites IZII‘or 1111131”other 1.111311111111313distinctive 1.13‘1I111’11‘11'311‘I1I31'Imetamorphosed 31111111131113.1111.13111'31-11111133sediments. The prevailing 1111:11rock type13-313 was33-113 31111111111133probably 113113-111derived from1111-111 11a 11111113fairly 111111uniform'1'11'11'1 33113.3series 11."of 33111131311113semi-pelitic 331i11111'11‘13.sediments, 33.11111.which11111313-3give :'i.-'3'.'rise 13:1on 1113111111111'31i1i3'111metamorphism 111to 331111111113various 11111111311banded 111111and 111111111113:homogeneous11111::--.3 111111113biotite 111111and 111.111131131111-:.'—'I.'II1'-II".L'hornblende-biotite 1311313333.gneisses. These111113133 1133-3have 1133113been 3111133111311subjected to:11 1111113111111.injection, 151'.-disruption311131111111 111111and regional11.11111 1.1. 71131113331311.3111.metasomatism. Locally,1.1133113.1111:111311r11:1‘113'.11metasomatism h113has 113311been 1111111133.intense, 33:113111111'1'1'1'113when the rocks 1133111113assume 11a 3131111111granitoid1.1 appearanceapp-3 3111131" .11111and lose111.311 the113 11131last indications11111133110113 of111 their111.:i:' 1.311111111111111311:113-111.1:1sedimentary origin. In the1113 1131131better 11131111111111foliated 1111:1113-1113:11-exposures the'13 general1131131111 31111111:strike 11f1.113.11111111111'11.'111"'33of the foliation varies 'between1131333131. north-south11111111-31111'511 1111111and northwest-southeast,111111.!1'31-31 311111113131. 511111and lineation11113111111111 1'3is 3111113111113generally 31333.1steep 111to 1113the 311'II11—3'1111south-east. For["1111 the1111' purposes3111111113311 111of (13313113111131description the1111';-1111331111111'133'3131'11Basement System rocks15.13133. 1113'of 1111311313..the area and1111-. rocks1:11:31: 11111331111111111111111111111derived from them can be11.1- 1113111311111111111111111111111.1111:11.11111313:——--divided into the fallowing groups:- BASEMENT113111111113 1' 53131331SYSTEM ROCKS133.111.3113 (1)1'11 1:Pelitic1111".I." 111111and .1.'1"'111.‘--I1'11"1"1"1'1:17semi-pelitic gneisses..3'I'I1'1".3'-.'1'.I'- Biotitei3111-1111? 111131131133gneisses 11111.1and banded11:1n-1.11:1: 1111.'."I!.'-'.'.1"1I1:'1hornblende and biotite111111111: gneisses.311313333. (2) Migmatites.11111131111111.1133. Biotite1.11111111- migmatites11113111311133 11013111131111;11113111311133.Hornblende migmatites. {.1}(3) {"_1.I'1'1'.r.'.-".-'rI111rGranitoid gneisses.1.11.13.13.11 1'. DERIVED[1111113111 ROCKS11111113 1'11(1) .'I.I'1"I.I.I'111111I'-."1'MigmatiticL. {'_11'1111-1'131Granites '1'113The 1111131total 1111311113133thickness 111'of 1113the 11112113.rocks 111'of 1113the Basement11113111113111 53-31311".System 1r.-in 1111:the 1111-11area 13is 111.-1111:1111difficult 131to .1.-3.313113.assess 111111and 3113'any 11111111111111:estimate 11.11131must '.'13'be 1.111113131311311considered 11131113:higMy 3111'112'11'1'1'11i'3.'1':_speculative. 1111'.The 333111111section 1.111on 1113the map11.11131 runs:'11111'. 13.31311111311111113'13approximately :'11at 1'1311111111331113right-angles 11'.-to 1111'the 17.11113strike 111‘of 1113'.the 1"1'1111111111'1fOlliation 11111.1and 1131331137:between 1111'the Kaptumo-Kapsabet131113111111111-133313311151 13.11.11and Lessos-Nandi1.11.33113-N1111111 HiBsH1113. roadsI 1.13113 311-11113neaI1ly 3111112111vertica'l 311131311133.gneisses 111111111131outcrop 111-.".11'11.1111.'11]13-'sporadically 11'1'31'over 11.a 1Ii3111111'1:distance 111‘.of 133313-111twelve 1111i33.miles. If11' 11"-1'1the 1133131-degree 111'of 1111111115.folding fl111311111311illustrated :'.1in ‘-.'I1.'.'the 33111111111.-section is13: 11333311311.accepted, 1.11.i.e. 11111.1the 111111112111amount 111of 1331325111111repetition 1'15"of 11.1-11.1:beds 11111:due '..-'1to isoclina:l1311;11:1111 1111111311.foIding is.3. .":'3as 31.3133331311.suggested, :1a 111111]total 1111311113333thickness 111"of 11111.11:some 3.15111125,000 131-1feet 111'of biotite"131-1113 11'11‘1and 3'.-"111111111511granitoid 31:11-13:33:gneisses 1111131must be‘1: involved.1113'1‘113'311. I -|31"3. .- ...,L . I J. -.-I . ' T ..._ . ...-J“ 1. .._1_ . ' _. _. The1111. rocks1111.13.1- in-11 the1151. north11111111 of1‘1 the1111. area-.L-'.-_1 1.3131.have 31111-31311suffered more-1“:"1-111' 3.3.1.3.-extreme1'11: metamorphism11.1.1.1.1'.".111.'1:'311.'133:13. . ' ' and331331 .'.-. ....3..-..- -.'---..-.. .- -:'- '1.- - 1' .5 1. ' ...... 1'-.'_-. _ .' -.._. .... _ ' ' ' metasomatism1311.15.11'3151111111'111131 Eli-1'11and Eldisplayfip'tlj'r' 11.11a!l! theL-H'. C11c1rLiL1LEA‘t1113-I‘1characteristics 3"1.of migmatites.nl1i..5|‘:.llT_J-.IE':':. TheI111: persistent[51131111111111 high1'1'!":II-1 I €11 '11 '-'.Fr'I .- - -" r I1 - .- --1. 3.3-3'F 'F'3. - -- _.--1.:I d- . ' . ' ' I '..-I plunge.1.-111.13. ._ 1111:1113va'lues ofI11 311.111.111.113southerly- Iineation1:1.11.1.I-'.1:1 throughout11'. 21311.11:.._ the11.3 :1area,31:-_1111.-.-1+1~.1-rindicating11 ___ 3..steeply3.I.'_‘|..1. 31-31 plunging-3.--_-.11- .1:_.._:__ 111111fold 111133.axes, 3113:1331suggest that11111.1 the1113 311111113111southern 331311311111extension 1'1."of 113.31.these '.11'11'11r11northern 13333.35rocks underlies.113113-1-3'1131 11;.-the biotite"-11'.'-.'.11.'.': 3111313333gneisses in1.". the111.1: 31II.1I.1.south. A1'3 northeast-southwest11111111333:--'.-._3I.I'.i'.31.33:. section33111111.“. through11" '1'-.1315'. Pire115.113..cuts-' 1.1- nearly1'1.” '1'. 16"1 miIesI"I1i131'.1. 111'of rocks131113.32. 111.of H:the'1. Basement. 1131:11I:.I. '11 System,L1313.11.11". involving1:111:11. '11:: 1'.a 3-..'..'-.:'.'-..3:I.'-1.succession of .1.”.at 21:11.31least 11"II20,000:1 '- feet1'-.-1 .11'111111111.-1111.111111-711.11111511113-1'1111111111113111311133.of biotite and hombilende-biotite migmatites. I'lj-(1) P111111PELITIC 13.1311AND 5411-:1121-1111'21'1'SEMI-PELITIC 1'11.1.11:_31-'_3.GNEISSES Biotite1111111113 33313333gneisses 111111and banded'.'.'-31111311 biotite1.11111 113 11ndand 111111115111111113hornblende 11113133311gneisses 1133:1113-occupy 1'1a large|:31'3.1.- -.'-areaI ..rnundaround K11313111131."11131.133313111111151Kapsabet. Their separation 11"1'1on 1113the map111.-'31 may11.1113 11.1.11not be11:.- justified,11131111311. :13as 1113the -.1r1_-_.-areas marked33.133.31.33 :11:as 11113113113111occupied byb3I banded111111113d 3111313333gneisses 111'11are 331113131.where 11111311311133exposures .1113are best1.111.131 1133-31-11developed,I'1.11'.'. 1111'for 1.3.1.111'11example '.I".in 1111'the region11.3;11'111 1'11of 1113:the E11:13'.1'.I.1.-1'Songhor road-cutting,r11311-1'I1111-111. 3'.where1111.13 31351311171erosion :'.5is 31133-3}sufficiently13.3.3313. rapid“33313-3 3,.to 313.3121.display t- 11 a:1 good$111111 sectionseetiert ofef the morethere readilywe-I1iiij. weathered,I.I.Ieati ere11. and11:11.1 therefore normally1'1-11:11:111111' iless11:12:: frequenrlyfrequentif: exposedexpeaed units.1111111- The gneissesghe111e1 are notnet weHI.I.eii e:1p.1_':e11exposed along11111115.r the major111:1j1'11 streams.I:tre:1111:~. as1:: vaHeysI.'.Iiiie'1'I: haveh1'1I1-Ie reached a11 matureItteture state,flute. and their 'bedsbed: are typicallytg-Ipieeih; cloggedelegged with reeds.reed: The gneisseset1e1I11:e.I1 are bestbest dispilayed1111111111Ie11 towards11.111'11r1:i::. the1111:: headsheedI: of1:11 theI‘Ite minorminer tributaries;:rEhtItnrfeIe on1111 the interfluves1:11er1'111'1e11 there isiI: usually11:11:11i a:1. substantia'l1:1hstr1111111i I:I.I.iisoillcover1:11.1Ier and:11'111 exposurese1p111111re1'. are:tre r'eI.I.'.few. The'I'he typestype-I. I.Ii'of gneissesI_.I:'1ei:I-'..I:e:~. encountered1II'Ie1ILIt111-1-1‘ed are 1:1:I'1I'111Itcommon in111 the Basement11111111111121. SystemSyaten: of1:1 KenyaPie-:12. and.111111 have11:11-11 beeni'IEett described11eI1e rihed in1n a:1 number111111111er of11f previouspre1'111‘1111 reports.rep11111:1. In111 this11:13 areatire-'.1 they are rarelyrare-'1': homogeneous11111::1Ige11e1‘1L111 1111-erover greetgreat 11111111111331.distances, varying11111111111 in11': graingreitt size,51121-1. proportion11.111111111111111 of111" mafic111:111e minerals1‘1'111‘11'1‘11111 .11111and degreeeiegree of11f foliation.11111111112. The"1' he last111.11 two111.1 factorsfeeter:I.-'11'e1:1t1II'I'e|:1tI.::.'are interrelated. The higher thet.'.I'11: proportionerepe r111111 of1'1-t" mafic111:11'11: minera'ls,1111111111111. usuaHy1111111111 biotite,11:" tite. the1:11.: moreI'IteIre pronouncedI1r11111'11::11:.1I"1 the‘Ii'-.e foliation,t':1‘11'.1t:t:-.I1. while111::Ie the:he more1111.171.- leucocratic11:11:11.1:1'11'111: the1111- r111:.'-..rock, 1hethe more111.1'e homogeneous111.11'1'. 113111111111: endand the moremere resistantre::1'1.t::1:It tot1: weathering.I.Ie1I.t'Ier:ne. The'11": gneissesI.I:11-1I1I1eI: are:tt'e e1-'e:"1-'I1I:i'1erI.I.everywhere highly1'.-111.1111 injectediIIjeeIed and11:111. 111I1rt1g111'11.disrupted, and111111 approachingempreeehine the south1.111.111: the foliationt-.I‘: :1':it'-1'. becomesi'II..--'..'I.'1:'.II.eI. less11-111. pronounced[31:11:11.11111.‘1'11 11:111.and 1:1.ethe rocks1111:1111. more:1'.-. Ir— highly':'.::-.I5'.‘-I."felspathized..e: I.'IJI'III1L.’ There'1".'1.-.-1I'1.I is':.'1: no:1-. evidencee1'Itienee to1.11 suggest1:111.Iee:1 that111.11 thisthI'I- isiI': a:1 consequence:11111e11'11ettee of111' the action:1e:‘11111 of1.11 fluids111111113. derived11er1'1e11'. from111111.: the graniteI.Ir'1I11'111e 1111-11that invades1111'1111e1111em11111131them in that partpert 11fof the :11‘e:1.area. Specimen$peeit1LeI: :1I-l34/68*1‘1-11"" e1111ee‘1et1coHected frtt-r:'.from 11111two miIesIIIiieI: 111.1tnorth I.'-1of 1.'iIteI111-ICheptet Mission."1-111111'1111-111.is :.a 11'111;type of111 I I— fine-grainedI1t':e-_I:r'111:tet.i 11111111biotite I._::Ie1.I:::gneiss 1‘11of 11i11ewide £1111r::'.:_ttdistribution.111:1. Iti1 tends11:11:11: 1.111e11111erto weather uniformly,LI.:'I111'I:'I“.1}_1'. eree11'1"creating-1_ platform-like:11'1111'1Irrt'1-i111.e -'.-I.exposures,111.11.111‘e11. 11:1on which111111.31: numerous:ILIrtteIIILtn 1I1_1e1:‘-1e11injected 1.1111111?quartz and'111'111 pegmatitepegmatee veinsI:1.'1I1..I1: 1:11—11:form smaHI.I:teii upstanding111111111r11'11111.I ridges.I'11'i1_I.I:'I1. A.--"I. thin111111 112-11‘11'111'1‘1':section 1.11'of the rockHELL 111111111:shows thatH1111 biotite'i'IitI'iie isi1'.t':1ethe 1II1|I1Ionly ferro-terrt‘I- magnesian1:123. 11171 :1e:~:;:1:1 Ittirtet'11imineral present,preiettt. 1:011:11:constituting.L'.I.iI'II..' 1:11I:1esome 15'77. perper I.'entcent 111'of ‘.1'11':111111111111ttt11e.1111dthe total volume, and beingh1-:I'.;-_.I 111of .1a:1 ‘1'1'."|.TiET.j1I'variety pleochroicp1e11e11r111e 1111111from 1.11151:dark 11:11'e-greet'1olive-green to111 buff.he”. .I’I.A 11111111smaH 111111111111amount 11?of piaghteimeplagioclase within"1111‘.11:t the 1IiieeIeiEIIIeoligoclase range:':1:tee 1‘11of 11111111111111111:composition is1.1: present,wee-1:111. 'but111:1 tE‘tethe masst':1:'1.II.:. 111'of the[he rockr1111}. is1.I: 1:11.11com- posed'.1I.1I:e(1 111'of 11111-11111quartz .1rt11'11111'1111and a'lka'ii 1e1:.:1:1r.felspar. 'I'heThe 11311115111}:accessory I111I1e'1':-1II1minerals includeiI'1e111t'1e et111111‘1e.epidote, 1111111111:apatite 11:11.1and sphene.1.1111ette. SpecimenSpeeirrteh 34/109,714 11'1”. fromft'tIIIt :II'.an I.Ittte1'111'1outcrop displaying11111111111111; tombstone-typet.1.1-'1::t111'1e-11111e of111C weathering.1. e:tth1.Ir1111‘1 some1111-11: two111.1 and:1111’ a:1 11:111'half miles1'.ti'I1:I: south1:111:11: 1'I."'I1 -.-'-11.‘II'.ILI'11:etf [1:111:11e1. I.I.1t.‘-1 t1'.t:I:.:111: '::‘.I‘tt1.'T'..I.'1.'. 1.1.1:: '. Jll'L-II..I1. :1 elongated patches with mosaic structure, and grainsI.Ir'.11t‘1.1. exhibiting1."1.i'.‘31‘I?‘:..'1I.11. 111111;:111'111:shadowy 1:.-'.I.extinction. J. A._ 11::::11i'.-'11"1".I':Iesimi'lar type was11.11111111I'111et.found at Mugondi,11111-1. 111:1 five1111: miles11111.21. 111111111131:south of Kapsabet,[1.11111.1111;"I. though”1.11.1111:jII_~1_5.]:.1_1‘-I.'.I_.it is slightly_.Il paler:111'Ier and'.:.I'It: moreIII-1111' fine-grained.11.11-- I.Ir:1i.:1e11.1':'1In thin1'11111 section::1'1'."111I."1 (specimenI.'IIpIEemIer: 34/60)3:1. 1'1”: a1': ratherrather largerlarger proportion,1r11.'11.1.':.':I'. of." muscoviter:1=.1::.'1't'1':'1-I.I mica1111e11 is1.I: seen.I:ee:1 to1.1.1 accompany:I-eetthtpt-IIIIIII the1111: 1:.—1111111:epidote 111111and 'biotite.1111111113111A -e11::IIe-g111f'1-:-11.coarse-grained, coarselyI.'-:111r:1e1}-' foliated1111112111311 biotiteh111'1111: gneiss3111:1111: {.714(34/57)5?} from1"1'111-11 Koyo,111111-11. one1111e and a:1. half mi'les11:11eI-1 southI:11111'It of1.2-: Kaptumo,3111;111:1111. nee-.111again hasit'.I1.I: biotitei'I'. 111111: :1I:as thethe onlyI.'II'11I1I ferromagnesianIHIreIr'I1III'Ie111.1.-'I mineral.1'.:-_1'.:;1- It11; is1'1-.- presentp:L-a_fir1|l_ as:11.- small_..:1I;_.1'i crysta!ls-.'.'.I'j.'.1'~.1'1-'11.I. and111111 isII. disposed'11::11‘1111.'11 interstitially,1111311111111}. or111‘ wrapped”1111:1'1pe11'11.:as aggregaiehaggregates roundr111111d thethe 'larger_:_1r1_r---_r felsparfeJ.1.[_1..1I crystals...‘1'11‘11'1‘1III1. "1Thehe felspar1'ei.1'I_.'1:'1:r is:: usuallyL111L1£111'_I.'LiIi7."-”'.|1'1_'II..'1'.i1'1""1'1111.113.51111j1'HCT1C111'.._‘11.TiZI.'I‘."_T.1i1111IT‘IUI-1EILII.‘-1.'.I:.III'L'untwinned and slightly sericitized, though some plagioclase —... 1 '—'I.' .1 .... . and-.-.'I.1.-.--1 microcline.I.'1e-_1-1.1.:1I.1.I.I 111':are 4-a'iso1.11 present,.-:F~:I1:'I.'1. whileIII1!-1.' the-.:--1.: subordinateI...I§I-._'I.I:.111I.:I.te I.I-.:I.-=.rI..I.quartz has'I'::-.1'1 1113.11.11.11shadowy extinctione.I:'.ir.=I.'.i:I1It and.'-.:'.: rows."11'1'1’1'1'1 1:11of inclusions.11"!11'1115111'11-15-1. ‘. .I" -'..T_.. 11..".'.... -..IH' '..I.:.J. . . -1_ - {3! _IL'....r_1-!L.'1.-' -1"_- if lid-:1 11"... “:1 i'-fi"1i1111._- 13.111115: ifi'ti'gil'. 1'1-“11:31. '11"! htipl‘ieijfit1 [1'1 111.1111. :5 1'1-'I.'“_ I Specimen 34/65 from the Kimonde River bridge,. west of Kapsarbet, is from a very I leucocratic11'1II.‘1.'1:r1111:;‘.1111111.i‘.band. It is.1. 1:121“;extremely"111.111 fine-grainedi13I1.-I--I:-.":'.. '.1'-.: .I."1.-and hasI .--_-.111Ia granullitic:_I::I11.!.:11e texture‘..-1.11.113 with:1:‘.:'. '.1a faintly1::i='--‘ marked11151111111_I. - foliation.TI'-I I.'."1.111111.I -' A9‘1 thini!-111117I section'IL'I’Jl-L'II‘II 1511:“111shows that11.11:'I' the_I..1'.I.' 1'1-1.‘I.rock'1.-1.. .1II.11:I.t.~.consists.. ._u- .11'of. I :1a granular_-_I-".1'I:: ' '.I' I_:L':1I'Iquartz- . .. _ ... . :I '.I. .' .. ..I. _I _1__-_~- _ -_ _ . _ _ felsparEi'DIIF' base11.1.1.1. ‘I’ITII‘Iwith :11..1ttI.re11scattered biotite1.111111...- 1151.1...flecks, in111 whichII:I1.1.."1 are 11.1set irregular:1:'I.I1_I.LI-.'.I.1I' 1e|.'1::1:1.'felspar 1.Ir1::t.-1_:..II.1crysta:ls up to111 1 mm.111I11. 1-1::11'11'111?diameter, variably1.1.1.1."1. untwinned1.I:1I-I:.I'.-.‘Ie1_- or1.I showing1.. .':1:carlsbad,11:71:11: multiple:" 1.11:1" :1I1e‘iand microcline'-“111‘.'I'I.1I"1'"'-I 1'.- II-II- '11 . I J- - 'r ..---u -". ' 'I- I"- 1'1-1'1'1".1. twinning.III-.It_1II'II:. A.1111. 11111111111simiIar fine-grained:II'Ie-_1_.r.1.11.11 3.1111111111:granular leucocraticie.1-:.-..-...I1tLI. gneiss,I__I!1e.Ir-I..-.'..11.1.. a.this1:111: time1'1t1'1e faintly:‘.--.:.IIt|I.-'.I'“ ' 1.1111111e11.banded,l I occursICCLII‘I. 11:1eone 111111and '1':a i'1'.I.11half milesI'I1:|I.:-I: 1111:1111south 1:11?of i'IZ'_:I..’1‘:1‘.1'.'1I.‘IKaptumo (specimen5'1I1'Ie1t"1.'.-. .'434/59)..‘:‘-""I. HereHere: Ti:ethe granularIII".I1r.:1'.-I "E11111? 1.":3'T'E'111‘éi11'1 base consists of1'1:- untwinnedL.”.‘|['I:‘1'.l':."-t.'.‘1.1 potash"'11 11:11:11 felspar{IL-71351: with"1."!'" I -.II.subordinate:1I;.-_~.-11.I-I-Li.dull-14.1.11..- .1.- quartz,I..|-|.J|1‘"_111 |II.1III sparsedr'- I fill: 1biotite|:'_I‘:I:__-1_|H- '1111flakes1.;51'11. fiHingi:I:' III: the interstices.:11: erI:‘11:.'I.'.I:. U:."'.ILI..I:11:Occasiona'l1'11] 111.11111‘.“I|subhedraI iron11‘1111 1'-.I‘e._ore IIgrains--.55:11. 1Lreare present.1'1-11:11:11 " "" ' . n-Lul - '1.-I'd“ 1.'I-:1- inf-Ir _‘_1_I'11'i.1_- 1 1 51-.1 -: r-I.- ;.. 1|. .. 1| 1 * Numbers3111.11.11.11 prefixed“1.1.11-.. by1_ 34/. . refer-: 1... to.'. specimens,1._I111'['.|._.1'1 in-- the-_1:I_ regionalILLTII 1.1. collections._I‘ . I II. of1 theILL GeologicalIIIII I111 .‘I;1I Survey'11.. 1, of111 Kenya.hers: .I -' I 121: Exposures{-'.-11111115111155 near11:111 the1.11: pumping11111111111151 station,5111111111.:a mile11111:.and11.11111 a' haM1111111' north-east11111111—:55! of111' Ka:psabet,K1111511111151. reveal1:511:11 members1115111111115 of11'. the1.11: banded11111111:11' gneiss5111:1515 sequence,51:11:11.1:11:15 and511:1 indicate1111111111111. the1.11: complexity:1111111115111151111'of the111: instrusion11151111511111.111511115:history of111' the1‘11: area1.1-1:11. prior111'11'11 to1.11 metamorphism.11111.111'11'11111.115111-H:.1:Here the111: host-rocks111151—111-51115 consist:1111515'1111of' mafic11111111'1: 'biotite11111111: gneisses1.511.:155155 with1.1.1.1111 alternating1111:1'1111111111 more1111111: felsic115 511. Ilayers,11151115. both11111111. being111511111 typically1111111. 1111. in111 bands1111. 11111.5 of111' more1111.11.15.1'1111111.than a foot1'11111. thickness.111111‘1111555'. A5.5111151111111115subsidiary member1111111111111 of1.1" the1111.1. sequence51211.11511:151'.'.‘.(34/70)J..- T111 is15 a11 finely1111:11' layered‘11-1151111511 rock,1'11-:15. with51.11111. narrow1111.111551- leucocratic1:1-1:11:111111: bands111111115 of111' 2E". mm.111111.- :11'or !less1:55 alternating5111.15.1111111111 with51.11 111 broaderfut-11.11111 bands11511115 containing05111111111111; much1:11:11 hornblende.1'11-1.1111111111111115. 111In 1111111thin 511::section11 it11 is15 5151511seen “111111that 1.11::11green orientated5.1". 511.1111:11 hornblende11.-1.111111111511111: :11115'111LL11:5constitutes rather111111.511 more111.111: than1111111 111111haIf of111' such511:11 bands,111-11111.5:- the11: remainder1':111111:d:1 being11:111.:1 compased11111115111151.2111 of11f quartz,111111-1111.- plagioclasep15g111:'.115: (oligodlase)(11111111111115:} and111111- orthoolase,:1‘11111:1115.':. with1.511111 sphene5:11:11: the‘.‘.1: most111.1151- common::111r11:111 accessary.11::115'511151. TheT11: 11:11:11.5rocks 1111:5111:already 11111111111111.5111mentioned were55:11.5 11551151111111invaded by1:151 1:15111111111:felspathic 1.1511151veins 111111115111:alang the 5111111115=strike, 111.11and then111:11 cut:11: 1.11.1by twO'155111 111.111.:5dykes af111' intermediate11111211111151.1151: composition.:11111'1111115111'511111:The 115.1first cut:11'. the1.1.: banding1111111111151 af111' the11.1: 1.1-1.1.1.1 .11. 1.1.11...11.112.11.15 11.11 11".: 11151- 5““: host-rocks15.1151?1'1-1.1:k5 at11,: about1111515111. 45°,515 _ and1.11111 the111: 5::111111second was1.1:... 5.1.1.53]emplaced at right-angles to' the first. The minerals“31“‘1 ‘3‘51‘1 of511' both131.1111 dyke1111' 11: rocks15:55 are111151111551now arranged11111111111111 so511 that111111 the111.: dykes111.-1~'L:5 have11115-1: 11115the same511111: orienta-1111511111 tian af foliatian as the host-rocks, the earlier 1-‘1'11'55'dyke (34/71)(34.51“) now1111551 being11:11:15 a11. 11511111115111.111-hornblende- 1": 11111111111111 "5 111: “‘J“‘""C“'S1 "“13 1111111511 biotite-epidote1'1-1:111. gneiss and the later dyke a more1115:1111: leucocratic151.111.1111.”:11111: biotite11111111: gneiss311151155 (34/66).{351.5613}. ‘1153111E—1'1p1111111; 15115155: 111111 ““3 -“‘1“3f 1‘1"“: Pi Subsequent5511113511111.1:11.1. to11'-1 metamorphism111:1:111'1131'111115111 the11.1: whole55111111: complex:11111p11511 was55111.5 injected111j::1:11 55-11-11with anastomosing111111511111'155111; pegmatite51115111111111: veins.51151115- 12}(2) MIGMATITES1'1.-111151.5'1'1'1':5 In111 the11115 north-westernmutt-55:51:11 part[11111: :11'111:af the 11115111area the1111'.- 'BasementB11.111.111.1111 System71:15-51:51. rocks111:1:5 5111111151511exposed 11115-111have been111-1:11 higb!lyhighij.‘ 11111111.51'111'111t1.1'-:d.metasomatized. In111 hand-specimen11111111- 51111.111111111511 many11111111._"15'111L1111wauld pass1.11-1.55 for1111 15111111155.granites, 115as they1.11:}. are111': 111.:d1'111'1'1—medium- 1.11'or :1111151511111-1111111-coarse-grained, with1.1511111. granular511111111111 texture11.-15111115 and111111 often1.111.511 no111.1 fo'liation.1111111111111- In111. 1.1.1.1511expo- sures,5.11:5. 111155-':5-':1'.however, 1‘11:the variation5111111111111 111in :111'11111151'111111,composition, 111:the :.11151':11:.5existence 11fof 5:1'111:1':11schlieren 111'of contrasting:111111115111111 rock111:5; type,11.-151:. 111111and the1111: presence1111-5511:: :1.af higb!ly1111:1115 51111111111111'1contorted 1'1-1511111111:felspathic 5:111:551111115segregations 111111and veins5115.115 5111155show that1111.11: the111: rocks1'1-1:155 are11.1: mixed1111111511 1.111on .'1a macroscopic1115:1115:1'1111: scale.5::11-:1. TheyT111115 were1.5111111 11.151111:11mClJppedas155' migmatites,.L'111' 11111111111111155:- 11a raugh1:111:11 11115111111111.1111distinction being11:11151 made111111115 between1111155111111 11111.15:those :11111111'11111531containing 111111111[:1111:hornblende 1111111111among the1.11: ferro-1151111- magnesian11111511111511.1511 minerals,11.1111:111.15. 1.11111and 111115:those :11:|11515-'15151exclusively ‘.1111'11'11:.biotitic, thaugh1.1111111111111111:111:111111.'1:155-:1111Lthe junction between 1.11:the 15511-two types11:11.55. is15. gradational.111.11.111'111111... Some813111115 1.11of these“1111.15: rocks[11:11.5 ..L'1[:1.1.apparentlyL'1::1‘1111_5- became1151:1111“: sufficiently51.111111211111115 plastic1131151.: to'11'-1 flow.1115‘5' 10caJlly,'-.1.'1:5.]J.-'. producingp:1_11.111:11.11__1_ '.1a characteristiCailly1'1}. 11551151151155.1111. 5551111151swirled 11111.1and irregUlar111115-111111'111-.:1f111111151.1111151}111111115111.incipient secondary fOlliatian. These"1:115515 flow111111.51 51.111:1.'111'structures11.5 are11:'.' 1111115111often emphasized15111111111151.111d by115' elongated:11111g111151'1 1J)lebs‘11115115 and511:1 relic1:11.1151-111.11r..1disintegrating bands1111111215 :11'af felsic1'11-1151: material,1111.11:r111!_.11.1111and lines1111:5 of:11' 5121111schllieren1:11 ar:11'.1:11-1.11.'111L5remnants of111' the1.11: less11.::55. readily1'1 111.111. mobrlized11111111111111.1— members111-511111515 11fof 1‘11:the 1.111g11'111.11.511'11.1:1'1::.original sequence. (a){1.1) Biotite13111111: Migmatites.‘111'1'11111111'1'1'1111 A151 typicalL'.-111111111 511::1111-1511specimen 111af the111: 111151—host-rock111:1; af1.11 the111: biotite111' 15111.: 111.-migmatites'1.:111111111.5 {-'1—'1.(34/150)1.11.11 was51:115.. coHected:1'1'1‘1::1151'.' from1'.—.1151 11].:the tors1.3151. 13.11..one miIe111111: 1113111145151.north-west 111'af S1111g11'1'1-1Sanga'lo. TheI11: rock11111:: 1.5:is compact1131111115111. 111.11and 111:5:-grey, 111.111.1111:-medium- 511'.grained,L111:1'1- 1.11111and 1151111111111.without 5115111115visi'1Jle 1111111111111foliatian in111 the.1115 hand-specimen111111111 5111531111111 1111or in111 111111thin 51515111111.section. It is15 :5111'1111.1:1:1estimated 111.111that 11.it :11111111115contains 1:115 per11:1 ::111cent 111'of irregu!1arly11111511111111.1151 1115111151551disposed 1.11::11-1-11'1'155-11.green-brawn biotite'.1-11111.11: 11.5as 1.1115111smaill ragged 1:11.1511'511'5.crystals. The.The biotite111111111: 1111111511115appears in111 patchespat-1.111155 11551111151511associated 55:11.with 1.11grains11.3-11.5 0fof 51111111.:quartz and potash1111111111111 1151511111felspar and 1151::5511151accessory :111121111:epidote 111111and 5111151151.sphene, and-1111 11151.1also 11:occurs:1115 1:1in :1111:151111'111111115concentrations 1111111111111;outlining 1111:.the ,larger1111g:1 felspars.115151111115- T‘n:The main11111111. leucrocratic11511:: 1:1'1111: minerals1111111111115 are111: 111151.:quartz 1111111and untwinned1111.1.5111'1111511 -'.'1.1'or multiple-twinned1111111111115-1551111111111 1‘111513111'.felspar, 11.1111and a5 little1111|: plagioclase.91115111111115:- Specimen511::1111511 34/172,11.-"17"2- 111.111.".from one111—11.1 mile1111111 51111111151151.south-east 111of PireP11: 111111111151.market, 111511111515‘displays large.11. 1'1: 5111‘111111111]:1subpara'llel 51.111111111113115segregations of111 pink1111111:- 1:15p51felspar .111in aL'. biotitic1.1.5.1111... hast.1111.521- InI11 thin1.11111 section5151111111111it can:1111 beh: seen5::11 that11511. biotite11111111: constitutes1.111115111111155 ouly1:111 !5-' some511111: 3 per1.11:1 cent::111 orL11 4 per111.1 :15111cent 111'of the111: rock111:1: 1111111and is15 111'of a11 variety5:111:15! 111111:111:11:diochroic fram1111111 buff11.-111'! to'11'-1 almost111.111.5511 black.1.1.1.11.:11. It11. 11::1-11'1.occurs interstitia11111515111111.1111}:lily associated115.511:1111:1:1 with5511111 muscovite,11111531511111. irregular11.1:5111111 511111115grains of115' magnetite111111.111:111: 1111111and occasianail11::1151'1111111 apatite.11111111115. The'].'11: large1511115 felspars11515111115 111':are mainly11111111151 untwinned1111155-111111511 1.11or display1111511111151 very1.1511; shadowy511111111515. 155111111111:twinning 11111.1and have11111.1: 51111.11::|.sutured margins.111111511115. T1111They-' 111:11111:include muiltiple-twinned11111]11,r1]:-'155111111:1j plagioclase[1111;111:1115: within51511111111 the1.11111: 11.111151111111115:oligoclase range11mg: 11Eof :0111111151111111composition. Again. g1111‘1 the11:1: 5smaillerfi1ai]:1 12111-511115crysta:ls 5:11:1515'1consist {11‘of biotite;1115311115: inter-11111.11- locking11'1:k111g 1111115111155masaics af1:1t' 1111151111,quartz, 51.11111with shadowy5111111111515 11.151111131111111:extinction; microcline1111:1111:1111: and1111111 sodic511111: plagioc'lase.91115111121115: A.'5'11 111.1111.more homogeneous111'111111g:11:11115 111:1:rO'ck (31:19-11(34/193) 111111-1151poorly foliated{311111.511 111111and “"31““““31'111111'1111-medium-grained, formsF1111115 the'1‘.1.: host-rock111151—1'1'11'k in111 111:the biotite11111111.: migmatite1111g11111111: 1:115tors south512111111 'Of11f the1111: 5111511111Sorara hills,11115.5- It11 miles111.111..5 11.1111nO'rthth 1111'of |—1. Pire1’111': 1111111515:-market. Biotite11111111: is15 the111: 111111111only dark{111115 mineral,11111111111]. 11:1:1.occurring1'1'1111_1 in111 11115131111115aggregates-1_ that111.111. wrap551.511 round1111-11111 13 the1.11111 larger111m: felspars,1'.1111I1111'11. and1111111 111as a111 component11111111111011.1111 of111' the111.1. fine-grainedI111-.1-g1".111111'11 groundmass1'.1-1.1111111111111111. in.111 1.1111211which 111.1the latter lie.11.1. 1111.1The 12.111571:large 1131111911111felspars 111111.111.show 1111no 1111twinning,11111 111."_1.1— or1'1-1' 51121111111421'::111'111-111shadowymuItiple '.'-11.11111111141-twinning, "1113-11"while the11...1: fine-grained11=1...—-111.1.1:1.111.. ...'..1. material.1. ...-....-- is11.'. as.....-.1. in:.-11 the1'.--1.11: previous1".111 1.1.1.1 example..1..1111...1.1..-1- Specimen1111..1-_..1.-11..1--...:-- 34/192,.1-~'1" 11_..'11 from3—11.".:...111. .1.11.-the1 same1111111.: exposure.'.11'.1-.1.1-1-.11.‘ was,111.111. from1111.11 considerationIII-1!.- 11.111.11'11 .1113] 11of its11.11 field11:11.1 relationship,11.1.11111l111-1l1f1. assumed111111111111111 to1'.1 be1'11. part111112 of111 -' '.1a pre-metamorphism111'. 1111.1.1J.1111111rp11111111' dyke111. . 11.1.1 intrusion.1111.:'..... 111.1111.-'--. In111-. hand-specimen1....._'1..11.1111';1-:-.11:1':'.11.1.: it..1 appears....-1.111-111... _. . fine-grained.12..11.1 and 1.1....dark1I. I:.grey,.'1'1'. with1I.'.1 local1.1.".1'. .;-.._'1;1..'~1;-3'11__1---111:1;1-1concentrati<)lls 1'11of pink11:11.12. felspar.|.":.~II..1 '“ 1I11In thin11'1'1': section111.21....1:'1 it.1 1_.-.is seen1111.111. 1.1to 1.-._.1|11‘111.‘1-.consist' "' I _f' 1.1-1of1. the"'-'..11.‘n .‘1.1:‘11..'same1' --— mineral11I-11- Ir_'I11-"Il1. .LI 1.. ._i‘1-.'11--._.T:IL--|.'.1_'_.1..assemblage"."1"-1. ‘1'-1" 11 11‘1-"as' ‘the111'-.--"1 '4 1‘host-rock1'11.'.‘11-1'-._1-.'1'1 L1H;- but TtoL ll- l1..'..'.‘!2containI"':‘11.11:l. "' .J.'a 11'1.-.:.'1-|__1notably" "‘-"'J 1'1-'13 ‘1‘11'1-1higher.1231-1u:.‘I" proportion111'1'11'11111'11.11111 of1.11 biotite..11.-:1111111. InI11 addition1111111111111 small1111111111 131111112111113111111'111'concentrations '.'.Ilof I1'."11‘1iron 111':ore occur1'1-1.'.'-Ir '.11'11'1'1'1111111.11..1associated with accessory sphene. 1' -' . r ‘ ' : I" 11'1-11(b) HornblendeJI1'1'1."1F."1"}."11'1‘11'5'." migmatites1‘:1 .' “11" 1'1111'. 111' .' 1.""1' In.1 .‘.. the1.11.1 region11_-11.11111 of1'11 Kabiyet111111111111. and1111.1 immediately111' 11_-1.1211. 1.11to 1.11.-the north,111111111. the11:: 1'11:g_1111'..11:11-migmatite '.1'11111-1.1.'1.:host-rock is11 11.1-111seen to111 contain.11111 11.1. hornblende,111.111.11.- usually11.11.11.111".11.as -.11.~1I111.‘11-1.distinctive large11111.11 1-11.11.11.11.crystals. 1.11111-..I__1:11though the1.11. rock11.1.... is11 lighti."1_-'. in1.1 ._.I.:-..1L11cdlour .11and1.1 the..11; proportion11' ._11‘11.|f'[.|..|[1 of|._ _ hornblende1.1.1. .|:'.L1'L.--'._ rarely11:.1L 1'. exceeds1.1-...-.'..---. that1:11.21 of.'1 biotite.'111.'1.:-.1_'_ In1 . .1 ..-.___ ._.. -'-~.. .-1.-.-.-.- .--' .. .4: . ' . I.. .' 1. 1 1...... :...... this.11 1:. .1:-_.'..area, too,.1111. the1:11. concentration1..-11.II...1.1.1.I-.'.1 1.11of 11111171111.111.11'1131':amphibole-rich 11.5.1.1:211111131.111111.111'...11'.1."1..11segregations, disrupted bands .1..and.1 11.1.11part 11111.1:11u11digested remnants11111111111111. of.1.-.2 1m:the 1':11'1I_1.1'1'1:1'.'original rock."..1111' 111is 11:.rfar higher111111.11 than1111111 1111111113:among 1111.1the 11111111111biotite "1':1§;_-1.1'1':1-1I.11.11'1'.migmatites. 1",... .' ----. '1 "1 "1 .. -...... ' . 1. '1 . 1 ' . ""13 .' .... T1-I.'-.1...1T11.11Specimen .‘1-134/210-11.: from111.1111 1.11.".one .11-11.-and a.1 half71.1.1 miles.1111.11:~1111.-.1Isouth 1.11of Kipkarren1*-1I'1:1.... 1' T1 T1':I11'111-'."1market is:11 1.1-.1111-coarse- grained,13.711111113— with‘1’1'111‘1 no‘.11'1 foliation,1I.111111.I1_1.1. possessing111111.~.~.m_[ veins11.1111 and1.1.11.1 segregations11'.’_'-_I|'."'-..1-..11.11~ of'..I1 leucocratic1.11.11.31.11”. minerals,11111-111111- in particular1.1..1111.I..1.11. pink1"--‘--‘1 felspar,1..-111.11._... 1.11.1.andI isolated1:11.11.11--.-'. 1.. -..-1' black1.1.1.1.1-1.11_. .' amphibole.I...I1111-11.-.1:.1.."... crystals..1.... 711.:The'1 . dark'.1.1..-... _.: minerals--.-'.....11.1.1.1.11-. 1 11.1...are 1.11.11I-11.1..'.I.’1_.associated in:1-. dots,1..-1-11.11. and-1111.- I.1...|I11-.11.11.1consist 1‘.-1of biotite,111.111.13. I.1.-....I.1111.|J.diochroic from1111111 111.11.11-11..111'1‘1straw-yellow to11.I 1.1.1.1.dark brown;1111111111-'.—-1 . hornblende,11_-1‘1...I-1-111.11..1— 1.. ... plenchroicI.=1.131I-....I 11111.11._. from11.1.1'---.-1 pale1.1.111.1..-‘1 yellow-green_.:.111.11'..'-I—I'I:1_I1..11-.1. T-1_.1to.. 1.11.11dark_.I... 111.11.111-green;. magnetite._1.1g11.;_11-.1... _.' 111.1and. garnet.I..1-.;T1|L...- " :1" Biotite1.11 '11.. 111.1111-also'1--. 1I.....-11occurs---1 -..-|-'- .111.-as trainsI....11-.;.1-11.-. '|-- 11.of'I.‘1-I crystals.1-..'-1.-.11:1.-1—"'1r ----|.- surrounding:~1-_.1.-..1_1::I_1.1!£.'-.-~--1 ' 3-- some:~.I..-..11._'-..-1. - of111- i" the.‘.111'.;- larger.11..;:..1-.1-..1-- -.- felsic--.‘._~11-.'---1-1. crystals.1.131.111.1111. The1.11.1main111: 1111 light-coloured11.11—..1.1.1..--.11...1 mineral1111. .1..11 is.11 potash111.11.111.11. felspar,11 1.11.11either 1.111.111.completely.1-.._-. untwinned:111. 1'1'1111111 or1 r showing11-11111111; shadowy1111111111111. microoline.111...'1.:1'.'l111..- twinning.1.111111111.I-.1_ The1111. fine-grained11.1.-5_1.1111.11 material111.11.11.11 consists.1111111-1 of 1111111111..quartz, biotite.'1.-1.11111: 1.111.111and plagioclase111:131.1.:111~I111.3'11of composition1'11'1111111'_1111'.1-.':1:1 An3..‘11“. Specimen5.1.11.1.1:1.1. :11 .1—1'_'34/189..'"'._".1111 1.1.11.1from'.1.— -, three1.11.1.1.' .1. 11.111I--I.‘and .1_.a 1.1.1half1.11 miles11111.1.1-.-.: .- 11.111...east. _.of_' Kabiyet1x-."11_1..~1--'..' '. . .'-.is111 .1..a 111.1.1111....-11:1L1.I-.-11similar,-.'1---.-'.-—- though1. ,_ 121L111...darker 1.1.3.11HC'IJ_T.'..'11';_-._fcoarse-grained hornblende-bearing71111—71. 11.1 .11.-1'11..._:I_111_1I';_.[ rock..-._1...-.. In1.1 1.1.1:.thin '11'._’-._'1._:'._section it1:1L;:.LI§.appears 1-.1'-_1._‘._1;1;,:*1._1_sheared, with'111' streamed-out-11...-..1..-..-—.11.. .__1..1.'..1-.quartz 11mosaics..1.~11-.1.~.1 111.1and .‘.11.1..~.patches 1.11of ...... 111-biotite plates111111.11 .1and1.. 1.1.1.11deformed1.1- .1 111.11.11.11...microcline '1.!crystals.'11 (“1.1-111. (3) (1111.11111111111GRANITOID{-1111F.1.~111:F...~'1GNEISSES In111 1.11.1the 1'-c_1.11.'11:region 1'11of .‘1-1111.11.Soyet, 111111and 1111111111along 111.1the southern1511111113111 111:11111111111'}.-'boundary 1'11of 111.1the 11111111area west'11-.1111 of111' 111."the Kamaasae14111111111111 river,.1'1'11'1'11'. 11111.11much .'11'of 111.1the rock1111.1. .11.-111116.11exposed is111 ._'-1111‘111-1'1111131111111;quartz-felspathic 1411111111gneiss 111111111with '.1a _;T11111'I.'1f11granitoid 1.1.1.1111texture .'111.1and has11111 1.1.1.111been :'11.:=._1'.1-p11.imapped :11as 11111111111111]granitoid git-11111.gneiss. .11It is1:1 :‘11'11.not uniform1:..111"11117111 1'1'1'11-1'over 1.1111111.wide 1.11111...areas, 11111111-1.11'1§__1showing '1-.""1'F'E'h'ca variable 11111111111:degree 111'of 1'1-111111111111foliation '1-11'11'1and 1.1.1relic 11111111311banded 1111:1.'I.11r11111.structures, 11111.11and 1'.'1'11'11:.11-'11..11':_1_.-containing 1 . .1.-..:..patches11111 richer1'.'. 1.1in ...-1111.dark 1111.11.11.11.minerals. 1.It 1.1.1.1111grades progressively11-1..1._:1r.1.~111-..:._- into 1111.111:more 1111.11.11normal banded111.111.1111 .-.and1... 11.112.111biotite gneisses1111I-~.- to1.1 111.the ..1.east and north. The large.I.1_1-.-.. ..1I.1.11central -..11..1=1core of I.1111-.-...11.-11.111...1..1this outcrop, south .11of 1111111111.Soyet, is11 11111131111111.sufficiently 1.1:11111:'1_1_1.-1homogeneous1.111111; 111111and 11.1-11"1.11'.-1111j..-'sufficiently 1'.'.11111111-fain~ly 1111111111311foliated 11.1to _1I.1~11.11"j_1-'justify theI111: field1.L..'.. classificationL1.-.."1.“-1..11._.L.1l. 1. 1._|of "leucogranite",.LLJI...'-'_...1..1.1I.._- . though1:10.112.._ 1 the1.1-.1 .junction'._1:.-... |._.--1 with'1‘-...“ theL151- surrounding_‘1-_41'_.__|1_.__'._1;.;'_T rocksT1_1I._"r-1._‘- is.1-1 . . 1 . I . 1'.' 'Il'" 1"“.‘I-'.:1 r"- !1‘I ' r"1| 'Jl-I1 1hr - 1 ' - 1-1 1- 1- 1 1.."-'-.-1'-'-"'-.-1_...everywhere gradational_..-1.1.1..-_:'..1'.£-.11 ...111...and there.111. L is"1 no'11- indicationlL.J1-..111I II of'1 an1. intrusive.1 "1 '11.: origin.1'1 “:11: . .- .. .. 1 . . . 'I'...'1. '1'1'_ '1 -1--.---1 I 1 - ..- 1 ...- - 1 . I.. 11 14 r ' .. n. .-1. I. 1' . The[1"_1'1_' granitoid.'_III.'"".'.1.l.'1..-.1.__':' 1": I._'_'1-__'.“."1-1."\gneisses'T‘I 11"1' weather'1'-....‘1'..1'-.1‘ typically.'.1'.-....'1 to._'._.' form.-..I ._'1_ large1_'.;'_-_r._‘ boulders.__'._|._._1._.|:_' ‘11 1.1.1.that exfoliate-_‘-_...'_11__;1-;_‘ -_I; .- '.‘1‘l.' 1'11" 31:: .-.I-..- -- -,.-.III_-.II—.I -. '1' _._ '1'-"r..'-'1: "‘1' _. -.1— .. ...I_..... '.I . I ""1 ."'11"I. ..----. ._‘.I: _ with"-|-.| the.1.-.' J_-l|-"1--_-H-:..-_.-l..lproduction 1'11of 1.111.311.1131copious '1.-'1-1.'..."‘.-.'coarse-grained,.'_'1-.I..1.-..1... '1.-I"...1:|.:'-1.-__1quartz-rich .1..'rubble11_ which-1 ‘11-.11 '.‘1..'I'_.-1..1'.-supportsL51 little1...... vegetation. The 51111115gneiss 1'11.1:1..'1'.'._;----.outcrops :11'.are 1:11;cut -.;'-111only occasionally by quartz and pegmatite veins. in'.1'1 tbe111C 1111111111most homogeneous111.1:ll1".'-'—'UI1CI."'.!.1~' .‘1'I._"."'.'1-.‘-171-'1sections of1'11 1|".'.'.'the outcrop,I'.'|'.J1-.1'E'I."-:.'. but1.'-..1'. 1.1to 1.1."the north1"‘-1'1.'1 the1.'."1_ "“."':_T."=".111'.1'.'1--pegmatites1...... 1. .-.. 11 -....._...... I I -.-1 - ..1 -..-11-.-1--. .-. _.-. -I__.._.- I...... I-1. l”1‘.'-H1111.'. .' - I .1.l'I-.'I-..-1 '.'L. :L.-|-1.-|L.: -' II.- P --I1_ll1.-' I 1-... 1.- 1 " ' .1 _.".'..''1 :-. 1... ._."'1. J1 1.- '.'-111.. 11_"II -_ l' '1- _'_ become massive, frequently- - yielding— 'I- the only- exposures, and _providing heavy_ float deposits...:.'- I1..'.111'1111. --l-"11.'-." _ ---.'1 Specimens;."._I...1:11L.1:"‘I 34/308_'- _."-3'11"" andII!_1'I._| 34/316 from the top and bottom of the scarp south-east of'1 So'31 yet, both'.‘-1113.3 contain.'11111111r1 some111111.: 3011'1' per1.1.1.“ cent.".111. 111of -::111:11".:.--'quartz and:-.":.1 minor11111.11 1111111111111amounts 111.of mafic111:111. 11"11111‘1'... f.- 111 111: 1111111 111 111.1111... 11.1 [-..11111..1 111 1-11111.1.1.--.11.- 1.1-.11 1.1I111111111. 111.1 2.111-111 1111. minerals. I in , the . form. 1 of biotite, . part-altered. . to. muscovite and I epidote.. . The greater. part_. .l . --.- .-.-I . - -_ -- - - I- - 1 1. --| :5 -. -.- -. - - -. . . .- .. . . I _...... _.. . of-'1 11711the rocks1'1"...“111 is11 felspar,11-:111111. showing.‘11"11..‘-"-‘-2:1-_1_ perthitic_1 31.171111. intergrowth“"113 ._L1111'1‘11.11‘1.1and multipleI..11'..;11 1: or1.1. microdine1111.711- 1 1.‘ twinning.'.'-1.1111111“... -- - ... . 14 2. RocksHULL-3.111 Derivedflerh'ed 1111111from the Basement1111111111111“ System5111111111 (1)1'I_'1 MIGMATITIC11111111111111: 1'.}11.IL.1~LIL'1-.:~1GRANITES SeIL'L'I'uESeveral small1111'LLII :II'eL'11areas in11'. 1211.1the narth-west11111'1i'I-11'L'111 were'L1-'L11e mapped1111111111111 LL11as migmatitic11111111111111: gLLLL1i’1e11.ThL1granites. The justificatian1'.I1'-.11iL"L11iL111 farI'LJI' demarcatingLier1'LL11'L'LLLILIg themIhe111. from111.1111 the[he surraunding11111111111111i115r rock111L'IL types.11=11e11 is11 slight,111111111 and1111L1 1:1:111e1smaller expasuresexpLLLLII'LLL'L afL11 identicalELIL'I'L'LieLLi racksI'L1L'IL11 111.1111accur sparadically1111111L1L|1eL1II1L= LhI'L1LIghL1111through aut the1111: migmatites.:111g11111111e11. ']'|1L11'1They represent11111Le11L1111 Ihethe nearer-L.‘.nearest 111.1131L111L'happraach 111to' 'LI'LIL1true 1.11'L11'1i1e11granites developedLie1-'L1IL11.1L1LI 1.11in 11.1111situ 11-‘i‘1h111within the narthern11L11'1he1'11 part111111 (3|.-af theI:he LLrL1L1.area. 'I'I'IL11'They 1e1'11'e11e111represent metasamatic11e1L111L1111LLLie centresL'e1111'e11 L11111and the11111.1 prapar,tian11.111111111110111 1111''Of addedLLLILieLi 1111111113:granitic 111:11L'1'iLLlmaterial isiIL highest1'1ighe11'1 here,heI'L'. LLI1LIand the faliatian1'L1IILLIi11I1L mast11111111 irregulariI'1L'.-:;'.111|:-I.I' :111dand least11:1111 distinct.LIIIL'LjI1L'I. Inclusians[11L'11111i111111 L11.af :1111phihamphibale-richflle—1'ieh material11'1L11L11iLII areL111: still11111! camman.L'L1111111L111. The gI'L-LILLIL'FLgranites L-‘11L1are L'L1."I111:11:1campact felspathicI'L1|1~'|.1L11hiL' rocks1'L1L'IL1 :hL'Ltthat weather11'e111he1' 11112111111slawly, 11111.1and e1111111111e11expasures farm{111111 11111511.large ups,tanding111121111111111151 ma,sses,111111111e11. 1.11'af 1LILI'LiL'I1which ,thethe HLLI'L1I'LLSarora hills1111111 isi11 ane.L1I1LL'. A.51 11111110111II11':—1101'p111'1'IL1I1i'LL1'LILiL'micracline-parphyroblastic facies1'11L'1L11111L:is _.' LIL'1'LIIL111L1LIdevelaped lacally1110.111}. with11i111 the:11L:' felsparI'e11111111' crystals1211111111 up1111 111-to' 2_ ems.L'11111. lang.|L1I1g. .1.3. Nyanzian71113111111111 5}System11111111 ILL1L'ILILRacks L11af PrecambrianPI'L.'L'LLI'-1I1'.'i:1". LLLLL:age LL1L'1LLII'L'L-L'Liassumed :11to' hebe 1.11e2'11'1:11:hL1later than the H:111e111eBasement.1L S1-‘1'LIL11-LISystem 1111:are L'L111—can- tinedIiI1eLI :L'Lto' '-.E1LIthe 11L11.I:11—11L"1LLsauth-west par,t512111 L11'af Lhethe LLI'eLI.area. '111L1-'They cansistL'L1I11Li1.1 L11af metamarphased11.1111L11111L'1111hL.11'.L'-L1 LIIILIand LLI'LeLL'1LILLsheared 1115L':1111"L.'valcanic 1L1L'k'11.rocks, 111:111111mainly LII'af L1l'iLT1I'IL'III1:1:11111iii1'lariginal basaltic 1:11111L1L111111L111.campasitian, and by111' :LI1L11L1g1Ianalagy 111111with 1'L1L'1L11racks 111'af 11.131111111111111;neighbauring :11'L1L:111areas L111an 1hLthe sauthLLILL-LL‘I'andI1L1 west111.1111 are11:11.1 1'CiL'I'I'1.referredLI to'111 1:11as members1111111111 .1111 11:"af the Nyanzian'."~L1':LI11111111 System..1LjL-'1'L:L1.I.11. I +1 These'111L'1LLI PrecambrianP11L111L'1'. :L-z1 lavas'I-LI1'LL1: praduceI1I'L1L51'LL- a:1 number11.1L11111L11' afL11 small.11111L1:| 'OutcrapsL1IIIL".1.11111 but,hLI'L. excepteLILeL111'L where11'11e1'L' they:11L1jL' ocwrL1L:L:L11 iniI'L theI11L1 wen11e1| dissectedL1111L'eL'1eLI Nyandascarp,11'1L111L111 111:11111. expasuree111L111111'L1 is111 paar1111.1." and111111 the1111. junctians17111113119115 with1111111 theIhL' surraunding111111'11111111'11111 racks1'L1L'k11 LII'eare nat11:11 Lii.'1§|'_}i{‘1}'CLi-displayed. In111 theIhe regian11.11.111111'1 afL1I' Ihethe scarp1111:1111 it:1 can131111 be11L: seen11L1-L'1I1 that11111.11 theLIL-1.1 Nyanzian11111111111111 racks1111:1111 L111:are preserved1111.1.LI'LI1'LL'LI as:111 'I1lLt-L'k11blacks dawn-faultedLlL1'L1I1—1'L11111L111 by113. the1.11:: Nandi3.111111 andLLIld Nyanda1‘1}"L1:1d1'1 fault-systems11111114111111.1111; into111111 the1111:. Basement1311111.:111L1L11 System1111-1113111 gneissesgnei1111L11 and1111Li against1115111111: the1111.1 past-Kavirandian1111111-I1'LLL1'i1'L'11111i1111 granites,1__I:'LLL'1I'LLI1._ thaugh1111111311 it:1 seems1LL-1.11111 unlikely1.II1.I:ELL'-I'1.-' that111:1: the faultingI'L111hiL1LI. was11111. canfinedL'L111fiI1LILi to'111 past-MiacenepLIILL .‘1‘1111eer1e times,15:11:11. ILi11-L111when theL111: :L-L'Ii1'111'activity L111an II1ethe Nyando1111-1111111 fault1"L111]1 taak1-L1L1IL place.111L1eL1 As1.1 11]all boundaries11111111111111.1111 between111:1'11'L-1e11 311L:LIL1.1LIL.ILNyanzian racks."LI.L:'1L'11 andL11111' BasementHLIHL'I'LLen‘L System511111111111 gneisses1.1L111i111e11 abservedL111111111'eL1 areL1Le faulted,1'LLLIJLL'Li. in111 the1111.1 absenceL1111'LL111'L'L1 'OfL15 atherL1111L1I' evidenceL':1iL.-L11'1.L'L1 the111-.1 remaining1'e1111111111'Lg:i11L1.lines betweenhe 111'L1L'11 rocksaf1'L1L:1L:1L' 111 these111L11LL1 types1'LL-111.111 shauld111-:1LIILI alsO'1111111 be1'.-L1 tentatively1L'I11L11i1IL.1!1 cansidered-LI"L1.~iLIL'."L:LI LL11as 1.1111111.faults. _.i'1LL1L1111L'ILTraverses in11'1 theIhe Sauth51111:."1 NandiI'LLLI1LIi Farest[7111'11111'revealedL"1'-L"..-“ed .1111:streams:11-.11: crossingL'1'L11111111g cauntryL'1'.11111-' 1'1 campased1':L1111111'.1:-'LL1Li mainly1211:1111 111af L'L1L11'11L-111L1111Lcaarse-grained11 granite,1.11"L11'LiLeL with11: 111 locally,[111."1.|I'1'. hawever,1.1.IL111'L.11' 1..r 1LL1L11flaat with11-‘111'1 a:1 1111111high percentageI‘ereenluqe af1.1' NyanzianT11:11111:i:111 rockI'L'IL'IL types.11=11L1L Invariably1111;114:1111 1:.1L=_L'1:.11'L=LII':L':.~'L11131::exposures were So'1111 1111.1.1111L1sparse :11.as to'11.1 render1L11'LLIL-1' 1.51.1.-delineatiani11e11111111 111'af the111-L1 autcrapL11:I-L"L'L'.LE1 baundariesI111LII1L1111'iL11 impassible.iL'I'L:.1L11-..1:i':1§e. It11 is111 considered1:11:11'LiLieL'eLl probable111111111111: that'-L]1I'ILI such.I_I1LEL_‘L"1 blocks:1IL:1L';]L'~L'_ ofL111 Nyanzian7101;111:1111 rocks1'L1L"IL1L existL:.1Li1'11 in111. the1111.1 graniteLLTLLLIIILe :11;as xenalithic11311111111111; rafts1:11111 arL11' raaf111111 pendants.11111113111111. TheT11L- degreeLiter-1.1L- L11"af metamarphismL11L'I'.LI1'1-.11'11|1i.1111.. LIZ'af theLILLI 'lavas1111:111 increasesL.'1L'I'eL11LeIL pragressively111111.111.111111'_1. to'111111:the narth-west,11111111 1113.11 the'-.|1-L'.' racks1'L1L'1L11 in:11 the[he south1111111.1 retaining1L11L1111111g unmistakable11:11 I: i111L11~LL11L1|e basaltic11.:11111]Ii1.: characteristicLILLIILLLLLIIILIIL while1111: IL1 111L111Lthase in1:1 the[:11-L narth:11LI:".11 resemble1'LIILLII1L111IL: more111L11'L1 closelyL'iL111L1:1' plagiaclase1111151111.: LL1'LL' amphibolites,:11'11L1L1ii1L1Ji1L'11. petrologically11e11'L1IL1gieL111‘L1-' comparable1:1111111111'11h.e with1.1.11.1 thase111-L111: in1'1 the111.: BasementI'1L11Le11111111 System.111'1'LLL1111. SL1:I'LL1Same L11"af the1'-.'1L.1 H1-‘L-1111LLIL11'.Nyanzian rocks.I'L1L':IL1L still12.1111 LIi1LL1|L11=display :1a campact,L'L111LI.I‘I:LL'I. I111fine-grained1—I11L1111e11 111-'L-11111LE'11L'.basaltic L-1_1._1.11.1eL111Lappear- anceLL'I-L'L1 in 11:11111—1111L'L'i111hand-specimen.L111. F111SpecimensL1L'i'1'LL'L1I111 34:5234/52 L'LI'ILIand 34/54.1-1 :11 1111111from the1111: 11L111h—L'11111L'IL1north-eastern 1LL111L'11slapes L.-of Koyo1~LL11'11 hi]!hill 111111and 714,-".1111134/396 LI.1.LIand ."1—‘134/398,31.11111. 1111111framone11:1L': I11iIemile 11'e51west .'.I.I1LIand 1111.111three LLIiIL111miles 11.111'111—11-‘Le111narth-west ofLII' K.LL}1ILIL11L1Kaptuma I'eipL'L'iI1-LII1.respectively, :11'L'are L11'af 1111.1this type.11-‘11L'. 'iThehe firstIiI'1LI 1111.1.twO', thO'IhL.111g_hugh 111.111"naw LL111111L111L111camposed mainly11111::111 afL1: 111111131IL-11LIL-harnblende preserve1111;111:111: L1a relic1'L-IIL' igneausigI1LL'L111111"L:-1'LL11'1111'-.feature in 'LL'1L:the lath-shapedLLIIh-1i1:1_11eL1 patches[111-$111111 afL11 recrystallized1eL'2'1'1L'LLLIIE'L'eL felspar1'L111L211111 1-'i1'~:IL1Levisible 111in 1111111thin 11ee11L111sectian and.and 111in 2111-111134/54 er1'LLLL-I'I11crystals L11'af the1I1LL1 L'IL'igEnLLIariginal 11111111211111igneous pILLgiL1LIL11LL:plagiaclase remain..i-L'L11LI1Li1'1. H11eL:1111L111_1—‘r_.’1'11'1Specimen 34/396 h.'111has 1LLII~LLLIIILLLLJrecrystallized to':11 a plagiaclasepILIgiL1eL'L-11'LL: L'111111hiL1L1211-L-1amphibalite 111111with 51}50 "perper L'eL'L'Lcent hL1I'11111L111LIL'harnblende, L111111'L111L'I'1111LI;appraachingeuhedrale11heL11'L1L‘ 111in LhLIpe.shape, L'LIandI1Li e1e:1.-"clear 1.1'LIL11111'.quartz L-11111and 1'ei'1111111felspar,1L ”thethe latter1:111L'1' 11hL111-111I1showing 1111111i11lemultiple 111111111113twinning. T11L11L1Mare caarse,lyL'11a111eI1I {:11-11111crystalline11111.1e 1'LL-1.1111:veins 1.1111111111111111camposed 1IILLIII1I11'mainly L11of 1.11::11'11'quartz 111111and e11iLII1IL1epidote 1:111cut :hethe rock,L'LJek,'L§1ethe ILLL’LL'L'latter 11.1111e1'111mineral 'LLL'FL'LIalsa L1e'L'LLI'1111L;accurring 111in L111:1L1eiLL'11L11111-'i1|1associatian with harnblende.11111'11IIL1-11LILI 111111and paikilitic1111111. 111: platesI1|111L111 L11“af LILL111LL'iLIiL'di'Opsidic pyr'Oxene.11.111.111.311; Specimen 343111334/398 11’—1111111shaws 111in 111111thin 11.11.111.111sectian aLL ILL-L111well preserved1111111111111 13111111111igneaus 1e111111e-texture. "1111:The 11115111111!original pyroxene111-'1L111e11e- 111is ELLL'LIe:_-'largely 1111111311altered to' 11111'11111e1111e.harnblende, 111111and 11eL'1111-L1I111.accasional biatite,11111111111. but11:11 11112111.there L11'eare remnants1'LL-111111111111 af1111" felspar1111111111 prisims[3111111111 up1111.- t'O1L1 -!1 :11111.mm. in length.[1.1113111 -- -.--.-- _I 15"..-i"| ManyPi-ltitiy L'it'of thetlte NyanzianNyanainti rtieksrocks are highly shearer]sheared aritland the:'L e mineralstiiitterals tlispiaydisplay etiiipletecomplete recrystallizationt'eei'rstalliaatiett and a pronauncedprt'iiititttieetl preferred 'Orientation.Lirietitatirin. The rocksrt'ielts are Liftetioften bandedhatitied :ina‘and frequently inieeietlinjected 55'i'liwith tittartitquartz ortir graniticgranitie material,niateriai. :ttitland ironirett pyritep5'rite is etiaitti-Lincommon tiltingalong .trat'ttit'efmcture planes. S1eeltt'L-ettSpecimen 34.5351134/342, fromtrnrtt tirieone 111511and :1a hallhalf triimileses !south-west5L1111h—555est tit"of Kaptumo,Hapttttiiti. is variably5-'arial.il5-' iit_ieLinjectede11 55111‘1with granitiegranitic 'i'Laterial.material, locally1ee11115' epidntiaedepidotized and richt'ieh iniii pyrite.15-5'r11e. SpecimenEirieeittten 34/403.1515 5111.1 fromtreat the mosttittist. northerlyiiLirtherliLr outcroptititt'rtip 'Oftil.‘ Nyanzian5551111111515 volcanic5'eleatiie rocks,reeits. oneLine LtI1L1and a halfhall 111111.55miles northnt'it'th 11fof Chetttegnnja.Chemogonja, is anotherattt‘ither fracturedt'raL'tttreL1 banded1511:511etl rock.rtieit. In1n thinthiti set-Linnsection it is iitjitil'lt'ifound totti behe well t'Li-tiatetlfoliated with551115 handsbands :51of hernhlendehornblende attL1and plagioclaseptagieelase grading intoitt'LLi bandshattLls etittsiatirigc'Onsisting 'OfLit" atttt'iaritabundant grattttlesgranules ofLil diopsideLlitipsitie set in large poikilitic15111151111111: platestiiares oftit' L:5.i.ieraeiisite.clinozoisite. FL'nialiSma!Ugt'ai:i5grains ofLit' .5pl5enesphene are present antiand the it'titiiron tireare is1.5 pyrite. Half a miletiiile jitrtherfurther southsetith the reekrock eapesedexposed is agaittagain a.a haittletlbanded plagioclaseplaginelase L1amphibolite.tiphtlitilttL SpeeittienSpecimen 34/135151.535."? l'rtiriifrom this localityltieality shtiwsshows tieeasitihaloccasional lettetiertitieleucocratic and ttlttphihelitieamphibolitic hanels.bands, the rockreel»; 115as a 55htilewhale consistingetitisistittg 111'of 111160 per eetttcent hornblende,htirtthl' pleochroic from buffhalt into dark greengreen, plagioclaseptagii-LiL-l:i-se titof L'tcompositioninititisitinn L511An 54' setttscatteredtet'eel et'5'sta15crystals antiand eeneetitrat,concentrationsititis 111:of grains oftit" t'iit'ipsitle.diopside, and tieeasitirtaloccasional Littat'tIquartz lenses. lilirarittlesGranules Lil.of sphene are 111151115t1151"abundant and samesome magnetitegeett e is present. The rockrank is netcut 155'by eh1riritechlorite 5'eitttetsveinlets ata,t right-anglesi'igh15atig1e5 totn the 1‘Liliatitin.foliati'On. Occurring1.}L'ettt'1'it1g 11111amongt5ttgtt'tr1remore typicalL5 ptLLtl NyanzianHyattziatt heatfloat in severalse5et'al oftil‘the SouthEtitith Nandi1‘5arttli Forest[tirest sti'et-Lntsstreams are highlyhtghliL' shearedsltearetl ttt‘ltiand fracturedt'taettit'ed stlieeetissiliceous rocks.reeks. Thin sections5LLLLLLL5 providept'L-L-'5'Litle little11111e e5-1L1L515L'eevidence 115as toin their tiriginorigin 11.5as they111L555 5.111155show 'Onlyti1'i15'11a variety5'ar iet5-' 11Leatae1astieof cataclastic textures,textures. involving1115-51515111g leucO'craticLL-LLLLLLLLttLL ttiirierais.minerals, moremere 111‘or less115.55 disguisedLlisgtiiseti byh}: the introductioniitttLititietitirt titof titltjtll'ltittf'y'secondary siliett.silica. Suchhaeh rocksr-L'ieiLs maytin-.155 betie producedprtititzeetl froml.'rtini highly shearettsheared Basement SystemSjL'steni rocksreeks atetigalong the fault-zones111111 1—series boundingtitiatitiing thethe. NyanzianHyanaian outcrops,ntttert'ips. or151' maynit-15' represent silieetitissiliceous members of111' the:h.. NyanzianT55-L55.ti111an 55:5volcanic5111' ie suite.sttite- {JitterOther materialniateritLt originatingerigittating fromt'reini t'attlt—aenesfault-zones appears ttito consistL55: 5151 t'tlii'tistettiire15L'L51‘almost entirely of hightt-highly 11'15'11'111111Ltetl'mylonitized quartz,1111.111. Littenoften Lil'Ofmorenitire than Line.one geiiergenerationratititi 5151.1.and richriL'h in115 ironii'Liri pyrite.p5-r11e..55t1An ironirtitt oretire L'i1tteeL'5‘trtttin15._i—1_.'concentration (34/341)3—11. associated11.51515eiL-11e11 with55ith the Nyanzian1515' 5115151:1:5. ...._ rocks."ti'L'15'.:5 two15511 miles15511555 northitetth L11of KaptumoconsistsKaprtiniti eLirisists of1.11 a highhi-g.'i proportianprLir'Lirtiett ofLit limonite.111ttertite. The"1 he texturete5L111re ofL111 inelr1L1e5L1included fragments1rr.'.1gt't'.eri15' sttgge5tssuggests that the rock151t was55115 tiriginal|55originally tia brecciahreeeiti L51of granulargrtstitttat' fine-grainedi'ine5gt':.Lit'-.eL1 material,tiiLtterial. consistingeensisting ofLii' .51rainee'strained plagioclaseptagiet.'LL-15e.attt1and quartz,tittarta. the fragments1.1... LL115 beingneitig roundedt't5t1ttLiL5L-Ll and11151.1 reso'rbedt'estirheti at thetlte time'Lirite 'Of111‘ replacementrep‘5LLIi5'tL by115' secondary15Let11LL1 IJmonite.-'.‘.'|.'|L'i"111'§'L 4.51. IntrusionsEntmsiens intointn the PrecambrianFreeatiihriaii RocksEtieits rli(1) MAJOR51.511111 811.1115SILICA-RICHHtt'it INTRUSIONS1511115511155 (a)[11111115The Maragoli.-'1L'1'LL'i'L'L'_5L5ri.-“E 1515111511:granite Inin the e.L5trextreme'“1'11e stittti—tsouth-west55511.51 part L'ifof the areaarea the eL'itiL'ttt'5'country rtiL'.1Lrock 15IS L51of D55rat511e.granite, 1:11""'iand“5. 5...a -L';L'ie15'variety Litof siti'iiiarsimilar eLiarse—coarse-grainedgrained reeitrock 15511.55types hai'ehave been itittppetimapped as a single unitunit, :‘tt-Litighthough they probablyprehahiy represent.represent the restt‘Ltsresults titof rntiremore than tiieone ititt'11515-'eintrusive phase. No15 -.i eerttaetscontacts between Ltissimiiardissimilar types were reL'tigitiLteLtrecognized in the tiettlLfield, 1.5111but 11a 111511uniformLit'i'tt att'Lland Lii5titteti5'edistinctive [ii111-Lpink perph5-'ritieporphyritic faciestaL'iea exists e5-'e1'5_L-'55-'he1'eeverywhere 555'estwest and mathsouth L11of the K115Koyoiihhill1 15515-Nyanzian11151111115 LiL11L'rtipioutcrop altingalong the mp5top 111"of Lthee 1'55'1115Lit15eatt1.Nyando scarp. This granite is etittsztieLconsidered"' toihebe the thatmarginalgittai at'itiezone etof that mappedntappetl ere:over wide areas 111to the west.west, 55'11erwheree Pulfrey151111 11515115.(1946, p.15. 21121) reeeigttizet'lrecognized the 15115511511115possibility tilof morerritire than tineone iiitrintrusion15itirl 1tirtttittgforming the granite initt the Mat'agetiMaragoli area. The gt'att:1iegranitic reieitsrocks titof this part L11of Kent-'11Kenya eahihitexhibit with:wide 5'triatitirisvariations in appearaneeappearance artandti composition.et1ttipt55itii1it. In the area south51511115 151'of the present area leucocraticlettetieratie granites haveha'L'e beenheeti mappedttiL-Lppetl (Binge,13111n 1962),1111125. andanti granitegranite, ptit'p'ttyritieporphyritic granite andat'.L' syenites5'e.1ite totei thetite .5L11111'L-55'e51south-west [tittggerstitt(Saggerson, 1952,15152. p. iii—'1164) while tilof the granites immediatelyirnrnetiiat'eli' tnto the wetwest Htitttilesttir:Huddleston (1954,115.55 p. 16)1111 remarked"reniari-teti . .. .. relati5'el5relatively-' large titassesmasses titof hybridh-L'hrid 55'ertites.syenites, ditiritesdiorites antiand 55Lsyeno-dioritesen-Li dinrites have heertbeen pt't'itttteeel.produced, pessiti15'possibly 115'by the eittt'etiieextreme atteratieitalteration etof roofl'DUi: pendants LitofJ earlier intrttsi5'eintrusive tit'or 551111—rtieits'wall-rocks". I 16111 Owing0111n to‘111 theLhe. nature111111.11e 111:of theihe terrain1er111111 in111 the1he Kapsabet15.111111111111131 area,111‘13 . 1hethe high1111111 dee1‘eedegree-1_- 1.17.of .. granitization11111111111111111111 of111 the[he BasementBE15e111e1'11 SystemF11'111e111 and111111 the development11e1I‘e11‘1111‘11e111 111'of a11. 1111111111.distinct foliation11'111211111111 in.11 1hethe 1311111111311granites in111 1hethe regionregien 11:1of 1he11'their e111111111.contact, 1111:the delineation1111111e111:'1'111 111'of 1111111their 111111111111boundary11'111 is:1 difficult11111111111 and111111 must111'1111 be111-1e11111111e1e11considered approximate1111111‘1'1111'111ete 1111111:only. The g1111111egranite 1.1111111south 11‘-.3of 71111111111Ndurio 11111111311.weathers 11111111111along 1:1‘111‘1'1111er11prominent 111111111joints 1111-11and isI.I. 13111-11111typically.13.” exposed'.':2'111111-‘1111 1111as 111111tors 1111111and massive11111111111'11111111111111monolithic.11: blocks1111111111 111'of 11a bright11111111.1 'I 'I pink11111111I colour.1.111I.1L11.h1':1s1:ee1111e11.-'11.-- I...- In1'. 1 specimen . i'l 34/394_..'.1".I.I'—1 from1'1‘11111 this111111 111-111.part, 111111pink felspar1111111111: phe1111e1‘1-1I1111phenocrysts 111111111111“display prominent‘1‘1:‘1‘1111111e111 e111:carls bad twinning11111 11 . - and1.11111 1111111111stand out11111 from11111111 1hethe 1'1-'e111he1'e11weathered surfaces,1111'fe1ee11. 111111and quartz11111111: 11111and_n'_ biotite1111111111. 111111can be1: 1111""11I1.11recognized in111 '11a 1'1-.'1111111'111'11yellowish 1"e111‘11‘11h1efelspathic groundmass.I.I:111111111111111‘1I'1. In[11 111111thin :I'.e1.:1111'.1section 'large1111'11e1111-111Ie1111e11microclines 1111'are .I1ee1‘1seen 111to hebe 1-1I'1I11.1.'1111-.11associated '1'-1111with 1111:1111oligoclase,e11111e. 111of 1.1-1111:11which 1111311they 1111111also 11111111einclude 111.11:111.1:111-'11111'111.small crystals. PlagioclaseP11 5111111111: crystals111111. 11111111form 111111111about 11a 12111111third 111'of the 111e11.rock, with1.1-1111 1.1113111:quartz 1111111111occurring 1111as large11': e 11.1111e11'1‘11'1anhedral platesl-I—|I 11111e11 111111and 111111-111small 111111111111mosaic patches.111111111111. 'Thehe 111—1111'only 1111111dark 11111111111111minerals presentI11‘e51e111 1I.:‘eare biotite11111111e 11‘1-111and :11'1‘1'1111small 11111111111111amounts of11I e11111111e.epidote. A.51 similar1111111111 rock11:11:11 (34/399)1.1—”1.:'.111111'1'] from1111111 five11'1e miles11'I11e11 south-west11111111'1II1I11'1'11 of11: Kapsabet1111111111. e1 containse11-'I111111.I1' smaller111111.111 pink carlsbad-twinnede111111111111-1I1I11111e11 felspars,1e1111111‘11. and111111 considerablee111111111e1'1'111e epidote111111111e and"1111 pyrite. Ragged111111.151Ie11 plates11:: of1111' highly111111111; pleochroic[11e11eh1‘1'11e biotiteble11‘1e constitutee11111‘1111111e someI.I-1111111. 51 per1111‘ cent1.'e111 of111' the rock,reek. whileI.I.h1'1e patches11111e11e1 of111' clear1.:'1e111‘ interlocking1111:1‘111ek111g crystalse1'11'111'11'111 of1'11 quartz1111111111-11-1‘e1111111account for1111‘ a'-.I. further1.'111‘1he1‘ 151:1 per cent.1e11:. The remainder11311111111111. of111' the rock11'1e1-1 1'1.is composede11111p111'e11 of felspar, the11'1e plagioclase1111:1111 11e.:I being".._'._-'_.- I1 highly 1111111'1'11'111111sericitised and111111 displaying111111111111'i1‘1g shadowy.I1h111.11I.I.'I.-'111-1111111111.twinning suggesting111:1.CI'1I11 11g a11 composition1.1111111111111111 of1'11 An3o,.I"I111 An15111 e111:‘e]11e111-'extremely leucocratic"..1I.1e1.1'.':‘111ie facies1'111'ie11 1.1—1'3'111'1(34/395) from1111111 within111111111 theIhe forest['111e.=..1 1111111111111consists 1'-i'of 40111 per eeI11cent quartz,1111111111. the111'1 rest1‘e.:: being11.311111 mainly11111111111 felspar.1e.II1|111|‘. Accessory.'15'11111e11.I1111"-' 111.13.1111'11-1111quantities of111' epidote.e31111111e. muscovite1:111:1e11'1'1'1e and111111 chloriteeh]111i1e almost11111111111 replace1e1111111e the1111' rare“are biotite1111111111 flakes.fi11ke1‘1. The felsparfe1r11111i‘ is151‘ mainly11111111151” 1.'-:3 slightly11111111111'111'11I1'e1.II" altered plagioclase,111I1II11I1.]11I1 1111so the1he rock11111111 is[.I1 classifiede11'_'1111'1e11 as1111 a'11 leucocraticlee-131111111111: granodiorite.E1111I The granite in111 the reg-1111regi-on 111'of ChemogonjaL'he11111g11r1j11 [31—11114](34/64) 11111:has 1'1a distinct111111111e1 foliated11111111e11 11111111111.appearance,‘I 11-11'e. with111111 large11115.;e pink1111111 phenocrystse11en11e11111111 wrapped1111111111111 in211 11a fine-grained1'1111:~_I.,I1'1'1111e11 1111111111matrix rich1'1eh in'11 1e111..1111w111.1111111ferromagnesian minerails.:111'11e111111. In111 thin111111 hiieeslice it11 proves111'1111-e11' to111 be111.”: highly11.: 111111: Iihe111‘e11sheared 1.111111with 1'111.I:1e1‘I1clusters 111'of 111111111mafic minerals,111311e1‘1111. composed11111111111111.1311 111of biotite,1111111113. epidote,e1111111‘1e. sphene111111e1111:11111and occasional11111111111111111'1 chlorite,e1121'11'11e. streamed-outI111e11r1'1e11-1'I111 around11111111111 fractured1'1'11e1111'e11 felspars111111111111 111111and 1111'3111e11strained quartz.111111111: {1711111111151Crossing [hethe 11‘1he1‘1I1-111eotherwise uniformL11111'111'11'1 1111111111:granite exposurese.'I11111:I111.-'e11 111111111south 111'of Ndurio111111111111 is[:1 11a broad11.—111111 1111-..‘1tract rich:‘1eh in111 xenoliths.11e1111111h11. The host-rockh1'1.I1'1— 1111111 is11. the1111: typical15111111 highlyhigh]; porphyritic11I111-11hI.-'r:'11'1.' granite1111111111: of1111' the'111e region,1'e1111I11. while'11-'11'21e the111e included111e1111‘fe11 f1‘11g1111e1111'1.fragments, often111'1e11 1.11so 1111111111111'11abundant as111-1 to111 form1111111 two-thirds111-1111151111 of111 the rock1111111 mass,111111111. 11111are highly1111111131 altered,11l1e1e11. 111111and 1111-111may originally11111111111111 have1111-1 been11ee11. 1111e11e1'111.of leucocratic-gneissic'1111e- 1I__'.1I:1I'..I1I'1.' compo-e1I111111‘1- sition.I.i1'f1'-11. The trend 111'of lhethe 1111111111115111111311contaminated tract11111.". is11 111111111about —'.1'.I'_40°, I.I.I1-'.1and theI111: fragments!1‘:1_I_.I11'1e1‘11..I: 1".1'1'are elongated1'11111gz11e11 in111 that111111 direction.1111ee1i1111. (b)'.'.".I'I.-"I.-'r'1I1‘.I11'.I1'1‘.I1.I._I.‘-I.'1'.I11"1I1'.-.I'1'.'I1‘.'.I'1'Northern granodiorite South-west13.1111111—11-‘e1‘11 11]"of l{C'1‘1e1111111I1I11."1Chemnowet market111111111-‘1 11a coarse-grained1'11111‘11e-111111111'11 rock1111111 of111' igneous[1111e1111I1 e111pe11.‘111‘1eeappearance occurs,1'Ie'1'111I1. contrastinge111111'111'11111e markedly111111'11e111'1' with'11-1111 the‘111e surrounding11111‘1'11111111111; rocks.11111111.. The rock1111111 is11‘. without111211111111 pronounced11.111111111111111 foliation,1111' 11.111311 and11111 the ferromagnesian1e1‘1'1'111111ghe11'11111 minerals111111e1'1-11I occur1111e111' in111 clusters.111111111111. It11 weathers11'e1111111' readily1111111111: and111111 exposurese1111111111e11 areere confined1:1.1111'i'11e1'1 to1111 the111e streams.1111;111:1111—1111The rock1111.". was11.-11:1 mapped1111111111311 as11:11 a hornblende-biotite1'1111'11h1e1111e—11i1‘1111e :11granodiorite,1111111.: 11.—111.1. intrusive11111111111'e into111111 the1111-I: Basement1-5'11I1e11'1e111 System.$151e111. CrystalCry-11111! size varies1'1-1111111 within1.1111111- the11111 outcrop,111111111111. 11.-1121111111specimen '11-111134/194 beingheing 1'1a relatively1e11111'1-'e'_I_.' 1121111—fine- grained-_-"11's1'1e11 sample.1111111111e. In111 thin111111 I1ee11'1111section iti1 is31. 11ee11seen toI.1'.- consist1'-'.'1.I1.I1'E;'~.1 1'1-‘1'of 1111111111.some 81'I' per111:1 centee111 dark1111111 minerals111111111111 with111111 :1a preponderance111'e11e1111e'1'11111'e of111 subhedralI111h1e'..1 hornblende11111‘1111.-1'I111. over111-e." more11111111 fine-grained['111.I.I-I:I."11:'I11:-'.1 biotite.111111111. The former5111111111 is111 pleochroic1‘11e11e111‘11'1e from1111111 1111.211light 111?yellow-green11.11111——__-_'-.Iee111 1111to 11111.11dark green.green, the latter111L1e1‘ 1.11111111111'dichroic from1'11111'1 straw-yellowI:11‘11"1I.‘I1'—'1-'e'=|1I.I1I1' to111 dark111-1111 brown.111111-111. Quartz,l1.111.111.1111. 1.11111111111111-constituting some1.111111: 21120 per11131 ee111cent of1.11: the1111-: rock,11111.11". occurs11:1:111'1 in€11 1111‘11e11'11e11.large clear1‘ patches,11111111111111. 11111I11often e.111'.1."11e1'1cracked 1111111-"'111I111'I:111'1:'I1'and occasionally .I1'1'1-"11I1I1.'11_I_Ishowing lines1:111:11 11"1'11of dusty1'111'1I 111.:‘11111111111inclusions and1:111 shadowy111111111I.I1-'I_.-' extinction.11.111111111111111. The larger1111'g1121' felspars1111111111. 11111111.;consist of111' orthoclase,1.111111111111112 often111111111 rounded11'-111111111 111111and resorbed,1‘e.I:1'.1:"'11e1l. and111111 plagioclase111:-1g'111e11111e of111' 11111Iee111111Ioligoclase composition.e11111111111111'e11. The 1111e1—g1'11'5111111finer-grained material1111111111111 consistse1.1111I'E.I11.I.~ largely11111IeII.-' 111'of 111111111111similar 1113;111:1151?plagioclase 1'13'felspar,1.1111111. 111111and 1112::115111‘1e1accessories 11.1111e11noted included1111:11111e11 1111111111zircon and31111 calcite.e111e1‘1e. ~ 17 (c)tel Southern granodioriteg-‘eriirnr'iort'te Inin the south ot'of the area and well esposedexposed along the SavaniHay-am road donedown the.the escarpment to h-tuhuronhMuhuroni, there is an intrusion likelilte that of the northern granodiorite into the Precambrian granites and gneisses of that part of the area. Specimen 34-30534/305 is a coarse—grained,coarse-grained, biacitblack and white rock, of igneous appearance.appearance, without pronounced foliation, and carrying biotite and hornblende crystaiscrystals up to 1 cm. in length. The hornblende.hornbJende, pleochroic from dark to light green occurs in coualequal ttn'tttamountInt yyithwith biotite,hiotite. dichroic from yeilou.‘yellow to dark green-brown. Sphene occurs associated with iron ore and hornblende,hornblende. and is also present in large euhedraletthedral crystals. QuartzQLIHT‘TF constitutes some 15 per cent of the rock as irregular patches of interlocking grains. and small areas of quartz-felsparouartr—t'elspar intergrowthintergresrth are present. HomeSome of the felsparfeispar isIs slightly sericitized,scrieitiaecl. mostroost ot'of the rocltrock hctngbeing composed of plagioclase,plagioclasc. some ssiti‘twith subhct‘lralsubhedral form and fainttaint. stoning.zoning. The catinctionextinction angles measured on the multiplemu.tiplc twins in the better preseryed crystals indicate a composition syititin the. oligoclase range. ___—._ twins in the better preserved crysta!ls indicate a composition within the oligoclase range. __ Microcline.‘slicrociine occurs interstitially and replacing piagioclase.plagioclase. (2)tilt BASICRitstr INTRUSIONS[statjstoss titlHtghty(a) Highly inereinirirpr’toseitmetamorphosed orrsir'basic .-ri.-‘.r'.=t.~.t"-.'eintrusive rot-itsrocks--PlagioclasePreterm.nurse Amphibolites.-t.-i.-t'tr'r.'.’lo.-'.-.-'i-s PlagioclasePiagioclase amphibolites are not common in the area.area, but occur among the migmatitesmtgmatitcs in the northwest.north-west, where they formterm a contrast with the surrounding leucocratic rocks.roc'as. Where1till-"here the regional strike can be detected they do not necessarily conform. They havehas-e been less ati'ectdaffectd by granitieationgranitization processes than the roeitsrocks around them,them. though there is a marked increase in the concentratit‘ntconcentration of amphibolitic inclusions in the migmatitcsmigmatites approaching their boundaries.boundaries, and t'cispathicfelspathic yeinsveins tniectinject them,them. especially along foliationl‘oliation planes where they are present. It is thought that these rocks originated from cross-cutting,erossscutting. pre-metamorphism,prenmetamorphism, basic sheet intrusivesintrosiyes into the Basement System. Being originaliyoriginally composed of a mineral assemblage stable at highItigh temperatures they havehate been less drastically ttiteretlaltered than their hosts by regionalregions; metamorphismmetamorphsin and metasomatism.metasomatisrn. WhenUs’hen much of the surroundit‘tgsurrounding rock yytiswas being profoundlyproloundly changed and in part tnobiliaed.mobilized, these major maficmatic units remained itsas competent rafts,rafts. often distorted and occasionailyoccasionally pulledpull L..d apart.apart, but essentially unaffectedttnarlected apart from recrystallizationreerystaliieation and retrogressiyeretrogressive metamorphismm‘tamorphism fromt'rom a near-doleritenear-doietite constitution to that of plagioelaseplagioclase amphibolites. The major outcrop ot'of plagioclase amphiboiiteamphibolite in the area forms the ridge of the hill at Algabbyet. lGoodGood esposuresexposures ot'of hornblendic miginatitemigmatite with a high pro—pro- portion of amphibolitic schlieren surround the hill.hill, oyerlyingoverlying and underunderlyingying the amphibolite,amphibolite. 1tyhichwhich occurs as a steeply inclined sheet withsaith a generallygeneraliy southerly clipdip. The sheet has been estensiyelyextensively faulted at its eastern end. The plagioelaseplagioclase amphibolite is fine-grainedline—grained and fairlytiairly uniform,unit‘orttt. locallylocaily distinctly foliatedi'oliatecl in outcrop,oLtIerop. but only liaintlyfaintly so in hand—specimen.hand-specimen. {'ittt'netifet'otnGarnetiferous layers oectt"occur sporadically. Specimen 34/208,34 ens. from the eastern end ofoi" AIgabbyet,Algabbyet. displays bothboth garnetgarnet. andanti pyrite in hand-specimen. Inltt thin section it is seen to consist of 50it} perper cent of lighttight green hornblende,hornblende. the remainder being mainly plagioclase with1it-‘ith subordinate.subordinate ooartrquartz and pinkish garnet.garnet, the latter enclosing grains of sphene.sphene, quartz and iron ore. Accessory minerals include clinozoisite,ciinoroisite. sphene,sphene. zircon,airctt-n. apatite and pyrite. Specimen 34/17034 51W} from the peak of the same hill showsshots-s some 65lb? per cent of hornblende and quartzquartz. is more prominent than in the previouspreyious example. Ais fracture-zone crossing the north-western part of the amphibolite exposure-exposure, has been infilledinhlled with iron ore and now consists largely of limonite bands and nodules withyyith patches of strainedstratnco' quartztgttart? mosaic (34/171).[34. Hit. . 18| h The eaiiterneastern etteiend atof the er-iptwtireexposure isit. etttcut h;-by at“.severalerai quartz t'einti.veins. 'These'ht-rte are ttiatinetitt:distinctive in appearanee.appearance, heingbeing Hi'lditl't'ltisheared antiand pemaeriaingpossessing a eellularcellular atrueture.structure. The euartrquartz ir.is granular and retainedstained airingalong the ahear-planeashear-planes h}:by aeetattdarysecondary ironirdrt urea.ores, presumablypreattntahit' derit-edderived tirnrnfrom it‘nttiron exideaoxides taror pyrite that nriginallt'originally filled the eavitieacavities that newnow git-'egive the veinaveins their nin‘euaporous atrueture.structure. TwitTwo and a halthalf tttileamiles attttth—eaa:south-east tit"of KipkarrenKipitarrett rnarl-tetmarket andtheranother plagit‘ielaaeplagioclase amphi—amphi~ htiiitebolite handband iti-is eapnaedexposed in the t-‘itliejr.valley, and etttcut nofffi reto the nrtrthnorth by a H.Irl.—S."r‘t".N.E.-S.W. .t'ault-fault. Hlt ista variablevariahle in hand-specimenltand-apeeinten {3'4(34/405)fiiijfi} ahttwingshowing 'leucocraticleueeetatie segregationsaegregatiena surroundedaurrttttnded ht-by gt'EtLTl‘tthllgreenish pyrnaene~riehpyroxene-rich patehea.patches. The reekrock isiri eernpeaedcomposed plof hornblende,ht‘irnhlende- pale Liittp‘rrtidit:diopsidic pyreaene.pyroxene, garnet.garnet, quartaquartz arras mosaicnttiriaie pateheapatches and piagieeiaaeplagioclase atof the eentpeaitinncomposition ut'of haaiebasic andeaineandesine Ari...An HI' .«"’tta'e-:.~ittir}'Accessmy tttineraiaminerals ineludeinclude elintw.tii~iite.clinozoisite, apltene.sphene, pyritepyri'te and ealeite.calci te. An.r‘tn deter-tipoutcrop ei"of a .iittilat‘similar their.rock (34/199).34 lie}? isEa etttcut hw-by thet'.he KipltarrenKipkarren rit'erriver tineone .andand ;:_a halthalf milesrnilea nerthnorth at”of ChenutuwetChemnowet market. The reel:rock enntainacontains aprnesome riltl40 per eentcent harnhlende.hornblende, it]20 perier eentcent garnet.garnet, it}30 per eentcent 'plagioClase,nlagieel:-t~ie. «ititngtrrlinatesubordinate rniarttr.quartz, epidete.epidote, die-pridediopside antiand aeee.t~atr:.‘accessory magnetite and aphene.sphene. (b)it'll] Do/erites,i'rjri'i'lt'-":'.".-".:~'. r.-'£'.meta-do/erites{ti-Fifth} -".-'-."r’.l {USH-and Fit-'F'tirr'ftnorites Rockslittelta oftit" thisthe; grnttpgroup neeui'occur nee...-:;tttiaii'roccasionally aaas tilt-liter»dykes L‘I‘L'L’T'over the wholew'htile extent hrof the Basementi-iL'Aieitteitt .‘riyatemSystem within the area,area. and were seenaeert ettttir‘tgcutting the granite (itof the south-west,Heath-West. thnttglithough notnet the Nyanzianrat-'aniiian volcanictaieanie rocks.reeks. Outcropstittierupa are smallatnall and irregularirregular. in ahapeshape and the dykestiyltea' altetwshow little regionalregittnal trend. The exampleeaan'iple traversingtra'i-‘erriing the easternCt't'réitii'l't Hittpt'.‘slope ttt'of .-'tlgahhtretAlgabbyet.- followsrnliewa a provedpt'ttt'ed fault-line.fault-tine. .r’tA dit'ir-iier:division til'of the apeeiriten‘tspecimens atJC‘iitlttLLtLisectioned intoiutt‘l tit-titwo typeatypes it.is PLHSlbiEipossible; theaethose with dirt-the.olivine, antiand thoseii'ltlth': with uuarta.quartz. ExamplesDiameter; withoutwithnut olivinenlit-‘int: parentoccur in whichwhiea garnet isiii present-present, prtti'tahijsprobably indicatingittdie.i!int_t that thetlie intrusion nl'of thosethtwe particular dykesdyitea earnecame before the completione-Jn‘ipletittn oftti metamorphism.Itltfilttttitif'pillaltt. SpeeinienSpecimen Li—l'titi34/88 iiI'UIt‘lfrom hailhalf a rulemile mirth—eastnorth-east Lil}:of KapsabetHapaahet iiiis typieaitypical titof the t_‘._tlt:'L]"[Iquartz tittidolerites.flriit‘h. Inin 'riantt-apeeinienhand-specimen a medium-gritint-timedium-grained blackhlaeit rock,rnelt. it isiii aeenseen in thin aeetiensection toin consisteunsiat et'of reughlyroughly ertualequal pt'epertienaproportions et~of interlockinginterleeking piagieelaeeplagioclase priarnriprisms up into 1.5 rnrn-mm. in length in peikilitiepoikilitic relatienrelation tnto eiuateraclusters pfof attgiteaugite eryetals.crystals. The plagioclaseplagieelaae has the enmpttcompositionfiitittn An44'Fan... The attgiteaugite isia DUCT!often twinned.twinned, and diataiayttdisplays eeleurleaacolourless eeireacores with mauvett’tatlt'e [titanifer't'iua'i’l(titaniferous?) eutei'outer teen-eazones duateddusted with minute ineitiaittna.inclusions. Greet]Green amphiboleamphibdle formsterms a narrownarrnw intpereistentimpersistent fringetriage aroundaruund the fresh pyreaenepyroxene eryataia.crystals, and a rather hetterbetter det-‘elt‘tpeddeveloped reaetittnreaction ritnrim atof the aatttesame att‘itahibdieamphibole attt't'dtlndiisurrounds ironirett et‘eore eryatalacrystals tatof elerletalskeletal habit. ItA ver‘j:very Rtttaiismall arrtuuntamount nt'of quartaquartz eeeuraoccurs interrititially.interstitially. Retreat;Rocks atof aimilarsimilar ettntptwititincomposition ineltttieindlude .7434/102Ill? t'rnntfrom eaHt.east atof the.the read.road, fionefth”: and a half rnilerimiles nt‘trthnorth elfof E’I'LigttttMugun- doi,I; ei. Lil-i,34/119l 11:1 t'rttrnfrom halthaIf a mile earthnorth atof TiidhttrTilolwa, and 34_’l?434/174 fromlirtirit haltha'lf a.'1 mileri'tile south-westaettth-weat titof {..'het'itttriwa.Chemuswa. Inin .irilfltltt34/200 t'rt'trnfrom one and :ta halfiralf tttilerimi'les nttrthnorth efof Li‘ltentntttt-etChemnowet ittarketmarket mostmeat. efof the pyroxenept'ret‘tette i'iELt-thas been'tteen replacedreplaeett byht; red-brownrett-lart‘twtt hietite.biotite, skeletallakeletai ironireirt oresurea and eLlhedraleuhedral garnet eurreundedsurrounded by.by, eror aaatteiatettassociated with green amphiheieamphibole and ehlerite.chlorite. The remainder ut'of the rne’erock e-an'tiritaconsists ett'of weN-twinnedwelt-twinned fresht'reirh plagiodlaseplagieeiaae jtrin prisms“irrir'irnri up tnto 2 rain.mm. in length, and neither attattaquartz that“nor tutti-hieolivine waswait :iee‘n.seen. here-airmenSpecimen Eilf'34/231fliw’l fromthreat half a rudemile aeLtth-weittsouth-west titof KiltttniKilibwoni it;is attme‘wl‘tatsomewhat Sitt‘tilat'.similar, thttughthough n'itteitmuch morentt‘tre eetat‘ae—grainett.coarse-grained. [rtIn additie-naddition itll retainsretains rnuehmuch et‘of ita‘its eriginaloriginal pyroxenepit-'rtueene ariaand hashaze. nttno garnegarnet.. SpecimenHpeein'ien ."tii-"l‘dj34/185 trdtnfrom eaitterrteastern Algabbyet.fltlgalftt‘ifi'et eat't'ieacarries a high proportionprepdrtidtt ut‘of ferro-lierrtt— magnesian:r'iagttteaiart n'titteralaminerals and hiis typiealtypical rat"of the.the tilivineolivine ddletitea.dolerites. In thir-ithis rockrt‘Iel-t the Dil‘v'iolivinesflefi are largelarge fresht‘reah euhedra with crackseraeita accentuatedaeeeatttated byh}- granttleagranules tatof blackhiaeit ironirttin tire.ore. SuhhedralSubhedral titatatiteenstatite eryatalacrystals are abundant. PrimaryPrirnat‘j: ironir'tnt tireore lt-iis t‘idtnot ettttttt‘tttncommon and is[H aaatteiatedassociated with red-browned—hrett'n biotite,hietite. and progressivelyprngreasit-‘ety aura-artl-deereaaingoutward-decreasing eattnetienextinction indicatesindieatea that the labradoriteizihratlerite eryatalacrystals are aened.zoned, with increasinginereaeing andasoda epntentcontent uutwarda.outwards. "theThe nature erof the pyroxenepit-retiree indicatesinelieatea that the rocktheir enuldcould behe ettttaideredconsidered areas a.1 miern—nerite.micro-norite. ...-- 1911:1 A.-"1 .11i111i|:11'similar mineral111111111111 11$nt:111i:111111_:.11111assemblage, but with'.1'1111 a'.1 rather111111.11 lower11111.1: proportion[11'111'111I'Li11n of11t' ferromagnesian1'1'1'11111111g111::.i1111 minerals11111111111111 is1.1.1 displayed1.111111111111111 by1131' 34/104,34.“ 1114. a:1 specimen11111111111611 obtained1111111111.:11 from1111111 the1111: most1111.111 southerly:1111111'11:1':.1' of111 three1111'1'1' dykes1111-1111111 west11.-1:111 of111 the1111: Kapsabet-NandiK11p111111111—1111111111 HillsHi1111 road,1111111. one1111: mile111111.: north11111111 of111 the1111: Mokong11.111111111g river bridge.1111111111. The coarse-grained11111111111-g1'11i11111i nature111111111: of111' this1111.1. rock11:11:11 111111ijustifies1:1. inclusion1111:ii:1.11i1'111 within111111111 the1111': gabbrogal-11111: group,1111111111. and111-111 on1111 the[1111 nature111111111: of111' the1.111: predominantp1'11111111'1i1111i1t pyroxene{.11-1111111111: it can1:111 be111: classifiedCi.11:111i11111_i as1.11:1. an1111 olivine111i111i11: norite.1111111111. ThisThis coarse-grainedcai1rsa—gi'11ii1e1i rock11.11111 has11.111 felspars111111111111 up11;: to111 4 mm.111111. '.-11'111:1:.'across 11ndand contains111111111i111. clear1:111:11 euhedral11111111111111 pyroxene11111111111111: and111111 clouded1111111111111 labradoritei11h1'1111111'it1: (An62)t.-’1111,.__._1 in equal1.1141111] proportions.1:11'1111131'1111111. TheTh: pyroxenepy'rflxflnt: is faintlyiaimi}. pleochroic11111111111111: enstatite.1:11:11111il1:_ The'1'111: olivine111i1-‘i1'111 isi:'. subordinate1.1111111111111111: and11111:] is111 in roundedTULLEdtILi grains,grai1111. altered1111111111 111to ironi1'1'111 ore1111: and in part13.1111 pseudomorphosedgamed-1.1111111111111111} by111. iddingsitei1'Jcii111-j:1it..: and:11111 serpentine:11p1:111i11-:2 minerals.11111111111111. ItIt has11.11:. developed111:1'1'111111'11 narrow11111'1'11'111-' 111111111111111iti'1'amphibolitic reaction1111111111111.rims11111:: where11.-'1111'111 enclosed11111111151111 in111 plagio-1111111111- clase.11:11.1111'. TheT111' association111111111... 11111 of111 iron111111 ore1111' and111111 biotite11111111: is1:1 again1113111111 present.[1111111111. A.1111 rock1111111 representing1'11111'11111'1111ng a'.1 much111111111 altered{111111111 igneousig11c1111:1 intrusion1111111511111 of111 near-dolerite11:111-111111111111 composition11111111111111i11t1 is1.11 34/173341,."1TL1 from1111111 one11111: milett'1i1: west11.-1:11 of11f Chemuswa[11111111151111 market.11111 $11111. ItIt isi1. medium-grained,mc111111111g1'11111ed. speckledHi1eck1fid black1.1111111; and111111 white,1.1111111. and1.1111 11111011111111.unfoliated. Inlr'. thin 111111111111section it isi1 seen1.11111 to11': consist1:11:11t of111' 111140 per1111 cent1:11.111 hornblende,11011111131111: 1.1111111:partly as11:11 1111;:large 1:1'}.:11111:1crystals 1.111111with patterns11111111111 of111' lines1111:: 111ofcIusters1311111111111 of111.r 111111iron ore1111.1 inclusionsi111.'11_'l11111.1111 (almost111111111111 certainly1:111'111i11l11' thrown1111'1111'1'1 out11111 on1111 conversion..'-.1111'111'11i1111 of111 pyroxene1111'111111111: to1.11 hornblende)1111."111—111111111111 and11:11.1 partly111111111: as11.11 smaller111111111111 clear1:11:11 grainsgrain: in a'.1 mosaic111111-111i1: with111.1'iti1 quartz.111111113. Biotite'Bifltit: occurs111:1'111'11 inter-growninter-$111111 with1111-1111 the1111: hornblende11.111111111111111: and111111 as1111 thin111i11 independenti111111pi11'.1.11:1'.: plates,111111111. while11.-'11i111 almost1111111111 colourless1111111111551 garnet311111111 crystals111115111112. and1.11111 aggregates11313163111111. are11111: scattered51211111111111 rather.":-1ti'11':' sparsely1111111111111 through11111111311 the111-.1 rock.1'111'11. TheThr: lightfight minerals11‘1i111.'1'111:~'. are111-.1 quartz1111111111 and111111 .t.'1:i:1111ir_felspar. Another1111111111111 altered,1111111111] but1111111111.not metamorphosed,111111:111'1111'1111-.1:1:11. medium-grained1111:111.1.1111-f.11'111111'11 dolerite11111111111: invadesi1111111111 and111111 isi.- faulted1111111111] against the1111: granite11111111111: in111 the111: south-west,111111111— 1.1111111. south111111111 of111" Ndurio.71111111111. Inspectioni11:.111:1:ti1111 suggests1111'1g11311 that111111 the111: rock111.211 (34/290){Gal-"21.1111 originally1'11'igi1111i1'1r possessed11111111111111.1111 an1111 approximate.1'11'1'11111'111: mode1.11.1111111 of1:t_1_:11_.='111:1111111.4i11pyroxene 40 perp111 cent,1:1:111. ironi1111'i ore11111 (ilmenite)(i11111111it1.1}.5'1 per[1111' cent11111 and111111 plagioclase11i111.1,i111.'i.'.1.111-'-. 5511:1 per11.111 cent.11.111. LittleI_i1111 of111 the111.11 pyroxene1.11.1'111111111111 now11111.1. remains,1'1:1'11'..1i11:1. the111: majority111111111111. of1.1i the1.111111_1.-'11111i:.crystals being111111151 altered1111111111111 to111 .-11'111._'.111ii_11111:amphibole and:1111'1 thet 1' greaterg111111111' part111111. of111' the1111-1. ilmeniteii1111:111t1' now1111111 occurs1111111111 as11:.- leucoxene.11.111111111111111. The'1'1111 plagioclase11|11g11111111:.-: isi1. highlyhighi. saussuritized,1111111111111'i1i11111. but11111 the1111' original1111511111111 twinning1111'i1111i11g. isi1: still.1.tiii visible.1.-i:~'.ib11:_ Micrographic1‘.-'1i11'11gr1111i1i1: quartz-felspar1:11:11't'.1-1'111:~:_1_1:':1 intergrowthsi111111g1'11111't1111 occur111111111 inter-11111::- stitially.atitiaily. (c)1:121 Amphibole1‘11.?1'1'31'11.'I.1'I}:'}_I";" Rocksf-Efjt'kni (i){ii- Hornblende11’111'1111111111'11' 11.1.11111'1'11'111'.1'Epidiorites T111:The 11111111:name h111n11|1:111:11:hornblende epidiorite1:}1i111111'i111 isi:.1 111111:here used11111111 to111 111111111111:describe rocks11111:: 1.'1':1'1:.i1i111'11dconsidered 111to be111'. of111 igneous1111111111111 origin,origin. but now[11:11.11'1111111'111'1altered 111111and 11111111111111:consisting mainly11111i1111.-' of1.11 hornblende.11.111111111111111 Rocks11111111111 111'of thisthi1.'. 11'. type1'.-11:11: are111111 recognized1'111'111111izeci ini1'1 several:11:1-'+:1'-.-11 111111111smaH, poorly1:1111ri1' exposed1111111111111 outcrops1111111111111. west'11.11. '.111 111111and north-east11111111-1:11.111 of Kapsabet,11111111111111 and11111.1 against11gai11111 the11111 boundary1111111111311. 111of the1111'. Nyanziani111. 1111.11.11 rocks1111:1111. one111111 mile111i.'1: 11:11:11east of111" Kaptumo.11"..1511111'1111 SpecimenSpecimcn 34/83311113 from1111111 two111-'11 miles11'1i11-11'. west1.111111111of Kapsabet1111111111111: is1:1 a'.'. highlyghi1'1-i1' altered,11111.11:11. friableI‘1'11111i1: rock,111-1'11- green111111111 ini11 colour11.-1111111111111but flecked11:11.'111'1 with white.11'111'11'. On13111 microscopefi1i1:1'11:11'11_r111 inspection1111111'11 111.11 thet11111'1:1':1.'rock isi11 seen121111.11 tot1: consist1:111:111i1'i of1'1-f an111.1 irregularirregular mosaic11111:.11i1: of1:11 hornblende11111111111111.11: crystals1'1—1'11; 111:1 forming1111111i1'11: some1.11111: 801111 per11:11:11111cent of111 the111 rock,111111;. togethert111g1211'1111 with111'it.1 granularg1:-1111.11:11'1'pi1l111:.epidote, accessory111:1:1':1.~111."'_.-111.111.111.11.plagioclase .1111:and quartz1111:1111: carrying1' 111111111 con-.1111- centrations11111‘111111111111 of1'11" hair-like111111—1i111: inclusions.i1'11:i11:11111111. Specimen 34/93.11-1 1113‘. from1111111 a.1 mile1111111 further111111111 east11:1:1t isi:1 a'.1 similar11i111ii-.11 rock.111111. On|[“1111 inspectioni11111c111i1111 the111E hornblende11111111111111.1111 mosaic,11111111111: which11.-'11i1'i'. again11:1:1i111:111111i'..11t1::1constitutes some111111711: 80‘.1-iii per5111' cent1111111 of111" the1111: rock,111111;. is1.1 seen:1111111 to111 be11: more1111111.: regular11211111111 111111and 111to consist11'-11.111111 of111 larger1:11'g1'11'11'11g11iragged plates.1111111111. QuartzEJ111111: and111111 plagioclasepiagi11111111111 111'1'111occur interstitiallyinterstii i11ii1- 1.111.:1and locallyi1_1-.:1i'.i1.' form1111111 aggregates1111911511111: of:11 crystals1111-1111111: associated:-1:1:1111'i1111:1:1 with 111111111small quantitiesquantitie: of11f epidote.:pi1'i11t1: J The'1'1'11: rock1'1:1-:.'11; forming1'111'111i1111 11a sma'H111111111 1:11.11111'111'1outcrop .1111:one mrle111i]..- 1::11.1east .11of Kaptumo11111111111111”: (34/297)1'1-11.31.11} is1.1. 1111:1121}closely related(211111111 to111 1.1111:the previousp:1:1.-'i111_1:. 111-1111111111111.examples. H111'nh11:111'i1:.Hornblende, pleochroic11111111111111 :1: 1111111from pale11111111111111.1—111'11111bottle-green to111 11111-1111; 111111 11:11:111i1' 11111111111. I yellowish11111111111111 3.311111green forms11111115 a11. loose11111111: 1111111111i11ti1111association of11111111111111'111subhedral plates and mosaic patches. Quartz,11111111111. [11119111113511plagioclase 111111and 111111111111:muscm"ite occupy111111115111 interstitiali1111:1'1.'ti1i'.11 spaces,1111112111.. together1111111111111 1.11'ititwith subsidiary:111‘11:1i1ii111'1.' epidote.1111111111111. TheThe. 111111.1i1i111111:amphibole constitutes1'.-1111.111itiit'111 some11111111 70Ti} per1111.1 11:111.cent 111'of the1111: rock.1111.111. - I 2t]20 {iii(ii) Aertriet't'reActinolite b'pr'rlr'eriresEpidiorites This reek—typerock-type is alsnalso eensidereticonsidered teto represent the alteratienalteration preduetproduct efof nriginatorigmaI intrusiveintrusiye igneeusigneous rocks,reeks. whiehwhich eeeuroccur in twetwo masses in the hiyanzianNYainzian veleanievolcanic rocksreeks eneone and a half miles seuth—westsouth-west efof HeyeKayo hill. Inin hand—speeimenhand-specimen Gal-"29%(34/294) it is a highly traetured.fractured, eearse—grained.coarse-grained, basiebasic reei-trock eetnpesedcomposed raainlymainly et‘of lustreuslustrous blaekblack amphibeleamphibole erystals.crystals, and with muebmuch seeendary'secondary pyrite enon fraetttrefracture planes. inIn thin seetiensection the amphibeieamphibole preyesproves teto be aetineliteactinolite and eenstitatesconstitutes semesome it]70 per eentcent efof the reek.rock, while the remainder is eempesedcomposed mainly et'of variablyyariably‘ elearclear and sanssuritiaedsaussuritized labraderitelabradorite and suberdinatesubordinate ireniron ere.ore. {El(3) PEGMATITESPeest.-s't'i't't;s arseAND GraterGIANT Ut_.:_s'a'raQUARTZ ‘y’tttnsVEINS Pegmatites are t‘lliof widespread tieeurrerteeoccurrence iniii the BasementBasetttebt Hysteria.System, being een-con- spieueuslyspicuously develepeddeveloped bethboth in the migmatite sanezone and areundaround the granite and granitnittgranitoid gneiss in the seuth.south. Utter]Often it is apparent that they have been derelepeddeveloped in sitesitu asassegre-segre— gatiens,gations, but elsewhere yeinsveins nt'of pegmatitiepegmatitic material have intrudedinvaded the eeuntrycountry rock.reek. Fori’er eens'enieneeconvenience they are consideredeensidered teg'ethertogether here. Pegmatites eeeuroccur as isolatediseiated b>Iebshlehs and swirls in the nerthernnorthern migmatites,migrnatites. and further seuthsouth as anastemesinganastomosing netwerltsnetworks et'of veins,reins, orer massive eeneerdantconcordant sheets. These reeksrocks are ettenoften less readily weathered than the best-reeks.host-rocks, termingforming upstanding eatpesures=exposures, and presidingproviding eepieuscopious heat.float. TypieallyTypically they are eempesedcomposed et'of euartaquartz and tielsparfelspar intergrewths.intergrowths, theeghthough small garnets were netednoted in several instanees.instances. lCiriaritGiant white quarts:quartz reinsveins int-irreribarren t'lliof ttiitiernliaatieitmineralization were mapped euttingcutting the Batte—Base- ment System gneisses in ses'ei'alseveral plaees.places. 'l'heThe veinss-eins are usually eempesedcomposed nt'of eearslycoarsly erystallinecrystalline glassy 1whitewhite quartsquartz but the example seuthsouth tit'of Baratonliaraten is efof tinesgrainedfine-grained granular texture. I 5. 'l'ertiaryTertiary The stteeessietisuccession titof Tertiary'I'et'tiut'y resultsrocks it:in the Kapsahet.Kapsabet area is sutiitiiariaerlsummarized in thethe tattletable helnwbelow and etii'ttrastetlcontrasted with the sueeessiensuccession suggested terfor the area east tilof the Kat-'irtmrleKavirondo {LiulfGulf by“by Shael-tletrmShackleton twil-(1951, p.p. .lftl350 and p. .ltifil385) at‘tdand eert'elatedcorrelated with the.the stteeessiunsuccession tilof the Tinderet['inderet suite iii?of the KerichoKeriehti area r'eeegriiiedrecognized by HingeBinge (liltil(1962, Tablel'a hie 11-p. its.38, pp. 37-3-9.27-29, ill].39). {t}(1) s'ttett'eseMroCENE heels-testsSEDIMENTS The widestoldest reeltsrocks tiseriyirigoverJying the li'I'eearithriaIiPrecambrian in the area are sediments et'of MioceneHie-eerie age.age, whiehwhich are.are seen nnlyonly in small eapesnres.exposures. In the seuthsouth they termform the eentinuatiencontinuation tit"of sediments in the SengherSonghor area deseriheddescribed ,byby Kent {Isl-t4}.(1944), ShaekletenShack~eton 171951](1951) and Binge {1962).{1.952}. The age titof sediments t'tirmitigforming estet‘isis-‘eextensive euteretpsoutcrops in the KavirondoKat-'irrmde Gulf area.area, in partieularparticular RusingaResinga Island,Island. has been established as MioceneMieeene (Hepweed.(Hopwood, 1929;l'ifltl: Kent.Kent, 1944; Shaekleten.Shackleton, 1951; Whitwerth.Whitworth, 19:33]1953) and eerrelatiencorrelation has been made with the lithnlngieallylithologically similar beds at SengherSanghor and Koru,Kern. where t‘nssilfossil ey'iderteeevidence suggests that depesitiendeposition was eentinedconfined teto LowerLewer MieeeneMiocene times. HhaelcletenShackleton pnirttedpointed nutout {lllf'iL(1951, p. 365}365) that the beds at Htinghet'Songhor are meremore tuft-attendstuffaceous than thesethose at Koru,Kern. and eertainlycertainly in the present area near its seuthernsouthern margin at the feetfoot efof the searp.scarp, well eerthnorth efof Sengher.Songhor, the seuueneesequence eensistsconsists mainly etof waterlainwaterlaiii tufts.tuffs, with eeeasienaloccasional impure limestones.limesttmes. The eeeutreneeoccurrence ntof these MioceneHieeene beds suggests that in early MieeeneMiocene times lakes esistedexisted in hellewshollows in an undulating tepegraphytopography termedformed titof PreeambrianPrecambrian reelts.rocks. HasalBasal eenglnnieratesconglomerates attdand sandstenes.sandstones, representing depesitiendeposition efof debris earriedcarried in by terrentialtorrential streams frernfrom neighbeuringneighbouring hills.hills, have been deseriheddescribed at HeruKoru (Kent.(Kent, i944.1944, p. lite:106; Shaeklettin.Shackleton, 1‘45].195I, p. Edit]364) and may weliwell underlie the sequel-teesequence in the present area:area; m:the junetienjunction between the h’ilL‘lCEE‘tEMiocene sedimentssediments andand thethe Underlyingunderlying gneisses was newherenowhere seen. Intermittent yeleanievolcanic aetiyity‘activity later resulted in the depesitiendeposition efof aggtnmeratieagglomeratic and tutl'aeeeustuffaceous beds.beds, and in meremore quieseentquiescent phases less enmmen.common, alternating tessilifereusfossiliferous elaysclays and limesteneslimestones were laid dewn.down. The majermajor eruptive periedperiod efof 'I'inderetTinderet then ensuedensued and the MitieelieMiocene depesitsdeposits were inundated by set-'eralseveral hundred t'eetfeet eiof etiarsecoarse nepheiinitienephelinitic agglernerata-agglomerate. ~ - 'l1.u11,-xm-'TERTIARY SUCCESSIONSLIH'I-Hrsqjm INIn THENH KAPSABETKarla-ml 'I ANDAM.) SURROUNDINGHLJIUUJLMJ'JIHU AREASR. H l - A .-'. Tinderet'l 'jmimt‘l SuiteSniiu ofHI' KerichoIiut'iclm Area.s'krcu Tertiary'I'L't'iinr'}-' RocksHUN-d ofHf KapsabetKuymalurl Area{M1311 Tertiary'[:_‘r'liL1I'}-" RocksHUL'I-H eastL'ihl ofIn!" the[IIIJ Age {Hfl'lgt(Binge,fi 1962)WEE-7'} {lmrwm‘(present report)I'm't } KavirondoHUI-"il'illulfl Gulf(Iiulf -- IS(Shackleton,1;kL"L.|<_'l-.m, 1951)1‘.i I Z] Lower|.:'m-'L.‘r‘ PleistoceneI’Fciratmw'n: . . DecomposedHrunngmH-mi hilHiL'basic lavaJan-n flowsHUN-KN onm1 -- Kanolimm plains.plnim. PlioceneI’I incunu ...... BasanitesHElIHiIL‘E; nmfand tephritesEunhrilua BasanitesHusall‘litm ul‘of the1 l1.“ Mtetei"u-"it'umi valley\-';_|I|L.‘_‘~" lfpprl' h--'Iil._3u;-I1Lr . . . . I’f‘lf'n‘lcfinlih'fi Upper-- Miocene Phonolites ofHI~ 'I'J'H-iim'uiTinderet Melanephelinites‘x-hrln nuphulinitm LavasIAN-H3 {'11.of Tinderetl'il'lllu‘l'L't NephelinitesNuphulm Hm: (I’hmmlilig(Phonolitic nephelinites,l1£‘|1|']L‘li[']i1_Lfr~;. [Manilabasalts, nephelinites,lnrpllulinilua basanites,hzimnitcm PhonoliticE’lnmnliliuharm-1;:Him“)trachyte (Koru) melilite-bearingI'I'wliiitu—lmm'iIt}; 15-11%)types) Middle."v’! HM IL'. Miocene.Px-1i(}-;_'L.'i'|u . . . Coarse(I "w.”w-m: volcanicx-nlL‘tL‘. ngzulmunui'ulcagglomerate Agglomerate.-'\_g:glm‘lici'nlc N Ii(Nephelinitic.“NLi'lfilla‘iiIIiliL‘ ..fHu'JlEl-DIH'HH'rlil.IL'.,mela-phonolitic, ...... mela-nephelinitic,mulL1—i‘1-3phL‘JiI1iLiLu etc.) Tuffs'l'ul'i'ra. andnml KerichoKuriulm phonolite[wimmhlilv Uasinl':l~;in Gishu(Fight! phonolitesnlmnmlilux PlateauI"l.'!_l-::IH phonolitespimrmlihra. H(Losuguta-;‘-*~~l_l_!-_.'-'.‘1J'[.'l type)Hut] Tinderet1 imlLf'Hrl LavasI..L'l‘.";'.~. (Augite-rich'3--""“‘H_'-'.il~:—I'iu:h nephelinites,H'L"|'1:r'ILTI“Tilt?“ nephelinetwpiwiinu basalt,Instr-gun. olivinewhy-i1“; basalt,|-_,;N|“= h-plwflc, n:ru]ilil«.:--lmm-m!: 'j’l‘JC‘re'fl -- tephrite, melilite-bearing types) ! Coarsel: lutl'HL‘ volcanicwlL'umu agglomerateLlj_',§_‘,|{1IHL'!';'+l_L‘ Agglomerate.-'\ggFtI'HT‘IL:I';Ii\L' Nephelinitevhuliniic ;_I.g'._1_r.fnlmagglomerateI';_1t-'..:- umland lutuffsfl'r; (Nephelinitic-,{Nunhuii11i1jv--\ mela-phonolitic,mum—{11mm)lil.inf. mela-nephelinitic,lHCliE-‘Tifl‘l‘ldIl'liliL‘. etc.)um.) Lower| m'-.'L.':r' MioceneNHLJL'CIIL: . . MelaniteTk-‘h'lmallu tuffshill}; and :|3.__r..3g.,1:'ml1.1-._"r'{H.L;"~agglomerates KoruIimm Beds|'§.-.._ta[:~:~ MioceneM it"ZIUCHLI' HI...'L|ir'HL‘.r1IHsediments Koruhunj'u BedsHuh} H(Limestones,inuxrstrunbf.~ biotitichinlirh; tuffs,lul‘flu'. £|.im¢_'-~;l+.mu.~;.(Limestones, iiiu'wtilil;biotitic tufl'mtuffs, (Limestones,[[11:1L‘EIHI‘ICH. biotitic!‘nin1itu-lul'i'.~;.tuffs, marls,H'ILIr‘ln. ashnah beds,hudrn micaceousJ'IHii"LI.£..'L‘£.JLJ:--. bleachedlwiuzluhL'Li tuffs,milk. marls,maria. Hlill'lH.marls, Hihhsilts and clays,;'];'1_~,.--.~~;. etc.)L"i~.".'+ a_:=}IIH<.lliqlc_'L1consolidated L'|::_~_,-'r~;.clays, etc.)ICE-3.] 3411asands with figneissicll-Sinh- boulders)mullet-1'3] ...... __n..._._. F._... ._ . .. rut-u... _ .. —— --— -—_... (Dotted[HIT-HUN lineslimb. indicateil'luliufnh‘ unconformity)lli'lL'Hllf'l'f'lli'llllf‘u'Il 22 More.‘1-11'11'1': than111111". .11:100111 feet1'1-1.1: 11"of 11'1111':-.ashes and111111 1111111.tuffs, most11111111 1.11of which'.1-1111;11 are1'11‘1: apparently11111111111111} waterlain,1111111111111. are111': 1.1311111111:1'_1exposed in111. the11111- 111111511.1111eastern 11111:.side 111'of 112.:the Ainopsiwa..-‘1111'-.1'.111.111111'11 vaHey111111111 1111on 1111':the H1111'111131‘11southern 'boundary11111111311111: 11fof 1.11.:the 1111:11.area. 111:1:These :11:are 1111111111511oveJ:'!lain 'by1111' '11a 11:111111:11.11111-'sedimentary 11:11'111:111':sequence 111111111.about 10011.11.] f1::1feet in111 11111311111151.thickness 1:1111111111111gcontaining 111:1":1'111several impure11111111111: limestone11111:.1'1‘11'111: bands.1111111111. Up-streaml.'r.1.11[11':11111 111'of the1111: road1111111 bridge111111111: 111-'13-1'over 1.111:the Kamaasae,K1111'11'1111111:. 11111111111111stratified 11:11:11ashes 111111and tuffs11.11111 1111:are 1211111111111exposed 1111111111111111111'sporadica'1ly 1111on the1111': 1111111111:r.11southern bank1.1111111 111'of 1111:the river111:1 111111and 11:1on 1111':the 11:1Wllside1.1111111 11".1to the[111.1 111111111.south, 1:111but it11 is111 1111::1often 11111111111111doubtfull whether1.1111:111:1 111:}:they 1111?are waterlain.1111111111111. 111'}(a) Limestones11-111.111'11’1-1.111% Th1:The 11111:.111-111:11limestones 111'1:are 1.:1'1111confined1111:11 11:1to 111:.the 1111113111111outcrops 111'of .'.‘1-'I1111'.'.1'.1111:Miocene 11:11.1;beds 11:111'near 111:.111111the foot 1:11of 111:the Nyando‘111'11111111 111111-1111.scarp. T111s'11'11'1:They are 11111111111:variable in111 11111111111111“.appearance within1111111111 their111:11' 1'11111:.1'1'.‘111.11'.-'outcrops, one1111': 111of which11'-1111:11 forms111111111 1111an important11111311111111: feature1141111111: west1113.111 111of the1111: road1111111 for1111" .1a 1111?:mile from111.111. :1a point1.1111111 111'11'.some'- 1'1-11111311111111111600 yards north'11'11'111 of1'11 111:the 11111111111111equator. A p111:pale buff,31L111'. well-bedded11.:11-111-11d:11 1111111111:sample from111111". :11:the centre1.12111: of111 this1111.1. outcrop1'1-1111:3111 (34/75)1'1—1 7.111 consists11111111111111 of1'11" weH-defined111-'1:11-1'11'11111.'11 'bands1111111131.; 111'of relatively11:111111':1}-' pure11'-.1111. limestone,11111:.11'11'111: with1111111 1111111111111:alternate broader,1111111111111. 11111r:more T.L|11‘111::1'1L1.11tuffaceous units.11111111. InI11 thin1.11111. 11:1:111111section 1:111:11:cailcite is1.1-; 111:1:11seen 1'11to replace1:11111-3: 111]]aN 1111':the tuff”(1111‘ fragments,fragmcnta. their111:11' origina:l1.'1r'1§_111111| shape111111'1: 1111111and size11111.11. ,being11121-1111. indicated1111111113111 ,by111-.1 11111113.:11'11'1111concentrations11111.11 1'11"of iron111.111 ore1'11: or1.11‘ 1.11111:olay particles.11111111:1:~'.. SecondaryL'~1:1.111111111‘1. apatite1111111111;11111-111171-111:crystals are present1:11:11: 111 and1.11111 fragments1'1'111'. 1' 11.11 and111111 crystals111-"11.1111. 1'11of yellow'_1':Il1111' 113111and 'brown1111111111 perovskite.33:111‘11111'11: At1‘11 11a slightly.11111111- higher11131::1' horizon111111151111 in111 the111: same1111111: 1171111111111:exposure 11a breccia1111;111:111 is1.1: present,11111511111. consisting1:1111151111111g 111'of limestone11111:..1'1'11'111:11111111111111.1111fragments 1.111111111111111cemented by11.111 1:111:11:calcite. 11111111111111.1111Specimen 34/315,3.4.315. 1111111from _111111just west1.11:11. 111'of 1111.-the Kamaasae111111111'11'1111'11: ,bridge,11111'1' is1'11 dark11‘-111.11 grey-brown31133-111'111'1-1'1'1 andIli‘ld is111' 1La recementedr'ié'L‘CFWW'id 1111:-;_.11'11111:11fine-grained fragmentall{Hi-3171111111111 limestone,.'..'111':1111111:. with111111 much11:11:11 1'11of 1211."the cement1:111:11‘1. «1111311111stained by1111 secondary11:1;1'11'1111'11'11' iron1111-11 1.11:.ore. East1.11.1.1 113'of :11:the 1111111road 'limestones1'.-11111121111111. 1'1171can 1'11;-be 11::1'.seen f'1in 1111:1111several 1111111?sma'll :71111.'1~'.1_1rr.-11.exposures. 1111'The Kamaasae11111111111171.1111: 11111-1river 1111.12.11:cuts 11a 11111111111111:111111.11:diminutive' gorge 111111111111through 111'11'11'1111'11'11horizonta'l 1.1111111111111111.sediments, 111111.11which 111111L111:include '11a limestone11.111111111111111." 1'1-11111band 1111.111high 111in 1111:.the 11:11-11:1111:sequence, :1a 11111111111quarter 1.11%of 11a 111111:m~le 1111up-stream1111:1111. 11111111from 1111.1.the bridge. On 1111:the =._'111_1'.111..1r.equator, 11:11.1east 1111'of 111':the road,1111111. '.1a 11:11:11series 111of 'bedded11:1'11'111'11 11111111tuffs 111111are 1:11p1111:.11exposed 111.in 1111'.-the 111-":1river bed,had. 111111and 1111111211111outcrops 111of 'banded111-111111.111 (limestone11111111111111: 111'of 11a few{:11 1.111111yards 'lateral1111:1111 1'.-1.11.1111extent 111-1:121:1'occur 11.111111111111111sporadically '11?at 1111113151111different 11:11:1115heights 1.111on 111-.-1111-1111111.-11.111113111'1-1‘111.the hillside to the north. A:'1. 111111111111:solitary 1111-11111fossil _g1'1~.111'.1;:-111'.1gastropod was1111111 11.11.1111found in111 '.1a highly1111-51111 1:;111:1-'1-.'1-.-1.'.11.11callcareous 'biotitic1111111111: tuff11111.54(34/78) in111 the1111: 1.11':'1'111".-111:dstream-bed 1'1a 1:11few yards1111111. west111:1.1 of1.11 111:the road,1111111. 1111:one and111111 a1-. half111111 m~les1:111:11 north111111.11 1.11of the111: 1'1-1111111111.equator. Exposures1'111111111411-11 111"of 'limestone11111:~1.1.1..111: remote111111111: from111.111 the:11: main111.1511 1111113111111outcrops 1.11.'1'.'1.11'occur 151.1111:some 11.1.1.1two 111111and :1.a 111111-ha!1f miles1'::1i1'111 11111111~1111>11north-east of1.11 the1111.- Kamaasae111111'11111'1'.::-1'.1 bridge,111111111: .'-'11at a1'1 height11:11:11.: 111'of over1.11:1 5,6001.111111 feet{:11 11111.1and some111111111 1,0001.1..'1"."i'i.| feet11:11.11 higher1111;11:1' than1111:1111 the111-1: outcrops1.111111111117111 west'11 :11. 111of the1.11..- road.1111111. Assumingj111-111.1'1111111'. that111111 1111111:aU the sediments11311111113111: 11'-1:1":were laid111111 11111131down in111 '11a 1111121:single 11111111111111-1111continuous lakeL111: 11or in111 fineighbouring:1g1'111111.11111g 1111111—11111Edlake-fHled 1111111111115hdllows 111‘.on the1.111: 111111-111-'111'11::11:sub-Miocene peneplainp:11:p111111 1111.111their present{11:11:11.1 1:1'111.1111:r'111_11:considerable 1111111111111::difference in111 :1:1-'111.1111'1elevation 1:11.11can be11: 1:111:11taken 11.11as '.111an indication11111111111111 111"of the111.1.- 1111'1111111111111':magnitude 111of rift1111 faulting11111111113 11111111;along 111:the north11111111 51111:side 1:11of 1111'the Kavirondo111111111111111 111111"gulf _g1'1111:31gra:ben 1111;1':since Lower1.111.111: Miocene.‘1-1111121111: 11:11:11times (Shackleton,15111111111111}: . 1951,11.31.11. p.111. 31111}.366). (b) Bleached Tuffs and Mudstones Muchf1-1L1c11 11:1'11'11'1'further 11111111north than1'1'11711111'.the Miocene3111111111111 1111:1111"outcrops mentioned11:11111'111:11 1111111:above 1'1a 11L111111'L'Inumber 1.1T-of 1.111171111111211isolated :.11111.'111111:.11exposures 11fof 11gg111n1:1111:agglomerate, 1.1.111tuff 111111and 1'1-1111.:white 1111111111111]:mudstone 1111111111.occur, preserved111111.111 111-ed in111 1111111111111.holilows in'.1'1 the11111" mild1111111 topography1:1;11.1g111p111-' 111'of the1111'.- Uasin1' 1111111 Iii—11111111Gishu plain11111111 1.11.by 1111:.the plateau11111111111111 phonolites11111111111111“. which1111.11.11 I . __ 1-.. , .1. -.""-:f'1."1.'1overran the[11L 11.11.11area from1‘1—11TH the11“.." east.11:111-1. Five1".111: miles111.2114 :11111east 111of Kabiyet1\111'1'1:1 a'1-1 1:1."1r"-1-1.11‘.:1'.11111'.considerable thickness1111-:111'11'1-1 of1':-1' friable111111.111: bleached1.111111111111111 11§1111111'1:11'1-‘.11agglomerate and11.111 11.111tuff with1111.1 mudstone1111111111111.- : bands,1111111111. 1'1.[‘.1}‘.-'11I'1:11“|T.111'apparent'ly waterlain,1.1.111:111=1111. is1'11 preserved1111;211:111: 11:11:11111beneath 1'1a tongue11111-31111: of1.11" phonolite111111111'111‘11: and111111 11.111111exposed.111111 11:1on both1.111111 the[11: 11111111east 111111and west1.11.1111 .111sides111.11 111of 11.it. Although.11111111'111gl1 11111111111heavily 11111111-over- grown,11.117111111. .11a tota'l1.111.111 11'111:11111'~1.1'1thickness 111"of 1301711'] feet1"1::1 :1'111can be111': measured111:1111111'1111 in:'11 111:.the :11111:111eastern 1111111111111;exposure, with1111111 a compact11111111151111 white1.1 11111: mudstone1111111111111: 'band111111111 attaining1111111111111: 11a t111:1111:1111thickness of1'11 -'-4 111:1feet preserved111':.11:1'11'1'_'1;1 near11:111' the1111‘:LE.- base1.111111- L 23IJ ILLIJ 111'of the sequence.11L'LJtIL-11Le. Amt-"111;:Among the 1111111.'11L:dtumbled 'blocks1111-1121111 L11at the 111111foot 111'of the 111111111small cliffL'h-E'T fLT.:11'111e11formed by111' —————-—-I-' the compact131111111.11L't mudstone11111111111111e band7:111:111 overlying1711er11111g highly111111111: frialJle113111111: and11t altered'L'1'LtL-re11 tuffs,1111111. a:1 boulder111-111111er was11'111. _n-L- [I found1111-11111 that1..' t containedLL1I'It1111‘Ied twot'1'1'1'1 poorly1711'11'1r11' preservedpt'e'LL'r'L'ed indeterminate11111eter11111'1111e fossills,11111111111. probablyhr1111:'1§'.'.1jL-' small1111.111 'lamelli-11-1711e111- __. branchs,1'.-r1111e11'1. which however111111-e'1-‘et' L111'111tteg1'1'11e11disintegrated 1'111on inspection.1tt1t1eet111h. TwoT1113 miles11111.1 furthert'L'LI'theI' south1L"-t:'-.1'. another:'11111ther 11111111small outcrop1'1I_:1.L'r111.1'.'of faintlyt':11L"tE:L ;-__'t'L-L'I';11Lhgreenish 1111'1e31e.blotched .-__.._--.. mudstone"11111131011: has1111.1 beenheeft preservedpt’e1er'1'eL1 undertLrIL1L1' the phonolite1111;.11'11'1111e :11tand is11' 1'.-1111'now poorly111111111; exptteedexposed init". the11':.L'I— stream-Ibed11.1rL-11111-he1'j (34/183).13.1, [3-31 — BothBeth consolidatedLL‘11111'11111111eL'1 L1L111'1'Lclays 111111and bleachedhZeLLL'heL1 tuffs111111.. L1:111a'lso occur1LLI'r within111111: 11 the KapsaretHt:t‘1:~L-‘1ret ForestPOWER _..... "-I "1 . '11 '11—- ..;‘L'.i 1:1'.,I.- - 1“,. (specimens11:1-L~..L.11L:111.1-134/216,.1111.-34/217),—1 -1.-..|.'1'1L1t_1'l_.l1'1-1.1.111L.L1IL111L1L11Lt'11'11LI'IC111L1113111—1111.".1"C'1'L‘L-L1L‘T'I1LTU11where it is difficult to determine their correct relation to the 1—-—— _I.'.111-::::11'11:tL-'.phonolite. Ez'L1111J—1'LL:111L'.Small-scale faulting1":111111111-4; is1.11 11.111111111'1L'L'1assumed 111to 11L'L'11I_1111account for1111' their 111111111'e1'11apparent dip1.1111 11:"of 1'11"45° S.E.,5.1.1" . 11111-1 2111111 the 1‘.-11:1 that they 1.1-L'L'.L1r 1:“1 the '121'eE'1rt'1-heL1 L1h1.'1'1'e the 11.'.1'L11:.1:t [31111311011113 1.1tItLr11p -.n-u-.-.—-I and a'lso the fact that they occur in the stream"bed above the lowest phonolite outcrop. r— A’1. 3411111;gillly south1'11'111th orof the main11111111 stream1treL1r11 has111111 1:.1111'11'e11exposed a'.1 small11111111 11111L111t1'i111esandstone lens1er'1.1.: (34/218)131211'1'1 inter-iI1LL'r- . beddedheLiL1L-11 1.11-t11L-L'L'1between the 1.11e'LLL:hL'-11IJleached 11111tuff 111111and 1:111'1'1121011e.dlaystone. (2)121 PYROCLASTIC1’1'111'11': 1.11.1'1'11' ROCKS1111111111: 1':'1:--'OF TINDERET"'l'1'.-L'r11-'.111'I The1111':- _eregreatereL1tL' r partp'LLrl of1.11w thethL- south-eastern11'111111-e111'11:r11 section:L'eL111111 of111' the area1111:: is1.1L composedL'L1111r1111e11 of111‘ pyroclastic1.11-'1"1".11':1'.1111L rocks,r1.'-L'3-L.1;. originatingL1r11111t T""LT fromtr111"-11 thethe volcanic111LL.11| centresL'.e'I"L'.re1'1 at1'11 Tideret.TidL'ret. The111.: agglomerates'.1-1::11'1'11et'11'1. and:1I11'1 tuffs11.111 accumulated'.1.LL."111"L1L111111:L1 on1:111. the'.h1:L111111.1111‘11111_L-:undulating surface1.1.11'111L'e of1.11 thethe pre-MioceneprL-h-11'L1Ler'1e landscape,1L1111111L11r1e. lbilanketing1111-11131LLt111g. the topography.1L1r11'1gr11p11'L-'. SubsequentHLIh1eqL1ent erosion1111111111 has11111. exposede.'1Lr.1111e11 the tops111px of1:11 thethe. higher BasementBLLHeL'I'Iertt SystemFifi-Rteh' hi'}ls,1111'..11L. which1111'.L"11 now11111.1. 11-11111-1111511.overlook vaHeys1LLliejL1. stiH11111?- mledt111‘e11 with'L'L'Ith volcanic1111;111:111: Llehrti.debris. Most11111.11 of111' the agglomerate:-1;:-_L_"111111er1L1e outcrops1:11-11Lr11p11 11'.in '."1a regionreg-1111'. 11'."of 111-511high rainfa'}l,1'1-1111111111. 111111and weathering1.1'e'LT'LLe11:1:T producespr1'11'.111L"L'11 richriL'h red-rLLL- brown11111-1111 soils1111111: that111211 support.1:L1-._.1r11;1:'t thickthiek natural11111111111 fL11'L:.1.tforest L1'.11'e1'cover and111111 after 1:11:111'11111clearing areL1re 1:11:1LL'11-iz2'e1'1extensively utilized11111111111 fort'L'Lr teatL-11 cultivation.e1-1L":'.i1'::1t''12.:111. TheT11L1113'1111'.:'1L1'L-drainage remains1'111'1111'111 highly111111111; immature11"1111111111e and'11'LL1 the riversr 11":1'1 consistLL11'L1..1' of.11 11er1e1:series L'It‘of rapidsr:1L'1111~L 1.1'L'L-rover lava-flowsl:11'11-fiL::1'-1'1'. or111' the harder better-cemented11etLe1'-L'e1':1e:1t1:d pyroclastic1311111.:1111111': 111111111.bands, with11111' alternate:11t1'1111te 'broad11r1'1111'1 1111:1111p1'swampy stretches.1trLLLhL1L TheT he presence11I'e1..er'1ee of11111:.tte1'better cementedeet11L-111ed L11-'I'11L111111epyroclastic material11'1111er1'LLi 111111and 11a figreaterltetttet' L1111LLr11rconcentration1.11.1LL1L'11'1111111'1L1.I11:L1.of .lava flows near 111Lthe 11111top 1'11of the.the volcanic1'1':-11::11"'11'L': piler111e 11:11.has resUlted1'e11111.eL in:1': 11.1an --.::'L'_11.1:..'::Ierosion 1'1-"arr:scarp :beinghezitg formed11.1r11'LeL'1 by the rapidrLLpi-Li remova'lre1111111111 L11of the less1L-H'11 LL11111111111tLL1consOlidated under-IJI'ILLLsr 1 1 lying13f'1'11155 materia'!.111111111111. This1.1111: irregu'larirreg'LIh-LI' 113111;}scarp borders1_'11_'11'11er.1' the TinderetT11111eret ForestF111'e11 Reserve,Re1er1e- and runs111111. 1.--at approximately'.111r1r1'1'11111111e11' 7,5007.51.111 1'EL'tfeet 1'11rfor '1L"-L'er11|several miles1':'I11e"-L 11111111south 1'11of Lessos.Le111211'1. The1he Ibasal111111.;1‘. 111L111'1ermember 1'11of thethe. volcanic'11-‘11L:L11"L-1L: sequence1L-11'11eI1L'L: is11'. seen.1'.L'L-I'; L1'1-ct'1f1."1t".-'1:"_overlying the :LeLi-irrtenh;sediments 1.11of Lower1.1:1'1'er Miocene‘1'1111Ler1e age north111:11'th 1.11of SonghorSortetwr atL1I a11 heightI"e1""' 1'11"of 4-1-1111}4,800 t'Lzet-feet while,'L1'1'.'ETL':- north:111r111 111'of the 11211111.scarp, in11. the11'1e vaHey1:111:1' 111of the Mokong31111111111:- riverr11'L'r it11 lies111:1; 111:'L-'L'.I1_L'directlly on111'. PrecambrianIJreLzL'Lrg1hI'11-11'. 14111111311211.111gneisses, at L1a heighthete't'L'. |- “111.111.11.11of 6,000 tLet.Tr111-'er.1.1r1efeet. Traversing east'L'~'.11'Lt tr11111from the1111': 1tLtteI'latter LXI-11.111111:exposure 1111:one t'e.1"111'11t'11'remains 1'111.';"LI'11:113_L-'on strictly 1:111:11—com- HI- para!lJle'111.1'1.L rockr1.:111L typest1'1-1e11 for 1111111Lsome 16111 miles,111i1e1-11'1'1L'rewhere 1111an a!ltitude1111111111.: of1711' 8,000:1. WIN feet1'1-151 has1'1-.11. been1111a'K- e11 attained.112 tL11r1eL; nu... ReconnaissanceH'1L11nne311111'1ee mapping11111pp1r1111L'11L'e11failed 1'11to rL-1-'L-'.11reveal '.11'111'any I".1'L='1_.11'1rmajor 111'111-"111111111stratigraphical 1'1-ror petrologicaJlr'11-.tr111L1-11L1 1111dis- .— tinction2111131111111 within11itl'11h the 2,000-foot2.1-1111111.111t sequence,Sequence. nor11111 wasL=L"-"'L1L 1111111-11211111'111-111'1111:1'.§j1re:1dan adequate widespread mar-111T111'11'1'11'111marker horizon located.311:111L1'J. A.31 .11-11'111'1ernumber L11of gener111general 11:111111trends were.1'ere. noted,11111e11- 111:111'e1'er.however. nIr—n.-I- The'1":1.e rocksr1'1L:1..1 11.11Lr1111r111"outcropping periphera:}lyeI'11Lr1111' are more1111.11'e widely'L1'iLtel' variahle'-L"L'11'111:‘.'11e from one1':-11: :.1111'1t'1"1eL"another than111.111 theme.those higher'1'11-_-._:11e1'1hin the sequehee.sequence. TheyTht.:jL-'11reare 1111111et111'1e1sometimes L111t111Lit1'L--'distinctly 51.1'L11111L-11stratified 111L111and include1111:111s mostrttL.:.1L't 1'11“of the finer-grainedt1t1et‘—gI'L'-11t1e11 members.1'11e11'.1_'1er11. The included111-:11111e1'1 fragmentsfragments. show1.111.111 wide111111;: variety1Ltr1etj. in5:1 size112i: and'.1. L1 L11-"L'.1LL'rcOlour index1111.1e'1L and theythe}; are usua'lly1111111111}; set111:?- in111 11-121.1p11'.'1tI:1.a copious fine-grainedt1tte—gt'1121'1e11 t'L111'L'-1L:L'1'1'.1.'1Ltuffaceous matrix.:1111trf1. TheI'he aggilomeratesagg1e.1111e111te5 LL111111111contain fragmentst"r:-11_.1111e'11t11 1.111of fossil11111.11 11.111111.wood, 11-11111:whose 1'1ee1111'e11eeoccurrence is11:. most11111111. frequent in111 theeethese 'lower11.11.1e1' Iite'"'members,t'1L11L t1'1'L.1-'..Ighthough they Lireare still1111 111111111found 11:1as high :11;as 7,0001'1111 feet. The CL'ILLrHL-1'.coarsest agglomerates--1--L-1L'-t"et.tte1. outcrop1111112111171 1111on the ridgesridge-111 111'1rti'1north ofL11 Kapchorua,K:1L'1-:.'111'.1:'1111. where'.1e1: boulders1111111111611 12 feetfeet in11'; diameterd1111'r1e-L':' Ltt'eare L111'Lp1Ll-eL1displayed 111in 11a new11:11 road1'1:1:'L'L1 L'IL'ttitig.cutting. The exposurese1;r.1111.11re.11 hereheI'L- preserveg1re1'e1'1'e L':'1'111L"I"11:eevidence 1.11of numerous1:1'111e1'e'111 e1L11211111'eexplosive 1:1-'-1:11."1.cycles, '.1-1'as included111L111-111e1'? t'1'1'LelI1-1e1111fragments within111111111 111':the largest311reL-1': bowlders17111111111111 21fare 'Lhe.'L'.them- selves1e; 1:1 second1e.'L"-'..'1:'1LL' and third LetiLf'LILi-J'Jgeneration pyroclastic171jLT'11'L':11'1't.-111'.'.1L1.111rocks. Lava flows111-1111: in the 'lower11::1'1eL" part111111 1'11of the '1e-".1_LIe11L".esequence 111'eare rare,rL'tI'e. 111111and of1.11 1111112!smaH latera'l1111121111 extent. The higher members111131": 111;:1'1 1‘11:of thet.'."1e sequence1L.'L1.1L:L"LL':: t'1'1L1tend 111to be1.1.: 1111.1remore massive,hie-11'1“; t't'tt-'.t:'emore L'.'L1'L'1e1e:".-t.coherent, '.LL'LLiand :1'1to L'11:11Li:1:'-consist 1.111of 1:71.111:11-olosely packedt1'.1L".~JL'L1 angular11:13:11111' fragments1111311113111; of1.11 :1a single1111111: rockr1'11:11.; type11.11: in1h L1a matrix111.11ri'.'1. 21111111111almost identical1L1etitiL:'L-11 1.1.1.111with that111111 1:11of 1111-11-111'e1'the lower members.tt'IL'zt'I'IherFL. OftenI1211111111 the.the r1"LL';'1tri.'~Lmatrix 11111.1and interstices1111er1't1ee11 1'1111'have .1211111-eL1allowed the passage1LL~L1.1"e L11of percolatingI1L1LL11LL111'1 111:-fluids11.1.11 11ndand the 111-:esize 111111and 1111:1111:shape 111'of the included1:1L'I'L'11e11' 1'1".tfrag- ments111::1t11 'L1rLare e111;1hemphasized1111;511:121 by.'.'-j1' marginal1'11111';_~'1I"LL:| LLLr1111IL~Ldeposits of11t'1'1'1'111ewhite zeolite.2'.e'L.":-hte. --- . 'JJJ 24_—1' TheT1'.C'. modeJJJJJL'JJ'J. ofJJJI originJJrJIJ-JJIJ'J ofLJJI J.J'JJJ.J.'-'some LJJof the'.".JL- fragmenta'lJIJLLJJJJ'JJJJ'JJLJI rocks1031-1“. occurring-..J.'_'.J.'.J.J.JJ“JJJJ—' J'LJ-:11".high in11‘. the'JJ'JJ.'-. volcanic'-.'J:1CJJ:'J:. pile[.‘JJiLz. is1'.-J; C1111IJCJJJ1J.difficu~t toJJJ state.J'JJLJ-JJ: C'LLJLJJ.categorica'lly,JJJJLLJJ1JJ JJJJJLJgJ'Jthough mostJ'J‘JJJJJJ L'JJLJ.are 1JJ11I~‘Jtuffs LLJJJJand LJJJJJJJ'JJJJLJJ'LJJLJ-Jagglomerates 'JLJrJ'JJLJC'.formed from1II'CJI'J"! faiIilyJI'ILJJJ'1JJJ 1“.JJJJ'JLJgEJJJitLJ-Jhomogeneous pyroclasticJJJJJJ'LJL' !.'J.'-'J11C JJJLJ.JL:J“JLJ1.materia'l, 616421dejected LJJJC1and .'"JJ'J'JP.compactedLJCJ- L1 while.JJJJ J-JLJJstill LLJat JJJJL'LJJ.high - - . - ' ' J . .‘~ -. . . '. ---'- temperatures.JL'J“J:‘JCJJ'L'JJJJJ'C-JJ. .'JJ.JJ';“:J.JSome sma'llerJJJ'JJLILLJ.“ outcropsC'J'..JJJ.'"-‘J?JJ'~ mayJTLJB' we11"-'J'L"1. beJ‘JL' .J:higWy'J1f'J' contaminatedCJJJJJJ. JJJJJJ .J'JJ. lava-flows,ILJ'-. 1.1.‘i.'-..1II‘r‘J"J. whichJJ. .JJJ..J. were'-I.'ILI'{.?'1I_I'.‘JI.1..III.IJ.JJ.I.I..'.extruded I' JJJ“on to‘ - ~..'..".-....surfaces .JJof unconsolidatedJ..'.'.J ' ... JLJ:'J.._.Jn. fragments-.|-'.;.'. n.-- :. 1.‘--. .of- similar~ -J.-|. JI 1J.J -- .Jcomposition,_ll J--J. '- '-' .J ' L.and'. pickedI,I“JIJJ.'1.J.JJJ up.LLJ .-a high1JJJ.J.JJ F'-proportionJ'LJ-DC. JLLI-LJ.J ofJ_.JJ "xenoliths"..J..J_-J:.JJJJ J-. . Other1.‘-JILL; texturesJL'.!.L.'1L"* *J.:_J-..J.JL.JJLsuggest the1.“.J. fracturingE.-....-..1J.:‘JJi_ ....JJ.and ' .J . J:.J.. , _ _. ', . J. .- re-cementing.“L-J L-JJJL-JJJJJJJJ J'Jof JJL-JJLJJ.partly L'JJJJconsolidated..JJ.J.JLJJ-'JJ :lavas,.JJ.JJJ. as.. ai possibleJTJJJr-JJJ- LJ J.JmodeJCJJ. .J.of .‘J‘-.2111-origin. A.-I"C J‘J‘JL:;J.}T‘major minera'logicalT‘JLIJ C’JJCJ'TJC... C31JLJJ‘LL'LI-.J_“..JJ-'L.-J.characteristic IJJJ'JI-Z.J'--T|.LJ1-Jthroughout this11—11“ pyroclasticFj-J'-."-.1.1J~1-._. suite,J..l...J:‘. and-.|.:'.-. the:.L lavas'J within'J'-.JJJ'.JJJ theJIJC- pi1e,.“JJJJ.J. isI": theJJJC- preponderanceprC-JJJ.'JJ“JL1J:J'LJ.JJCE ofJ'.'JJ nephelineJJJLJLJ LIr amongL'_.":'.JJJ'.2 theitJL‘; leucocraticJJL:J_JC:J:JC'J'.-_JJ'_.': JJ'JJJTJL-J'LL1--.minerals, =.JJ'.J:.".often .J1JL':rL-L'1altered andLJJJLJ part-replacedparL-J'C-LJ..1L'JC-:'J1 L-_-:J'"Iand .*J._'|l'"J‘.-EI[1II1"11:'Jsometimes ELCCJ'f-l'i'ili'T-‘CIJ‘J1CTCI.accompanied 1“}:by meIiIiteJ'."JJ_'-1IJI.JJJ_- JJ-ror 11‘1“}.1C1EJII.felspar. The1I1'JL: 1‘.J.="'TI‘.'L11normal IJJ'LI'IIIILELj TJIEJJ'JTJJJ- ferromagnesianJItrrCJJJJLLgJJEJJJLLJJ mineral1111t51111 is15: aegirine-augite,L'J':2EJ'JJJJ:'-a ELLJJJ11J'... JJJJC-JJoften as:JJ. part-resorbed,[.JLLJ'J.-JL'J.~LJJJIJJLC1 highlyJJJJLJJJJJJ zoned pheno- L_".J“J.-'r-JJ.-:_.crysts, whilleJJJJ'1J11J2J_JLJJ'J'.J.C1rLLieuhedrall sphenehlt'i'IJ-L-. andJJJ.1 fine-grained‘IJI'IIJ"JJ:-J:EJ'El'JJJJfiJ;1 ironJJ'-:J.'J JJJ'L':ore LJJ'J:are usuallyL..‘-J'L1'.-_11JJ-' present.“.JJL..~.'.'.'.J". (-IL'Jl-L'JJJ;Calcite .JJJLJand JJ.L--..'J11.'.r':zeolite UCJCL'J‘J‘occur L'J;almost'JJJJ'JJJL universaUyLJ'JJJ'J 2:r-~;=.!I.J.' .'_J~.as LL'CCit“---J~'.'JI"_‘J'accessory J'J'J1J'JC'TLJEJ.mineralls. T,,1...... _...... -_.J. _:J'. ..._.._...... _L _. ...;.'.,.-.. I“.-. -.._‘T‘..,J_ _. . -.|-...-.-.,. Agglomerates-"'I.L:.:'.:1:'..‘..1.JJ.IJLi'.LI1'J .JJ.J.J.-and LLJLJJJ.tuffs, [-L_'J:.J:.l-JJ.'J_J.tentatively .1*J~.-IJJ.-L':CLassumed 1.!to -..JJJ_.-_.'J:JLLL:originate J.J.JLJ.from theLJJL. TinderetIz'1.JL..rJ.J volcanic'~-. ...-J ... C'LJJJJJL':.J.'.centres, LJC'L'LJroccur ZEL'J'.as farJILJJ' LJJJLJJJ'IZafield LJ-Jas Ka:psaret1LL'JJJ"; .J.-‘J Forest.t'JeJ...--\.'J1JJ:AtI. the.._ waterfaH"J'J-.'LJ‘-.J';-.J":'.': 1 J J.‘-.1"_L-J'LJwhere theJ1'JJ.-. Kipkarren1*. J JL...J- "J riverJ“JIJ.-'J':r passespL-iJ-JJJLJJ. CJJ'JIoff theJ1JJ': lava1.'L'J-"Ei JJJJon toJJJ J.JL:.the BasementBLJIJ-JLJJJJLJJJJ SystemS}-'J-J1L"J‘J‘. CLJJ-LriJJz-JLJJJgneisses aLL JJJJthinJJ JJJJJiJ'J'CJJJJJJJintervening layer1LJj..'L-J_' JJJIof pyroolastic.J_J.JJ_JCJLJ.-.JJJ- J.J-.LJL-rJ-.JJ.material k1'..-L._'JI“-.occurs, LLT1LI.and J.JC.-.JJ..JJJJ:1occasional hlocks-.J|J.JC.J.-. ...JJof JJ_-..-1tuff L-JrC-are preserved.JJLJJLJJCd ..Jin J.JJ..the 1.-.-J.JJJ.base LJ.of [1‘16the phonoliteD1JL‘JJ‘JC'J1JJJ; .1LJJJ.flow.. - This'T'JJJJJ. indicates1J'J|._-.'-....'I.'JI..‘.‘J-..._.. .. J1JLLLthat.. the.J._..J..._' J'L'LJJIJJr-JJearliest_. phondliteDIJ'I.=1.-I-_.-.-11.LI. ., .'.." -. .TJ.-J.J-.~.flow was,JJLLJJ.. UFJ..-.-._L1J:J..preceded.J by''J‘J_-_-._ a periodDEJ'JICJd CJJIof fieruptionrLJJ‘TJiJCJTJ ofJJ.‘ fragmenta'l1I1ILJ'._'._'ITI'.II:J_‘L—11:J1 rocksJ'-:."._Z1--'.'- thatJJ'JL-LJ J'J.'.J.“J'J-_-J.'formed .1a '..I"J.'nthin mantleJ"':'—'.“J:.‘r'- overCJJLJ muchJ"'.;-".I'J of:2"J theJi'J' CCHJJ'JIJ‘}'.J;1C1L'.countryside. U‘JJJ:One {1'12113mile JL'LJJ'Jieast JJJIof (IJJL-JJ'JLJ-JJ'.L'J_Chemuswa, L'JT.at L1JL:the 'J'-.J':J~JL'.-J.'J‘Jwestern -L-J.'JJ'L-J“'JJJj-.'extremity .JJof ':1':-'-the p1';J'~:-J_JIJJLJ-:.phonolites, JJJLJJ'L-there LJ."-.are :7“.exposuresD_--'JJ.1JJ-.'J. -:.J1of pre-phonolitepr: :JJJJJJ.J..J.JJL.' pyroclasticJ'JJ.rL:.1J.JJJ...... :CJL'J.rocks with'-'-.1|Ii .Ja wide1 !'-"'.JI.._. varietyJ--"lJ_-..‘t I'. L11of 111.33fragment1'; J'. ‘Jlr'IL'.size, I‘III.I.IJ_some 5.3-1 T. i.. -. ._-.T. ':.....'...... 1....-l.r._.,.1 .',...... 2... .._., .J'.. J‘" i '...,...g'... J. __. of the-1.I1~I:'__I' largerJI-I-I._-' J piecesP_CLL-LI‘- -.-L.:l1'_being I...".__.'~1._I.Jderived from'..-.-.J| pre-existingTIN-LI“ 1.3.. ~“.11: ..': JL.L'_._L__.-..-1__II1'._I'agglomerates.'I'I1.'-.—.II."J. Usually'L "J-..-.....- theyIILJ LL;'—--are greenishJLL.J $.11 rocksJ'J‘IC1JLFJI with'JJJJ'L'J'J. fragmentsJJLJCJJJCJJH LJJIof L'Jl.“JJ'.-LJJ.about :.'::JL'_-one centimetre.'LJJJJ _J“.JJ.'JJL JJJLdiameter,-JL-J'. JLJset JJCJLJJ'JLLJJ.sparsely in12‘! LLa fine-1171:- grained,:JJ'JJJJJEd. highlyJJJJ'I_J1JIJ__.-' CJJICLLJ'CJ'JLJJLcaJIcareous JJJ'JJLJJJL1HJLLJJJJ',groundmass. Much1\--'1JJJ.'1J fossilJIJ_J-'~L'~;JI1 woodJJJ..-JJJ'JJ;1 isJJ. presentprc.~;.-'._-J'JJ L'JJJLJand 'JJJ'JJIJJJIJJwithin theJJJJ; ..JICJJL—JLJJJ1'JLJLJcalcite-replaced J.'.JLJJJ.JJ'outer .JJ’J'JsheNC-11 C.JJIIof JJLJrJJCsome *D-‘323JTIJJJE‘JJC.1JIJJ."specimens the -.J.LJJJC11IIJ1_JJ'J.J*wood-fibres remainrJJJ“J'."JJ:J J-JJJJJJZeJ'LzJLJ.unalltered. I1I1'.'I-This L.:'~.'J'J-.JJ'.-'.J.J'LJexposure has1"..1'LI1I'. ,beenJ.J.L'-.J'.':.J'J LET-..JJlLJJIJL-LJexploited L"J.J.J-.'-.J'.-~:'-.'J.-11.'.extensively, JJLJJbut unsystematicaUy,J_JJJ'-JJ.'--J'Jc:'J“.JLJ.JJJ.':'_=-11J.'. JJJL'for building-stone.1TJJ.JJEJ'-'.‘JJ'-"'-J'-‘-.J.'J!'JJ.' J.._J_':L'JJ'-L-Coarse-grained_gr'.L'.'.JJ-.-L1 JLJJ'IJIJJ'.tuffs, -L'.-.Jr.JLJJJJ£JJ_J-.Jcontaining 'biotiteI!‘JJI.‘-111.J.‘. J1JJ1~LLJ-flakes J'JJJL-one CCJ‘JIJTTJEJJ‘J‘:centimetre J~LJ_i.J..-'J.“L-square and-'-J“.L1 augiteJ‘JJ' .'J'j..'.-LJJ1:-.crystals JIIJJ.'r':five JJJJJIiJJJL-Lres.millimetres :long,JJJJJE. J'JJJJCtrJJpoutcrop 1J'.J!.}'Jboth JJJJJ'J'J':north '.'-JJL'1and J.JJJJJ;JJsouth JJJIof KJJJJ-JJJL'JnJKilibwoni ;:Jin JI-JJ':the EJJJJJ'L'J'lower groundi__'_|"L_‘.Jll.J‘IJ'.1 JJL'JJJJJ-'L":LJJJbetween 11'JLJ.the phono'liteJ'JJ'JJTJJJJJ1JIJJ'; FELJT‘J‘!scarp L-JJ'.C1and J1JL-the 1Ji1.hiNsJ. J_JJIof BasementBJlHCEJJLI 1‘.-1 SJJJJJLJJJJSystem J-JJLLJiJJJgneiss JLJto JE'JJ:the west.'-.'-.'J.-J'.J_ T'J'JLJThe level1J::JJJ:'1 is1:4. LJJ'JIJ'on1y J11;21JJ1'_-.'slightly I1‘l1'_.1__'1‘JJ_"J‘higher 11‘.ethan thatJJ'JLJJ LJ'JIof J'JJEthe :-'J.L1_i-.'JE:J'.I.“J_J_.-.Jadjoining KingwalRing-2.21 .'-_'LJ‘.J;'1and KiptergesKJJ'JJLJJ'LLL'J. E'J C1" JJ'.J.'L'JJJJ._CJ-'..swamps. Thus1I1JLJ-~. JJit is1J.. possiblepJJaLihlL- thatJJJLLJ LLa LJ'JrJJJJLJLg-J'LJ'JJJL-considerable J'JJJ'LJ'J-L."J-.-.J.:Jthickness JJ]of pyroclastic' I rocks is preserved beneath[‘JE'J‘JCEJI1'J 111-1211111111.the mantleJ: JJJIof 'black-cotton1J1LL'L'. L-L'JJJ.'.J.J.'J J . 1 --. -. .- 1- -. “.1 — - 4J1 -.-- .' I I|._ 1 'L -. ..- _ - EXExposures' I‘--I'LII‘ [-1threeIL'J— milesIII 1“ south-westI"-'.._I.‘.1 III"--I" '-I1I.of bx'rIII'HL‘IIIC'J.Kibebet have- l1l‘h been..IIII..I_I I"sporadicallyfi'LII J..I.J1J..-: I'- .._quarried"1 ".._. +"for —\|-:1' ‘ '-'1 J'r_._‘.-I".J. I'' ' -. J... :'|_ "-'' ' ""-. I .- .' . . 'fi '7'.'I. .'I ':JI| .. I '-I' ' J. '. '_."1 .'-1'' II- _J- . ' "I. .. _-' - building-stone..-_allIL]4I1-IILL 1.'. .1J_. The. .'J.. yetiowish1 hill‘]l|"d|\!-: II.'I-JI.II-..-JrI-..'..-outcrop £Ilk-.--_lJ-.JL”'-includes :'la wideI“':L;';. variety'IJ'_1.1II- I._.. '- Lof, rock.'-. In... typesJ -J-'.._.I"- in.I frag-JJ... _ .J.--.J:J.J'_-'.ments upL..J. ...to ..'...one..._. JJJL..Jinch'_ '-,. .JJ.'in J1..JJJ.-._-...diameter,.',...._..,.- r...set _'_linJ.J ,a- JJJJJJ=_buff :'.._.J,.highlyJJLJJ;;-- -_1.calcareous-._. _. --.:J matrix containing LJJJ'JJC-L1J‘LJI.euhedral :.JJ.JgiJ'JJJ-;:-LJLJgiT.LL_1JJaegirine-augites. In J1‘JJIJ'Jthin ..J'J'J:C'JIJCJJJsection 1.1—1(34/234) it is seen that the pyroxenes present .. ..J .J. ._...... J ...... J _ -‘ . ..'. _ . .. . ,. . l ._ . .._ include_-:I1J.11.-_'.C JUN-1-2:zoned and.J'.-1L1 unzonedLLL'1._JTJ._J.I1J._.J.J .J.aegirine-augite,21.1 111:._‘.-. L11{.:_._‘. ._-.and" _1 aegirine-augite.LJ: "1.l".;,_'- , 1 '-_‘ withJ. 1. "J .J'JL'augiteL_' J.._cores.‘J ‘- Pseudomorphs::J J-J._'1.J_. .1.IIIJ1.1I-I—11I 1‘.-“11‘ '- after.'TII... euhedra'l“..._-L.I-r--_1 nepheline- 1LL_ fi-l '._|L1 1',. .11‘».areJ presentIv1rJ._...HI '11- ...andI —IC TIfelspars._ I I-u—,LJ.J-- with-'-.J.| ....carlsu—IH badi .-JJ twin-I L. 1.,“— L'- ”r..- .. L .. -. . '. .. - J .. ...J-|-.J. -.. ., .— ...-. .l L. . .. ,. .' -. LL, . ..|. ,. ning.1.J._. Fragments-1IL_I ' 1 ‘J ofJ._'1 phonolite1|.-. J.i.._ and1.1. nepheliniteLL-.|.._2 IL. are... present,I ‘J' ' but._ asL‘- a._' wholeJJ I.'_L theJ_|rock-.’JL ha:s.._.J the-J--'J..1'..'._.I'J1-1J.-"J_JJJ'1composition-. —. . .-.- v-I . of.JJ a.J melanocraticJ.-J|J..JLJ.- .. . . phonolite.L.JJ..J.-.J'- -. -1 .J.-. SpecimensHLJLJ-L'JJJJCJJJJ 34/247,3111'.- 3-5334/27227': L'JJJJ'Jand 34337-11134/350 ;'J-.-“J';are .'-J11all JJJLLJJ‘JJ'JIC-JJ'.examples ofJ'_J:I J1JJT.the more' '.'_'J.JJJL compac,t'-..I.'-"I.I1II-'LI'-I.IL'I11 L:'.JL_J_and uniform.JJ'JLJIJ_J.“J‘-.J upperLJJJJJ-L'J' part'.J.-:JJ'J ofJJJI theJJ.:.J agglomerates,22-21..JJ':'J-LJ".'_JT_LJ.J.. thoughJEJLJLJJ21“: inJI.“J each2.1.311 case.';J~'_J theJJ'JJ2 modeJIJ'JJ.JJ:'.IC: of.JJ origin-."-.“JJ.JJI.“J of.JJI theLJJL' rockJ'...'I isIn inJJJ someJ..J'J.. LJ-.'J.J"Jdoubt. TheyI1 may.rJLJJ be1J. recementedJ‘...J'J" LJ fragmented:I'.-._JJJ:' ..JLJ 1L-J.J'.J..-lavas. Specimen.I'JI~.L'LJ.J:JJJLJ..". 34/272,PI 27:. fromJIrLJJJ'J near.J'.-J'JL-‘Jz' Singhalo'J-JJJJgJJLJJLJ sawmill,:Ji..J'--.'-.':“:":JII;1. isJJJ a homogeneoushJJJtJ-LJgC-JJ-LJLJJJ-J. fine-grained1II'.‘:‘JJ."-J:‘_I‘E'JJJ‘-J_"L1 C'1:"-.J“I'JLdark rock"._‘.J._‘1-; con-L“.‘.".'.- spicuous.JJJ“J'JJ'.'JJL‘JLJ-. onlyJJJJ1J' for:IJJJ' itsJi.:~. large12-.c nephelineJ'JJEJ‘J1JLL'IL1JJJ.‘ crystalsC'J'JJ'JJJL-JIJJJ andLJJJLJ occasionalJJCJLJLJ-Ji.:JJ'_.-L_I :~.JtJ.JI21small ferromagnesrianJI-.'-J.'.“;J:'J'J:.'.J._JJJ-.J.SJ:J'.J p;:-- ___.-;_| 25 prisms. The fragmental.1". 11:. nature111111112 2-1of 1112the 11121;.rock 11';is readily121111211 noted1121211 in111 2.111111111111211.exposures, 1'11'1511owing to the i preferential1"1:'"L'i:1._'"IL'_iIi.iE_' weathering11211111211111:- 2-1'of 1112the matrix,11111.!1'1'11. 111:1but in1:1 hand-specimen1.1111111- 11111-1211.--12-11 i,s'.1; 1'.-11121111;barely 211112-211discernible.1111L .111In thin1111::- 112211112:section theL rock1'-L1'L':.~'L is1'.-L found111111111 11':to be."12 21211221211composed 11:"of 111-11112111111numerous 11111211smaN zoned111111211 1111'-aegirine- - , 111-1:11.112augite 21111511112.crystals, large11111-2 pseudomorphs111-.LL-11111111111 .. 111'121after 21111211121euhedral I.LL}1LL'rnephelines '211111and oCicasional1122.;1511‘11111-1 L1'.1euhedral sphenes,1.111121112' _- :1121set 111in :12an 11121111111123isotropic groundmass.111111-111LL-11; crowded2:"-'L1;1;2'L1L'L with1.1111111. aegirine-augite31111-1212 prisms.11111-11111;- '1'112The 2211111111;composition11211 is,11;. therefore,111122211112. melanephelinitrc.1112 1111121121 21311111112L m-——-—-—u—-u-—- .1 _I .-Specimen 34/247,1".) -?- 1.121111from :121'211seven 211111;miles 2:11;:east 111'of Les&os,1.211111111. is1:1; a similar111'-'1'. 11111 112312111211fragmented 111211..rock, but11.11: is11111111211111altered 211:1"and has11111111112111.12211'introduced 221111L2zeolite 111111and calcite.21172112. 1112The composition21111111111111.1122 1:1'1112of the 111111111;matrix is1:1 very2:3: similar1111111111. to111 thatH111; of1711' 1112the 11112111111221included 11112111211111fragments and221:1 boundaries111-1111111111121; 11.1Lare difficult11111121111 to1:: 11132211.";discern. T112The larger111153121“ crystalsL‘1L1;1'11; 2.12are waxy13111111111 yellow11321111111” 11211112111121;-nephelines, smaller:'-1111L11121' moreI'11L1I'2 common2111111111111 1122111112—11I-12:12:-'aegirine-augites andL1-LI1L1' iron11'1111. 11121;.ores, 111111and oc'casional11221111112111! sphenes.11111211211. '111211'111'11-151L1L11112The part-isotropic groundmass21111111171111.2111; {'11:of :11111'12some 11112—frag- ments111-211.11; 11111'1'121';carries 111111121111numerous11; 111111111small laths111111111 1.'1Iof felspar,1211;111:11- 211111111111-giving a 111121111112trachytic texture1'11112 11111:!and 11a resulting12511111112- 21111'11111111'11211composition 111'of :1a 91111111111112phonolitic 1112111melanepheIinite.12111121111112. -- -I-- '11- "'1'I "'i"' -r '- II'r.1.-'I-.|-'I r....--—---.1-.—-u—u—u—-u——--u-—-—u—u—----- .' - . 'I: - - '1' 'I -"-- "I A:1. rock.;_1L.-L consisting2L111:;.:;11.1;1 of-.11 larger1,-1.3“ closely~packed21L1:;211.--11L;LL;2L' angular111121-1111: fragments11112111211“. of11;: phonolitic21.1.1111; J nephelinitecomposition,1122111211 - 111-L1. 21111'1111121111111111;is 21111121211exposed four111111: miles1111121; north11111111 111'of Nabkoi.1'111'111-1'1L111. The1'112 111-1:111:11matrix isL1; 111'only1'1; .;' '. 1. 1 . '. ;‘----I L. LL. -. ' . . r L ‘ L 1 - slightly1115:1111} paler1.311191 than1112111 the1111'- inclusions11“=L."LL:;1131-.1; but'L-‘L-L’E isi1; highly1115311111 replacedL2_.'-‘.-1L1L2L1L1 by11}.- whte1L'1'."|;-: zeolites.£2.1"11'111LL111. 1211:11-1-1-‘1'2L1Corroded nephelines11211112111121; 111111and rare11112 felspars,1211;112:11- 111111and zeolitic1521111112 patches111112112. after1111-11 nepheline,1211112111112. 21111111111112constitute the-112 leuco-12 :1211— cratic2.12112 minerals.1111121111112 '1' (3)1"."11 '1'21111'11111'1'TERTIARY LAVAS1...-';';.-'11L:;' (a)1'L11 1 Classification{-'1-1.111111.".1'1"L'L'11'1'11.1: “whim—L The111-2 lavasI-L11;"-1.:1 in.111. 1112the 1.1.1211area 111111-111.-show 1-1.a wide11.1112 range11111122 in'111 21.111111111111221.composition. 11121.1They 211:1:1111consist 111'of 1112the plateau11111121111 phonolites,111-1121111111211. 1111-1and 11a 2.111112111111111gradational 1121:1111;series 1111'of 211111'11121211'1111211111'characteristically 1111:1112basic 111111and under-21111214 11111111111211saturated 1L'rock21L 11.11121;types 1"111111'1from '11111121'21.Tinderet. '1'11L2The 1111111211111."difficulty 2111122211112of accurate 2111111111121111'1111classification 11';is 21111111112211enhanced by1111' the1112 fine-grained11;-21:11 1111 nature11111112 of1211' the1112 'groundmass.2: I..-. "1121111111211”; 111in many1111111}: cases,2111-121";- when11-‘1121'1 it1'1 is11; impossible1"1'.-1.[:1:1511_§E_~1_1.;-;_- to1;; L'1L1L21'11L11112determine with11;-1111 2Lcertainty'1'-L1: 11111.1 L112the 11presence'1'-1221122 111'or 111-1521122absence 11L"of 1.'-1121221111111:diagnostic 11111112111111”:-minerals, 11Li'121'other 1111111than 1111:the phenocrysts.1111L1111'L1211111;111-1111In examples1LL111111L1; 111.1111with part-iso,tropic:11'1~1':;111;'111112 2.1211112111121111.groundmass 1'1-it is1.-'; 11111112111112;sometimes 11111121111difficult ta11'.- distingui,shL...'1..:1.i- '1-[1i'_"_.:':'1li11'11'.1: between}1|:1"1II'I'IL.1L-'In.1 ."- LL.-.1 21L1.;1L1'1'111Lanalcime.- '11"..-. Land.i'td-- glass..1;-L112.""'-i" " " '. -- n' .1 -. -. .— -- -.LJ .'.- ' -. 1. ' ' ‘- . F." 'l .. .. ' ' - . The1.113.191:types 1L1Iof I1i-1'1L'EJLlava presentjIL'L'f1:L'.:I1 LJLI'c'L'are 111111111111indicated'1'LLLI -L;Iin 1:11...the ILL-11111.:table 172-11%.below. 111111.3[1When 1.111.;the total1611111 ferro-11;-'1'11'1'1- I I --;. magnesian11.111211111111111 111111211111;minerals 211221-exceed111 1'11:the 1111111totalleucocratic12.1-2L1-L'11111'12 minerals11111.121'11151111in 1111111211111amount 1112the prefix1112111; "1112111"mela" is1:1 employed2111111111211 in1.11 the1112 case221-12 of111' the1112. phonolitic21121111111112 and1.1111 nephelinitic112111121111111'2 types,11111-1211 2152-1.e.g. melanephelinite,11121122111122.1112. phonolitic11112111111112 meIanephelinite.11.12121122112'11'11112. "111111212Where 2111111121112distinctive hut1.11.11 11211—1112211111111'2non-diagnostic 11111112111111;minerals 112L211.occur, 111'or :1-a second1122111111 felspathold121111111111111111 1.1;is present1112112111. 111in 22112111111212subordinate 111111111111-amount, 1112the 111111125;names 211'2al'e 1111111111221modified 1111-“by 1112the inserti'on1111111111111 'Of111" the1112 mineral11111121111 name11111112 as11:11 11a prefix,111211.112 2.11e.g. melanite111211111112 22111121111112.nephelinite, 11111111211112analcime 11:21:1111Lbasanite,""I melilite1112-111112 11.121.11—112p1-121111112-meIa-nephelinite. CLASSIFICATION[TL-1.11211111111111111 111'OF '1111-THE TI=.1'-1L'1'11.111;'TERTIARY LAVAS11.12.1111; 111'OF '1112THE 1 Leucocratic1-2221121'11112 Minerals1111111211111; FerromagnesianF21'12111flg11251211 Minerals71111112111111; Rock[1111211 Name7111-11112- - -- — — I .._._ I__-- - Clino-(1111111;- Felspar211-11-1111' 13215112111212] 11111111112112 1'111111-11'12 1111111111112 1 Felspathoi~1 pyroxene I Olivine Melilite I "11111111111112 I Alkali15.111111 . .. i Nepheline11121111211112 xI11; — — iPhonolite I 171-12111 _1 3'111111111111'112 Alkali1"1L]1~L11"L1' {1;L1111-11'L'11'11L—(subordin- I “1121111L1LL-Nepheline X i —- Nephelinite111'2111'1211'11112 ate1112 11111221111.amount). I - I (Mela-) rhOnOH'"3 Nephelinite11211112111122 — 1112111121 1'112 X.‘11 —- I r, (>50%)[5113'31 I 111-1211111112Melilitite .. I ——- I Nepheline X'1'111' I X (>501" 51111-111%) B1152111'12 . 1'1112'11211152 1.111111- 1121111211112 X'11 I X Basanite.. Plagioclase(sub- I Analcime i I L11'1L1i 1111.12 1111111111111 1111' I I ordinate amount) I Nepheline5121111211112or ! I . ""11” 26-_"-1. 1515151(b) PlateauPli5-15115555t1'55'5-1'151' 15—515111'111111'51'1'5-1'1'1Phonolites .- (i)1 15 '1 Distribution1I'_1'I1='.1.-'1'1'5.'5.I11I11=511.=1 Plateau1111111111111 phan'Olites1'.-11111111111111 111''Of .11111'11121151111111'1'1.Shackle tan's Uasin[.'1-11.1511 (51151111111Gishu 51'111'11111'115111Phan'Olite (Shackletan,11'55111'111111'111'1111'1.'.=11'11.1945, p._1_1. 6) 1:111'1'1caver 14.1:11'11'same 1111111111111'One-third 111"'Of 1111:the 111111area mapped.11111313111111. T1111The lavas11111111.; dip1111'. 11111-11111gently 1111ta 11111.the 1.11.111west and it is1:111thaught1-71'111.1_'_1'1-1 111'1-‘11that .their151111.15? 111111111111:s'Ource 1111111.was samewhere2111111111111:.11' 1151111111beyand 1111'the 11111111'1'1'1eastern margin:‘1':1=:1g111 of1115 1111'the 11:11-area. Tw'O'1'-11.11 maj'Or111111111 flaws15111-11111 are1111.1 distinguished,111111111411'11111'1'11.111'1:11and the1111' high11111111. _'.111-11111115gr'Ound t'O7.11 the7.111- east1111: may1:111}. represent1'1.'11:'1.-11':'.'. 11113111111311.subsequent 1111111111.flaws, 1111111111g11althaugh 1111no 111111111field 11111111111111.1111distincti'On 1111111111cauld 111'.be 1111.111111-discavered=1:.11 111311191between'11'11 1111111111111"?expasures, 111.111and 1111na 11111115111111;'Obviaus t'Opographic1111111131'11111‘1151'1 15'1'1111111'21’1features .1231111'111'11‘111111representing margins1111111111111 1115'Of 15111111111:flaws were'1'1:_'1'"1' 113.1111-1r11v111'5'Observed, 1'11-11'1111!except 11'11far '.1a few111111 miles11111111: 1.1111111sauth 1111''OfKaptagatK111111331 '5111511111.Station. 111In 11111the 1111111area 111t'O11113the narth11.11111 '11a 511'1'11-151.1.'-.'.5lava-flaw .'1-11.12.has 1.1'1'11'1been 1111113111111mapped by1111' 311111151111:Sanders 11131that 151'.is 13551151111111earlier 111111:than 1'.-111'."th'Ose 11121121151111recagnized 11:11'1'11sauth .'11''Of E..1111r1='.Eldoret. 1 1. a _‘ _‘ .- __1 .- .... I“; ,1-1. , 1— 1""' ,_1 I1'5_1 1._. ... .r'i. '-_l" '11'1Where11'15'1it 111:1'11111'Occurs 11'.-in 11'1'the 11"1'1'111:11present 1:11:11area it11 11111has been included.l' with5 the 11'1'1'1'11'11'lawer -:':-15'Of‘_'11'the 1'111'11twa 1111-1i1'.main 1111115111.flaws 1151113111111=already 1111111111111'1'1.mentianed. The1111' laweri..1'.'.1'.r' .11'Of 1111-the tw'O=1'-.1.1'I phanalites11:11111'.1_1..:1'-1. distinguished1'.1~.1=.'.1':'.111.~1'.'11::- is1:11 a:1 sparsely1111111112}; porphyritic1'.':'1.1.".j-.1"_:1' lava,111'11I. and11111: '11".-1'the upper1111111111 1'1'11'1111111'11'1:oantains 1111L1111111111abundant large11111111 nephelines111111111111111'11' 111111and 11.111.11.111.glassy 11'..1~}1-111'felspar 111111'111-1:T'-.11'1.~1.phen'Ocrysts, 1:11.111};easily f distinguished111211111111115111111 in111 hand-specimen.11111111-.1111111111'111111. The1111' basal11111.11 flow11111111 farms111111111 the1111.1 greatest1111111111.!L part111111 'Of1.1: the1111- 11".flat I 1| '21 land51111111 'Of111 the1111' plateau,1111111111. while11111111: the15:11- later1111111' flaw111111 in'._". the1511' east1".=1.=-.E and1111-11 narth1'.-1'11'11'1 'Overlies1111'111111'1 it15 farming151.11. -"1 a pron'Ounced11111111311111.1211 near-c'Ontinu'Ous111:1:1-11I1111111.111'1 erasi'On111111.111: scarp1111-1111I at11'. the1:.1 juncti'On.11.11.11.111. Where115111111: the1111' later1.11.-'- lava1--!.- spreads111-11111111. t'O1:11 the1111. west1111. in11 the1.11. middle1111111111. 'Of11. the11.11. 1-1area..'.1 it:1 is.~. at.-.1 a.1 similar,1111.....11. 'Or111 even11.11 l'Ower!-11-1111'. level.11-11 than1:1:111 the1111' earlier1.'.:11'|5:1'.1- member1'1'.1.-:1:1".-1'.' fl'Oaring1111111111; the1111' plateau[1.1111111'11Li t'O11I the1111'. narth,11111'1111 'Owing1.111.111; t'O11'}: the1111' fact1111". that111.111 as11.1 it1'1 221’ 11,1 spread111111111] ta111 the[1:11 51:1515'115west it'_51 '15"5'1'55'OverlappedT1 the,_1 1'1-11'1111earlier flaw,1'.-111.1. 1111111511;coming t'O 1':-~11rest '._111an Basement11:-11~'.;"1'.-'111 '51_'.'-.1_'11System gneisses,'_.':".1:E51_'1.1:.'1'1=.. and1111111 in111 places11:11:11 Mi'Ocene."1'11.'.11'1'1"1-115 sediments.11:15:11-1'1'1111'. Bath111-11111 flaws1'.-1111.1. tend11'11'11 t'O.11. terminate.' 111-151111 1' with11.51". distinct1113121111 scarps111111111 'On1'11'. the111: west111-211'. 11111111111.except, as:11. in511 the1111' regian1111111111111 'Of1115 Chemuswa,1'1'551':11':'11'1.'.~_1"-.1.' :'.-.._ where'11."111':11'5111:the flaw1515.111'15z."11'15:'11'1'1=.feathers 'Out1:1:1-' against1111111511511 a'1': ridge1'1151g1: 'Of1115 1111111111111gneiss, in111 this11111; case1'11111' an1111 upstanding11111111111 1111;; .1p11r~pur fram15"11111'1 the1111' Algabbyet.-"'1.1g1=11111}1'1'1. hill1'.-1151 mass.11111.11:- A daub1'.‘=-.'.'.I'.11111CIe feature,151'1'1'1111'". where1.11'1'11'1'1' upper1:1'1'111'1' and1=..".-11 l'Ower1111'1'11'11' scarps111'11'1'1'._. are:1_1'1' nearly'11:.111'11' caincident,11'1'11111'1'151111'11'1. n'Orth11111111 'Of1'1-15 the'111' .. '1 '._ . 1 . 11. ._ |.. .' “"11“ —-1 -1- .1 - .._. Kingwal11551::1'1'1111 swamp,51111111 1 results11'111-1 in111 a-- dr'Op111111 in51.1. gr'Ound-level.. 1111:1'5—1-1-'1_. fr'Om- '.'1-1-. 1 7,000.. 111.11 feet'.-1..'11_.-'-' 1...at= the.:.'-1..-' tap'.'. ". 'Of5 the.11.. '11'1'11'1'1'upper scarp,11.11.11. 11It'O'1'-.‘11-1.6,500 .11at 1.111the f'O'Ot.1---.'-'. of1 111':the l'Ower.-'-"-"'~'- . 1 1 . 1 .l 1 .1 1 . fl _. :1 - _l _ 1' 1 _'..1 . 1 ..'. .. .. 1. 1 '. -1 . . .1- 1.. .-. _.1. _1 ,1 _.l' ,. r' ... '.T. 1- 1 ,. -d 1" 1 1" ' I". . The l'Ower flaw apparently'1. 1 {55111555555115.1555- lies:5 _- directly5 55 ' 'On_ :: Basementi}115"‘|'~.55151311_55[£|. System55511151511511; .35-15Ir-5_55-.5"'555'Ir-1_555-"'gneisses in1 the111—515.551.552.15.n'Orth. th'Ough_1_:1..1_11-_111 the11.111 presence11111-13111 'Of11. a thin111111 intervening111.111-111'111111 layer.11_.1i 'Of1'11 pyr'Oclastic1.13.1111...1~11:1. material,'1-1111I1111. at11. least11.1.11 locally,11.11111. is:1'. indicated1111111111111: by1311' the111:." 'Occasi'Onal1_11'1'1.1.1~'111.1'11-:_ blacks111111111: 'Of1'11 tuff[1_1111111111'1'11'11preserved nearF.1'.=.1' the'11111' Kipkarren11111111111111; waterfall,'-.1.1-.=1:11'.1... md1111111' theE1111' .'125115aggl'OmerMe-_1'.11.‘1'.L"_ '.'1'113 arutcr'Ops1'1-L111'I'1117I11. 'Of111 ' 1111..the'._. region...—1.1'.11.15.1111": 'Of1__1] Chemuswa'515_15'11_1.._ 5'111'111'1'11L1—..... (see11111.1.- .1 p.-'1“-. 24).1.111-'11 - East1_1111'1T and11.111__._' south--1I'15.‘.IL 311'.-. east-1'.'I.1.'. 'Of1'11 the”...-'11' Kingwal111151.11'1'.:11 swamp11'1'1111'1'1 the11’11" phan'Olite1"111111-1I11L1: everywhere1_"-.1':'-.'1'1:'.1'-1_. rests1131.11 directly1211.11:‘. an1.11"! the11.1. l'Ower11115111. v'Olcanic-1 11.1.“: :31. racks.'1_".1.-.'_1~ 'Of111'51 Tinderet.11-11LiL'I1:1_ This1_1'11 can1111.51 be1_'1. seen'1'.1.__. at1'1: many.1:.1.__'1 places5"...11-51'1 al'Ong111111113. the1.11. s'Outh-west‘111111'1-11-111. margin1.:_ ;.1_'. 'Of111 the1.:; l'Ower1.1.11” flaw,1- 11.. and1; .-.! is1. als'O-11~.1'.I well1111'. dem'Onstrated111-1-.-..--.~1.1111.11 in the upper-.II::- reaches11 111111111. 'Of.'1 the-11. Kiptergesfi"-55IFLUFL-II fifi-- river[1111":5 - where,'1-1111:}-_'_------traversing._1‘;1-.1_'.,11:|_I- 1 ——-5.. fi dawnstream,11.111113111134111”155-.I-I'I11":1' '11-I- 'One1‘1-.11..1 "J remains1"11-1L-1..L|.-‘!'~1-.--.- 'On1111 the".51."'I Tinderet- 11111111115—1-1111-1: v'OlcanicI'-'I-1'--:-'-11.11.-_-.:I-1 _1 1. 1 1- 1 a _J racks until the—.— 11' l'Ower5'-:.'1'=.'.1'1' ph'Onalite[11111111113111- 'Outcrops-.'.1'._1=11.'1'11'.'=1~' on11111 the1111' ridges1'.1'§1'1 'On1.'.I'=1 either:1"I.E."I.1"!' side111111' 'Of11111 the'..'111' valley.-..:1i!1"=-.'. N'Orth-east5"111.‘ ._'1—1::=..1~. 1'-:'OfLess'OsT|. 111.1111. the1.’ .1.=' 1'.-111112".earlier lava was" ' prevented25-111 T:.-' " from...".1 flawing1111- further s'Outh by hills11 .11'Of the.'1'11' l'Ower111111111 Tinderet[1':-1111:1111 valcanic1111111111111 racks,11.111111 thaugh1111111111; ,the1111. hills1-.:|.:1.1 did11111 n'Ot1'11I1 presist1.1111111 ta11. the11.1 west'1..- ._I' i ... . 1. ' |.- 1 1 .— .... E.— .. '..‘ .1. 1' '_ 'Of Lessos,1.-:_"11.':111I1'11. allowing'1-'1'.'1.5‘11 1.:: a11 tangue'11_1."_'_:!:_‘ 'Of1111 lava:11'1'1'1'1151'1'1'1'1"ta flaw in a11 mare' .' _ sautherly1'1-11 .13."- directianL11 1'. ' until.'l - again.'.5_'1 . blocked:‘-|-1'1.1_'_-1_-._"I_1 by1_'_"'-.. agglamerate_i'_"_--__ .‘_'| _'_'. ridges[—11.311111 s'Outh1111111155 'OfI1_5.||5 the5.51115 Kibebet1':-1151711311151 river,1:11.. 1 which'-‘I-i1'1._'. has1-1131.» etched1....-1-15'11' the1.111. junc-:1_1:-_ '1-'11 555555-5'155 1'1-1'. ' -_.-1|-. -5-. 1+ - -1. ti'On.151'.:'."j".. The_1_1-1115C 5 upper'1! 121.1:1517151-1111'111:1_1- plateau.-1 - phan'Olite-'1711-1111-1111.. r-1.115I -. east1:11.111' 'Of1'-1'5 Lessos_1_5| :1.".'1. ..I lake5'-1_-1.._.11 was".1 -.'.."1' similarly.'.11....:11-- ' banked1511:.-1'1'..| against11'__11'1..1111 the. 1 '_-11--11— '"5- 11.1.15; . 1- 'r -1'- 111-1| .._ 1-1-15 '1'-. .11 "11.1'1 . a" 1 1 l . 1 11' .- 'r1_'- ll- '- 5'1- 5'"? L‘i" lawer111.1 Tinderet11.11.1111 aggl'Omerates111111.111. ."II... which1111111.- can'1-1 be -1—1—11-seen at all. levelsL inI the-11'111'1valley 'Of1- the_.-I:_ Masaba11 east1..1:111 'Of1113' the111-11' l'Ower11111.11." ph'On'Olite111111'1111'autcrap. .:E . .1 -- |-:; -'I-.; 1 1-1'111‘11. 1.11 ‘11-. :5"-:- - 1'11. | I111 _.'.."- -'I;-|1--.' 1-1-. A.'1 small11155155111. expasure1.5511115515911151. 'Of1._5'1 tuff111:1' 'OccursI1'."-1.'..11.f1 between_'1111111—151 thel...— phan'Olite5555555"5555.5.'5— flaws.11-11.". f'Our111-111 miles11.11I11'1 west'1'-.151. 'Of Kapekabush11111171115111.1111111'11 triganametrical1111111111111111':.'_'E'1':1'1 beacan,1'11'1111111'1. and:1 rep'Orts were 'Obtained 'Of the 'Occurrence 'Of -1 4,, _ _ 1 _. .1— . ' . '. .. — 1- _ a1. narr'Ow11111111111 band1.1.111 1'1'Of similar11:1 1.1.1 material1:1..111'rI11' in111 naw-avergr'Own1111—111 "1. 11-11 gullies11'1'15—I'11'1 where11.1121: the.-.'-' S'Osiani'11."-'.11- river. =1 1 _ _ ., . '.'! 1 5' — 1 1'51— 1 - + + _1- 1 - - - 1":5 1—- -1--—1 I. runs55 1.1.5551- 'Off-1. 1- thetilt: upper5i_55555 5555 anta'1.555T55 "I1.ll the51111.1: l'Ower11.15: 55 11.55:. flaw.1.L555"15"1. This'. 5'.55'I c'Onfirms1._-55"..5..l.' 1.55" that1.1.11.1}. there1. _.1: wasIr5531.551} a1... sufficient_"1-11_ :151..-.. I1. time-_ - — r I. '1. 1 — lapse1'11 1'15'EI15' between53.571151135539151 the'_5'1'15 ph'On'Olite[_51'55'1'1'15_5".5|1_'J'1551|1_' flaws5551151151 '151 far11'"- the{5115' accumulati'On151CC115515:11|.1"115':_| 'Of1'15"! a11 thin5-5155" mantle51"."15. 1 :'5_‘ 'Of'5'; pyr'Oclastic:"|5_1'T'. '.‘1';.' 5." ' ' 5 5 ' 1' . . ---|. ‘_'-1._1- --. ' 1-'. "i: I.'I ' 5' ' 1 ".1. I55 .' "' -5-1. '5--I- ..-.I".1- -. 1111551559debris which'1'-'1'5'lIC_'5! weathers'1‘151'1111511551'1 111L511L55155'1151111!5'~5111'13|1mare rapidly than 1.the|'—1 lavas,---'-5"--1-'1 and1-151'1-1 has15111.11 resulted1-11'.L1.-1.1._"L1 in.51 the'.:!-'1. greater-.1"_1-1-1! recessi'On11111111111111: 'Of111 the111111 upper11111111 ph'Onalite1111111111.i511-' scarp.1'.-31111. !"-' 51 'I'I _I_.' 27‘.1! ——-L'-'I—.-FI.-I—-l- —- --1.-..-. {ii}(ii) Compo:5'ition[:':1-1.1111111511111111 -u——.-—— Specimen51:1:1:11111:r1 34/219311.211} 1.11.1111from the“1111: lower11:11.1'1'31 lava1111111 flaw,1111111. twa1.1.1.111 miles111i: [_.11'. north-west1111111111 1.1.1.1:1 of111' Lessos,1.1.1.1111:- has111-1' — - a11- fine-grainedi'111L1-L3111111'11111 porcellaneous111111.:1111111111 11111.11 blue-black111L1E-11'1 11.111 grooodmassg1'1111111'1111111111 1.111111with numerous111-11111111111111 small111111-111 phenocrysts,11111311112111.1111. - mainly11111111111 glassy1111111111. 1111111111111felspars 111111and 11:11:.less common12111111111111 1.1111111waxy nephelines.11121111211113; A.1. thin111111 1111.11:section'1111 1.111.111:shows that1.11.111 the1115 phenocrystsp11e1111cr1-5111 111-1.1are euhedral1:11'711':1-1r111 :11'11'1and part-resorrbedp11rL—IL111111'111L11 carlsbad-twinned1:111'111111111-1—1111i11111-111 sanidine,F.1-11111ii1111. less111-111.11 ..'-11:1:-com- mon1111'1111 11131111L1ir11s1-nephelines, 111:1:1111'1111111occasianal E111g11'11113-1111g11‘2‘5aegirine-augites with11.1111 11111111111'11LL1i11i11-11narrow aegirine 11111:.rims, 111111and 111-111iron ore.11111.. Iron11111: ore1.11111. ailsa111.1111 occurs112L11111 as11:1. aggregates111.1L111LL11L1'L'1 of111' closely-packedL11111L! 1.1-111111111111 granules11:11:11.11-1-1111111111LL11'111.1produced by the1111—. alteration:1'1111:r:1:'111.'1 of1'.-1'1111:1'1111111111111::111111111111131111.1'11La ferromagnesian mineral. The groundimass1.111111111111111111 1111i11L1—111-11'1L11:11'11'11:1111'11'111:~1L1'.1is fine-grained and composed 11111131531111:-of aegirine, kataphorite111111111111'. 1-1111and felspar,1'L11111-111'.-.'11111and prrobably11111111111111 nepheline..11L11'111L11'11L- A1'11 :1L1:.1111second specimen,1111112111111.11--111:'-1-:34/212 1'1'1'11'11.from the111.11 Onyoke111131111111: valley11-'1':11L1_1-' two1'.-1:11 miles11111L111 north-east111L11111—E1'1L'11 1:11.of Lelmokwo1.1211111111111111 market,111.111.21- isi:-'. more1111111.: typical:1111111::11 in'.'..1 111.11”its phena-p111::1:.1— 1:13.".11111.crysts, which11'11ic11 are1111' sparse11111111111 :11111and L'111'1:.'1:'.1consist of111:" nephelines1111;111:1[11111 '1'1-1111and felspar11111111111:showing111111.111: 11a hint11.111: .'.-1'of anorthoclase1111.11r1.1'.11L111:'.11-' twinning.11.1111111111ng. TheT1111 fifine-grainedrm—31111111111 groundmass1.1111111111111119. :-1L1_:1'111again consists12111111111111 of1111' brown11111111111 sodic1.31111: 111111.1111i111J1L-amphibole, 1111;111'i11::1.'1'e11..1:111.:11111aegirine, felspar and probably11111111111111; :1a zeolite11'11: mineral111111111111 1'.:1in the11111-1 11'.-'.:..1base. In1:1 111111.this 1::1-1L'case the111.1.-1'111'-.1.'.11'.:'111111:.111L1.1.11‘1.i.'-.amphiboIe af the matrix predominates111L11111.1i11111L1'-11:1'12'1111'111'111111111111.over the pyroxene. The'1'11-1: upper11111311 flow11111111 on1.1'-'.1 the1111.: scarp1111:1111: west1.111.111: 'Of:11 Ndubenet1111111113111: is11 11111121121111.111represented by1111' 51:11::11111:specimen 34/220,"11.2211 which111111.:1': is1111 a'.1 fine-grained[1i1L'—g.1':11111-'11 blue-black111111-1111. rock1111.11 carrying1::-11'1':.-'1:1';_,1 1.111111111111111euhedral nephelines111-11111111111111: 11:11.1and 1:!'clusters11:11:11. {_1(1 1:11.em. in 11i:1111:.111:"1'}diameter) 1111.21and 111.11fe1spar P111351-plates 1'!(1 CIT-1':cm.) ‘1‘-1111with '.1a hint111']? 1'11'Of flow1'1-'3'“? 1111ET'11'1'IE?"'1alignment. TheT1111: phenocrystsI.'11'11::1-'.1L'r_1.'.1.'1:1. 11111-1and dusters'1.:1'111-1‘1'1:1'1.1 'Of1.11. nepheline11L1'111L11I1. are11rL1 Iseen111-11:11 in11'. thinmm section11:11.1 111111 ta1.1': be111.1: partly11.11.1111. rounded,1111111111211. but11.11 with111111.11 occasional11121-111111 :11 crystal1:11.111111 1:1:113111.faces. TheT1111 clusters1:111-11L11'11 include'.1-11:11:11.1: iron1111.11 ore11.11;: and1.111.111 apatiteIii—3111111: grains.1.3111115. The111-L1. felspars1111:1111-11'1. consist1:1'=:'1.1.'1i:'-.:1 of111' 1.1'::'11111111—111'11111131'1carlsbad-twinnedcolumnsLL11111111111 with'11.'i:1"1 .'1-11111111.zones :11af inclusions11111111111111: 'Of1111' iron11'1'111 ore11.11: and111111 amphibole11111.11111111111.: towards11111111111 their11'1L111' ends.11.111.11.1- An.i‘111'1 isolatedi111|111L111 olivine1111111111.: crystal1:.111'111111 was1.1.'111'. 1:11".cut in11'- the111: thin1|:i11 section;1113;111:111: iti: is1.1. partly11.111111 replaced.’.:11:::.'1-'1'.1 by1.11.“ aL talc-like11111:—ii'111-1 material1111111111111 and11111-1 coated11111111211 with1.1.1111 small11:11:11 aegirine111-11.11.1111: crystals.1.111.111.1111. Augite.'1-11.11.1111: occurs11L'L'111'11 as111'. rare1'1-11".: euhedral1111113111111 crystals.1:1'11'::::1'.::. The'1'1'11: fine-grained1111c—gr::i111:1'_1 groundmass311'111111111'111'LLH consists1.1'-111111.11. of1:11' felspar1'11i11p11l' laths,111.111.11- cossyrite,1:11:1111'1'i111. aegirine,1:1-1:L.1_'ir1'11L1- kataphorite11:11111111111'i11: and11:11-11 11.1111111111110.nepheline. Specimen5113:1111111'. 34/3631—'1_.'11'1.'1 111.1111from 11'1“”.the .._-1.5...scarp .3131an the111.; Nabkoi-Eldoret"1..'-.1'11111111-1. 11.11.1111: roadr111111 is£1: markedlyn::11'}.L'113-.'1.-' vesicular,'1'1'."-.§'1-'2-i'::11'. the1111:: :::-11.1‘.1-.-1.cavities being3111-5-11; part-filled1:1111'1—11111:1.1 with'1'-.111”: 1111:1111‘11:zeolite and11111.1 1.111131112-calcite. 111(c) Lavas11.11111'1'1'1' 1.111of Tinderet1"11'111111'1'1'1'1 - - ..... -' ,_ ..', . :"11. - 1 :._: -. 1._-_I_ A.11 I'I'11111'1131'number 1'1;of .1'1_'-r1._1rare 1.1.111;lava types:_'-.11":11_"'11 1'1-._'..1.'1'occur 11111311....111'LL1intercalated .'1-1:.as -1:JI.I.‘.I[minor flows1.1.-111:1. within111-11.1] '11};the low.1111. 'I Tinderet'1'11111L11'L'1' agglomerate11.111111111113111: 1'11'11'11111111'1Lr1'11formation, and fieId.’1-1.11:1 relationships.1'1'.—':-1'11.11.1:1'1i111.1 1- 1.112.111.1111suggest that11111111111111"1'111':11p!111_1.1-'.:11:111some form plugs and intrusions:11.1..1'11.111111:1.' 111'of limited1111111L11 latera>!:':1-1.11'1'1i L1.1.":1:111.extent. Higher1-11:.-| '.L. in51'- 1.111.:the 111.111.111.111:volcanic pilel51111. 111'11’11.lavas 1:11111L'come 11'.to 11111111form :1a progressively111'1.'-:.11':.-:::111r:|11- larger'.::1'.1_.':.'1' proportion11:1'111111'11111'. of.11 the11:1: :.11.'1'.I'.1L-i1..:1::sequence 11111.1and in1.": the11:1: best.'1-1:111 L::1.'ITI:‘I:-.Lexposed111 regions1L11_::1.'.' .111. north-1111:"1'1: 1....111.east 111'of Lessos[_13111..1-: a'.1 1.L:L:-.:1.-':-11-.i11.:1succession 111'of 'lavasi.111::1. 1111.1'1L11L-r:1:111.1and alternate tuffs11.11111 '.:.1111can be:11: mapped1111111111311 with1111i1.1 some1111.111.L precision.[:11L'L'i1i1111- '1.—1'11:-The 1.1'.1::'L11'1L'.':1absence 11.1'of '.1a :111'1'11'1111'similar 1.11.1111L'1'1LTL'sequence 11.11on the1.1113: map1112.111 further1'1-111111.111 51111::1south may111.113: be1‘1-.1 attnbuted1:.11'1'1...-11 in111 part11.11111': to111. the1111-1 nature111111111: of1.11 the1.1111: soil”1111.111 111111and vegetation1113:11111111'1 cover,._'-111111.11:- which11'11."1.i1'.:1'. make1111-11-11: that1111.'. part1.11:1: .'1|of the1 1 11area'.'.11 less11:11.1: 11111131111111:amenable to:1': 1:11.111:detailed11:11.1.11LI11131111.1111-1111111mapping, though it11'.:1is true11111: 111.1111also that11:11. massive1'.-1111115111: agglomerate'11.'_'1_-11311.1-'..11'111-.1.' remains1'1:1:'.:111':11 the11'1L111:'1.'.'1:!L1:11i111.1'-1':predominant member:111'.'111-i11_1.1'111to aL much111111.11 11ig1'1L-1higher level1131.11.11 in11: the11'.-'.1 forest11:11:11 area:1'1'-'L"1'-. to:1'.- the1111.1 south.1:111:11- It1: appears11111111111111 probable1111-1111113: 1111.1.that while11'1'11!1: .1.:a major111-11111 vent,11:111. 111'or 111.1110:series 111'of vents,'1'L'11111.L'.'-I":1='.1'1'.:1'3.1.1|continued 131emitting1111151": 1 pyroclastic311,-1-111;|1L-._1-1. 1'.material11.1131: 111 1.113111111141111sporadically1.511111'1111if111111-11.11'113throughout the 111-'.1life 111-".111:of the T11:Tinderet1.11.1-1:1 volcano,1.'.L'11.1'.1-'.1. :1'..-subsidiary[_'l :'.1:'i. '.11'1' vents'-'.L111.1.1. 1.1.'1-11'1:were 119:1}1111'111i11113responsible for'1" 1.11.;the 1113111111extrusion11:1 111'of localizedi11L11=.|:'-1'.L-'.1 lava-flows,11-1'1-'1':-f'.1'.11.1.'1:1. 111111and 11111111small series.'-.:1':1":~1 111'of flowst'.-:_11.1...1. '.1-1:as 111.".L'L111occur near111-”'11:" Burnt“El-1311;111:1151.Forest. In11'. 111-.'.-'1'1i_1.1i11.'1.-.1the highest 11:11'11111:.-.1.'1:'L".1111.'part of the area the :1":'.-1-:..1'1'.1'.'.'.'massive :11:_1L{11'-.1'.L1':111:.agglomerates '.1-1'1:are 1'1-111111111capped 1.111'by 11a 1111111113.—number 11:"of 1.-'.'.r:111:-1Lvariable 1111-111:.-111‘.=-:phonolite 1.111111.lavas 111.111.with .11-a 11111111high L11'L1111:1:“t11111proportion 1111'of 11.11interbedded.1...-'11'.1-.L- 1111.1111—111-111light-coloured1.11'.'.'"1 tuffs1'1-111:. L1-and1.: ...... '. 1...... -.. .' ...... :.. 1. .1.. .. '... . .-.'-.. 1. .- {1'1-1141:11-ashes. Again.-""1..r—:.1.1I1 1|.11.-the 111-1131111111.:1standard 1'11of 1.."1FL111L11L-exposure 1":1is 1.11.1111»below 111-.11..that 1131-11.:ILL'1required 111.1'to makeI'E-IQLKE'. the'--1111." 1.11.."1.1L.._J_[1[11delineation -' .1.. -' .' ..1111. .. . :11. 1".of 11.1111111111.-:individual 111111.11flows -.'11-:-~~.1:11.'possible. '1- 1. “ -1'1. 1'.. ‘ 111. -1 1"..1-1. -1 1- -' .- :.- 11" P'II'I'I. I -i-'-1. . . "-:| __ /"1 The1':11-' 11'.-L11agglomerates[':'-1:1— .'.-1 ':1 L11.of the:1‘-L 11:L-1:1area 1:101?tabout LessosLLHELN: 1111!:fand '.|"Ito the11.6 ‘1’113'111west 1.1.'-111:1and 511“}.[11'1'121113south have several11:11:11 intercalated:':11-1'L1'1111'11'11-11-1" 1.1-111111111111basic lava- flows1.1.1.111.“'.1-11- " 'which11.111111:" 1-1-' prove1111131111:1H : to11'-I'- be'.11.'- J-Iu'melanephelinites.111:.111'.LI:11-L'1111i11::1111.1:11r 1. '-1 ‘I . and‘c 11111'.melilite-" :— 1.1 bearing"111.1111; .1'111:rocks..111?- 11:In 1:11:the 1.1.-.'1:area ':1'-1.1111about BurntEli-I111: Forest1"'1'.1111:-11 this11 '1. 111::1iDIL11111.agglomerate is1.1.' "1'-1-:'r1L:I1.overlain by1:11.1' :':a 1:111:1111-11i1-L':distinctive I111:.111.L11'11.'.:phonolitic 1:1:11'1111I1115-1L1-nephelinite, 11.111111111111111phonolitic 11112111111:melanephelinite111L1 1111.1 1111111and 1111111111.melaphonolite...111111111.. '11::Tht: uppermost1.1::-I:1Lr1.1:11-1'iu L. .--1. -1.- - ..111-11111-.111—11111111111111.11:11111.1:1:.1111.-.-..31111111111111.-'flows- - of- TinderetH 1 .-are ..more.- normal. - .._-_" phonolites..._.1 . 1‘. .. . 28 (i)51311111111.“Phonolitic. .' '.' 111-11111:-nephelinifes..1155-5 1111:The main'111111 ji‘Ii'1L1I:-.IEII.iL'phonolitic II.5:'.nephelinite:1i:I'1iI..1iLL' 1111:5115occurs :15as 11.5".L'I.5111111i.111a substantial 1‘1-.2511‘5'flow 1311911131111extensively 9511-1115::exposed between55.5...II. Lessos3-1155515 .1111:and Kipkabus.15.1 1111;111:155. ExceptL'1LL'L:}1L in the111: 111:1'I'1:.'115.'extreme 1:151:51.east, where5511:1'1: it'.l liesiIL 5 directly51.151511} L111on 111':the upper51111115: plateau1111115111: phonolite,51151 115-. it:L L'1I.11.5caps flat-toppedi‘;.—LI11.5.j ridges,i'iLig111'L 515-5'i'|'_-.-'[1I.goverlying softer5511:1511 11gg1311'151'13LtEagglomerate 11.155and often.11:i1 forming11:-i'ii::I..:I a:1 small.5i111111 scarp5551111 feature.1511-11115. _ In1:1 5hand-specimen11..I.i...-5.I'15'-.:1:1..-11. _ . the_..Ii:. rocki111_ __1_5. 1.15..-(34/240)I5 5 -I1_4551'.-'-.II isI.-..5 variable5.11.511:. 1,1 -both11.1.11._ ;' in'11'. .5151:size 11.151and. _.I 51.1.5.5density.1.-. -. 511of" pheno-111mm—. crysts..-i-5_5I5_._ Typically,!'5-'I1'L:'.I.!!_I.. 1.1511151large euhedral51111151111111 nephelines11L'11i1L' .i1L'.5 carrying511115-111; cores'.'-.11515 of511 inclusions11L'ILI51111'15 11L'-..'L11occur singly5.111115 ..'-I.'or in'11. L'iI.L51I."1'5clusters .5I5:ILIII'Iaveraging 35:. 1.2 cm. 5551111111511diameter while55'11i151 ELL11111L1111iTabundant prisms'1'.'i51115 of111‘ .'1.a black111115115; fero-15'1'11— magnesianHILL-511111511511 minera'l11'.1115-1111 (0.515'}- 'I'.-l 5::.'i1._1cm.) and euhedralI:LIi'.L'1'JL'..1i amber-coloured11111i.IL-i'-LLIi.i1L11L'L‘] sphenes51111551515 (0.5111.5 cm.)5111.1 1115-are conspicuousL"..".-'.11ELLI:1'.;5 in11'. the1111: I.I-.'L'ciigreen-black11111-511. groundmass.11.101111111111155. Large5.11135: felspar1111511111 phenocrysts[11151515151515 (1.5[1.1.1 cm.)L'111. 1 1111.151:occur occasionally-1-.'-"'I5:.'.111:i‘.1j5-LL1- and'.'.1'151 smaller5i11'.I.I|.5'.=.' felspar1'511511111'51'5'511115crystals are1115-1 locally1511.1-115-511i1111151i1.common. On{3'11 55511111'II'weathering the1111: nephelines111111E1L'iii1L'5 111:.are rapidly1151.1ii:iiI.- destroyed,1125111153111. leaving1115'ii"1..II the[[111 rock11:11:11” 511111551115surfaces liberallyiii11:i'11|[5' pock-marked11113154111111.1151 and11111'1. . I ' “L . r . with551111 .'I.i1an occasional.1:-35555111111 upstanding1111515111Liii1'g. 3:11.555:glassy felspar.151511511. InTF5,I.. thin1i..11-|: --section55.511511.1-1 - 1. the'I.115.- .- large1.11I:I.L- 5. euhedra:lI:'L1-5_'51151]' 'Iuii Iand.11...I1" 5111111551111subhedral nephelines115111 1111111115 '.LI'L'are .5'L'5'11seen to151 have111-1111: alteredL1115'1'L'Li 11iL111galong cracks11:11:15.5. with551111. the1115' formation‘55'Iri11LIL'ii111'1 of111. cancrinite..'.-.11.:L'i11'iiL'. TheyFr]'-:_-_ include:.'.111L11'..5-1 115152113.occasional(1111'. magnetites1:11I1"I55 and111151 pyroxenes,11515155111515. are.11-..1 sometimes5.111.311.1125 inter-I.'.'=.I.-::'— ' .-l-. 5.grown5'1'5'.-.'~.1i 551111with the15' pyroxenes,11511115511125, 111151and 511111511ii11115sometimes include1i15'1ILLiL' 1111111115groups 511"of 51111517.small pyroxenep'.-'1:i.1:~.'.L'111. ..'1'I:':5".'.i.5crystals at:11 11115-131their middles.I11ii'.iL'.'i'i1I:[L51 The ferromagnesianiEI'I'LH'HflgH1351-15511". mineral11'1i11111'11i is15 g1'green:11 aegirine-augite,L'"LC[£ii"[I'113-Lil-nii.fl. and111151 the1.1:1111111111—pheno- crysts:i'5'515 occasionally1'1L'L'515I'5111111iI:111151:have cores51115.5 111of augiteEiLigitc pyroxene5151511151 1151. 3.11151and are:51': overgrownL5II.-'-..1:'g.1'5155'11 by115' narrow11111-15155 bright:11-g1'1-'11 green1.I."LIL'i'I. fringes1111115315 L1.Iof LIL-IgiI'iIILLaegirine. T1111The phenocrysts11515110515515 are:11”..- 51115.1often finely1ii15' zoned,1.1115111. 1i'i1:the 51111155zones usuaHy51.51.11“iI_I.1l.. 1.15151;being :11-115:1:conspicuous5 111.1115 }_15.'15I.-'..-'.5::'.between 51111551111crossed nicols1111:1115 11.5as series5L'1'EI:.5 1.11'.‘of L'!1115'i'1_1115chevrons 1:1'5'155i11IIcrossing 1111:the 55151511115crystals 1511'for the1111:. gi'L'5L11:i'greater 111511part of111 their.iiL'i: length.15115-2111. The11111 pyroxenes115-'.I".'I.I'.1'1115I.I'1 occur11L'L'Ili sometimes551111 L'1i11151..'5 as[-5.5 51111515115...clusters, associated"[1:12Li with551511 1111115.sphene,11:1 magnetite1.iILL.-’_I:iL".i 1_' LLIILI.and 5:111:11]small prismatic11111511151115: 5111.1.111115.inapatites. In hand-specimen111111L.—5I1-:.'L'1111L'i1 the1115: rock 34/2301 from1. :1111 two15511 miles.'11i§1.':5 5-:IIII.11-5'.11551south-east of511' Lessos15155515 isi5 richer1'1-.1151 in:11 felspar1511511113 phenocrysts,[11151155115555 and151151 with551111 5:11L-Lii111'smaller nepheJines.1ILIL1}15I.!i:'15'5. Th:The £3:"'ILl[1ICi?‘I".IEL:‘-.Sgroundmass retainsi'51'551i115 111:the 5111:5'11—1111511115green-black appearance,51111511111113: 111115and proxene1111151111: prisms1.1111111115111111and LIi11i15'1'5L'1.1i51LI.I'-:1_iamber-caroured 111111131155sphenes 1.1.111can both[1.51111 be1'1-..' Lii55i1iLIILi5f'i5:Li.'l'i1.L'distinguished. The 5511515cores .11'of 51.11111:some of5'11: Li's:the larger11111111: .1111zoned15' 'LLaegirene-augite'I._-'ii.:i11:— 11:11.1115' L'I'crystals'-.51.'.1‘.'.5 L111:are neutral11511: 111-11 1.11or pale1.11111: £151..green111 ['11in colour.L.LIiL.1L1." The 511115111155carlsbad I55I11:11i111.1twinning 11155115355151displayed 1151111:by the f5.-'.[felspars.111. .5 i5is 5'i.IIiJ.1!Lvisible 11511.1ii1.both in i1:Li1Li--5i1:L'ii11:11hand-specimen 11115.1'and in111 '.i1L'the 135151..slide, where5511511: 1111:the 1.:i5;.'.-'.'::'felspar -:'i'j-.'5111i5crystals f5'11'1'II.form 5111:.[1small 51551511315clusters, 111151and 1Li'1.'are partly:1LLI'1iI.‘ resorbed.11115511111115. In1:1 bothi1111i1 I:;.1L'L':-specimensI'.151.i15 justjL.-5I. describedd115'..'_rii'.1515:i distinct5111:1115: flow1":1155' 3.!1'51521111'5115structure is apparent1.1111:.1511; among1111151111.: the111: felspar15":511111' [111115laths '.'.fof 1115'the gi'Lt-i11HiLii1'iLL55.groundmass. T11:The pyroxene1151.1: :-111: of511' theIi11: "11.11111groundmass51.111155 551155consists.5 '5'1'of 11111151.-small aegirine-augites1LLILIE:'I':i5_I—LILI.II_I:'1.:.I'. -.'.15'5'-.'I'LI.I"1I-.I:1overgrown with5511.11 '.1-5'1111'111L'.aegirine, and..I'ILi i1'I.is .1..-5'1111111:L'Liaccompanied by5135' ii111:—I:I.I.'.11.-15:L'i.fine-grained mossy11111515.} "'I:L".I'15flecks 11fof i--I.L..-.'late stage,51:11.15: interstitial,II'. iLIIIt'I. [11115511brown sodic.5511: '1I'L1L'Ii1'1151.amphibole. 'i'l's:The JLI55'low refracting,151111511111. weakly5511111511” birefringent-:|1'.'11L,I5:11I: 11111111111351matrix is probably11151511115115 mainly111:1?11‘-;-.-' 111':ph.11ii1i:.nepheline. :'ii(ii)'1 PhonoliticF111111111‘I'11' ' IIILI.'[11.I11I.11.I[11.'.-"11.51155melanephelinites 11115-515111;Traversing up111.1 the111': "111511.lava pileDH: the1115'. 111.11i1511111':phonolitic nephelinites1:1:_.'.Ii15:|i1111'5'5 become1111:111i15 less|:.'.5.5 porphyritic.1111111'I15-'1:1i.:. Apart'.11111'1' fromiii-I.I[iTi theH15: lack'1':_L'k of111“ largei111IIIL' leucocratic|L'L:L'Li:.'1'ELLiL' phenocrysts1111111111515'515 the111-: 1115-1115lavas are,11151. however,11515525151. 551:1.strictly'11'. -'.'I.ii1i11::L1".Li1iL'.comparable 55'iti1with 11111.55:those ‘.5'155511'111511511.lower down, butiILIf itii is1.5 impossiblei11'1111'I55'ii1i1: to1.1 .--'.'.1;.-'say whether55'i15'11'i1511' 1'11:the 1111311151:higher 11.111111151115115exposures represent1511112515311 the111': 11:11.11upper part11511 i 511of 11a :5i11I._I:5single111.1155flow 1I1'or LII.a 5511111111:separate 511115:subsequent11:..1i11 ”ii-1155'flow 111115-from the1111: 5.11111:same 511L1i'L'51.source. Specimens'"11:_I.11III1.5-1-5L11Li34/281 and 3.5?-34/2452-1.‘ from"a 1'111I.'i west5'5 :51 of111‘ Burnt11:11:11 Forest[11:51:51 have115151: fine-grained1'i115 —I'Ii.-..i.... green-1.515'1L'i1 5:1:5'grey 1115555bases 51111151113carrying 55a 11.155few small51111111 nephelines,115111111511ii'1515. -.-La few1555' LLI1IL1L'i'-1:LI'LLILIL'=:LIamber-coloured 55111-15155sphenes 1511:and numerous115111'IEL'IJL1'5 ferromagnesian13.1.11'1111111gi1L'5iLLi1 prisms.pi'i5i115. .111In a11 thin 111iL'L'slice 511'of 24/28135255} the1115' nephelines11:11..1:'.ii115.'5 11.are foundILIL '15.. to151 occur5'.-.1::'..'i: inii1 5551i]well 111111111326.rounded ..'lLI.511:1'5.clusters, 1115totally5111': includingilTL‘ilJLi[‘:'|g 5111.11}.small sphenes5L1}15'11515 11:1L'iand 115-1511111111:pyroxene crystals,cry-”5111115. while'55'i1fl: ”Elli:24/245 1}1L"5'they 11115.1also occur115153511 LL15as sharply5'5Li51'11i5' idiomorphiciLiiL1I11L11'11i1'5: 5:15'5111i5crystals and as11.5 L'iLI5'.li:-.'5.:clusters of511' idiomorphs.E1111111111I'ph5. T‘rI.L'The pyroxene115111551'5 515-55115.crystals, 55111111151155sometimes in:1. 1511i151111gradiating clusters,L11151511'5. 111':are 5111:1151zoned 111.515.1511.:aegirine- augite,:LLLgit". with55ELi'1 1:511:11.cores lighterlightfir inEi1 colour5'11i1I11i' 111151and with551111 wider5511.11.11 1:5111'IL'1:'11I1extinction angles.:111gics. InI 34/281135-11]"I . idio-iLi;11— morphic1111.1: 111151: and rounded101111d microphenocrysts1111..'.1'111111-2111111i'5'515 of111' iron111111 1115'.ore 111':are common.5511111111111. The groundmassesI.I1'11111155111111.5555 consist5111151151 of111' 15.155151felspar laths,l'.1-’.i'1.5'_. aegirine-augite,51111.1i1'i11LI—51113i151. magnetiteI1111giicii11: and11115i nepheline.111:1..1: 1111.: [i111.-’5-’1I.I1F15'.I'.I'5'1I'.I‘L'.5'(iii) Nephelinites and5'1115'.‘1 1111-.-"r:1111'_i1F::.’1'11.I'.'11I.5'melanephelinites 35-1111'11:Mafic LLi1Li-215ELLLIIL111151undersaturated 1.111115rocks 1iL'1.'LI.i'occur 1511at 11.a 111i:1'.1:.5I.I'number :1of 11.111111111111125exposures 51:115111gamong 1115'the ”Find-"1511Tinderet -.5;_I.I'..'1i11.:1L115'5.1115151agglomerates. They 1151111115usually 1111115111appear .'.-.5as 1115:.5—111155'5lava-flows 111'of limited 55151.1.extent, L15as in 1115':the Mtetei1511111511 valley113l5-15ILLI'1dand west55.3.51. 11fof Lessos,151115115. but '.'11511also occurLIL5:511 115as 5.1'i:L|ismall irregular 11111515111115.intrusions, 51.11as L11at 15351111111Nabkoi road-junction.1'1I1-LL--i iLLi1L'1iLII1. ..... 29ILII'J A nephelinite,1'1CI:1?'11:11.1.1.'11:. 34/329,.111 33'1". collected1'1‘1111'11cd from1:11.111 a12. minor11111111 flow13111111; '-.1':-to the1111' north:11'11".11 1'.-1of the1111' Mtetei.'1-Items: I . . . _I I 'I . .".I‘I .'. valley1.1111111: 1111111.road, is1.1-'1 in:11 hand-specimen1111111111111 11:11111211 11a 5.11'1211111—1._11'1.11-'green-grey 11:11:11rock with1-1. '11 waxy11'51111‘1’ 111.."hexagonal113111-111 11131111111111nepheline I ' phenocrysts.11111'1-1'11'1"111 up1.111 11.1to 4 mm.1111.1. in111 length.1111111111.. 111In 1111.11thin 111.11.11.111section the111.11 largerI11. 13:." nephelines11:17-11.;'.-l'1.'.-.11 .'.'-'.:'-.1are seen1112'1 '..'.1to I1--be 1 '. r- r1]1--.-.-:I 1‘7" 1: |w.-!.-L-.- . - I-.---u--:-- I- 1 - - l r— - -'— — ---.---. ,.- . r--—..-'I1'. .13: '111- 1.1.3-- If“.I _..1 1119.111 11.11..1.'.1 --. -..-...-_1.1..1...--1.~ 1... .1 I!_-- altered1111:1111. along11'-11.1172:.. 1i...'11.-'.'1.I.1..1'11:['.-.l'anastomosing - cracks1.'.1-511.111.. and to lie in a highly._ . altered groundmass-. carrying_ .-.h "'. I'I' remnants1'11'1‘1‘.E'Ii:1:1111-a.-u. -u of11.-I'-1. poikilitic-1571111111111.-..| - ' ---. 1..crystals-.1---. 1.1.1:.11-'. 1.11of- 'II faintly1.1.71.1;11' 11 1' 1" ‘1‘1.I..I...-..II.1.I!1.pleochroicII '1 '1"-1'! -'I.' I 'I- .-'11.__-.:.'aegirine-aguite.‘1.. r-1-1I.I..--..._1!_..'..-II:. I__ ‘- 'I‘: SmallIII - ': .-I fresh..' 1. -.and "III I' - .- I . I._: -.'. .. 1’" l.-.:_: |'|'-"1 |l"'I""_-"|..I-1: l'. 1.-1 .'-. -'I pseudomorphosedp1.LI’..'.1.11‘1‘1-.'.1H11.1..-31111111111-- .' nepheline11513111111111;- 1. - I ... crystals1.11.11.13.11. are-111... abundant.1..-..1[11.1-11:I_. in.1.- theI..- I.-...1-.1.....-..11.-.-_.groundmass, which1--1.~_.. now. 11» consists.'111111'11111 of1.15 111111111some 5051.] per111111 1.111111cent calcite1111111111: and11111} 111.111.1151zeolites in111 .'1'1111'1‘1crude spherules.11:111-311.: 11.11.. "I. :5 --'1-'-'-". :. --.;--. II ‘1. ' 1 ".'1 '- -I'.-I-.-1. 1‘1.-1. .' -I.1 -. 1.1-I -I-- -1 “'1.1." - -- I'—-.I -_ 1 - .: -_- - "1."' -1 A_ _'I...5,'-.I'.IJ‘.._.second typeV'E-I... (34/334)," . .I 1. froml..|.I':.I| beyondL'-_ --.'..'-.... the..'IL 'I-1...'11_.end of'-.'|. the1.111.. motorable:-II .\_J.|.-.!. ._ track,'_..-1.1.l'|.. 1..containsJ-I_.-" ' _II -.- .-. -]:--: -.-_-_1 .1- T—I” 111 -.-.:---. I-~|.'.-- - u-"'_"'r-I.'1d .' II II:'1:I;- '1.-1". '1" . III lIl'i'-'|' 'hl'-"'.T|-". '..'1PJI-I l‘h—: E“.'". 3 mm.-diameter'!:--'..'L'1:'_'.-.. nepheline..L]'1_.l.l1. phenocrystsIII'..1.-.l-.'L._. ' .‘1 “'1 -.-.'..and a..'l high.I—l.:.:| densitykl'bIl-h'-I of'-"- ferromagnesian11. |'-'I'.|-'.i:1.-..-‘=i':_-. prisms.I1 .I‘. . - . '- - - - ' I - ' . ' - +I1r‘-.' .' .;' ' 'I.'- '1.-.4“ 'L III'I-III1PI -1-1 "" .'J '-'1'r- ':1"‘ '1_'_"_- "7| .I '. 'I1 "r'. "_ '1-'r"|'"—'..'1- t""‘ '1' '._ It1. is'..'.- classified1.1.3" '..:LJ Ll‘Ias 1.'.a melanephelinite.I.'I.|'-.-I...'1_|-_III1- Phenocrysts1111:. I'I1I_I'Ijr"1|..“1.« 113of .‘..L_'_'_..11:1'-..aegirine-aguiteLia—FLIJLE- withr'r.L11 LL'__-_'_._..l.:l-_aegirine fringes1.1I1'.'I__.1._- are11.1.? common‘TII'I'IUII and.1l".'11 11:1.the phenocrysts:WhLl:L--.I_.I:1'1.'I1 of1.]. nepheline1‘11;I‘.|J‘|.L.11.IL .II-1.are mainly['1=.-.1'1"!1}1' 1.euhedral,.1111...'1..|_.. but1-:_.'T_ some:11..--.1EL.. are.1111. resorbed and irregular, while some are highly altered. The groundmass consists of aegirine-aguite, nepheline and iron ore in an isotropic felspathoidal base. .. .1: _.-.-.. '1 - 1'111 1'.-. .. - .:1.. ...1'. .. _.... .1" ' _. '. . .. '. .. _ .. ..1 Specimen52:31:»...1J; ‘1 34/222,.‘1: .___ I fromllIL-'III.II oneL..1:.._ mile!I|__'1L south-west'1.-._.'._I:.-'-'.'1._.'11I of'..-I Lessos,I1..._'-:.'-.'._.-':._ is-."1 a1. paleJ'u.'__ grey._"..=._'1 rock11141.1". with1‘.-I1. I--- ..1... 1 .. .. .1 .. . .. 11 '. -.|.--- ..1-'1.1 . - —.-.11 . .'.. 1 . abundant.'.:II'I._'I'.L1CLIII:L pyroxeneP1-IL.I111.'I‘I.. .'.IIL1and olivine..‘.I.'l‘1-'I|.l1.‘ phenocrysts[711.1111151'1'1'. '1.1 J-Ll‘ziiIIand is11.1 classified1.1.1.1111!'.|.1.1 .11as .-'.|-..an 11.1111.olivine nephelinite.I:1...:!':."1_]1I.1.. III 1-1. . I - '1-1'1'11+'-""1'1 ' _.. :.- ..1-1 . “'..'-.'._ I“I -.~I..-. 1'=.'- — .—|.- l-. .'.1. .I 1.11.. The1.1-1.. pyroxene31-11%" .II'11.1I.I-IL.' 11- is1"- augite,.".._'.:.1.'-.. weakly'r'r'._1_i."I. pleochroic1,111.:11-1'It.1II'.I from2.11”.- aLl pinkish..-'1'.JJ."-..‘.. tingeLI_.;__‘-..- to .‘.I:greenish,'1.-...... ‘.-|.. in1.1 euhedral'LL.JI1.'-.-L..-.1. .'1 ”..1. -.-.--.----].11-1.-3 .111--~.-]- ..11 --. _ __ I. _:_ -. _11| ' _ .. . . or slightlyhI-r-‘II. resorbed1L-II"-I'- '-.-L-U crystals1._'_'-I‘:-1.1.l:.". up1.1:! to111-I 3_' mm...!.111. acrossL'Iu ..'-1...: which'IILI 11.11. areI. '1‘ sometimesII '..'- I'V—II‘ zoned"_'.' I_I. and\lll f . __ '1'1--. .'.' .. . 1...... -. .._- .. ... -_ 1.. : . .1 .' 1'- occasionally1.1.111. 11.-1.11:1 twinned.I...'1._'.1. The1 1|... olivines1T1. ".|i{1...'1. are.'_:'... less.1..;~_1_'-. common,'....._.'.-I:'!i'.'-j. and._._ .._. are._:_.1..1 roundedi1 1-:11]-I.1 ..:_._'.and fringed1111—11.... by'..._1.1.1.11111..11coronas. . -. .1... . of11...1" expelled1111....-11..I. .II', iron-ore'._1.-..-r1-1_11.1.- granules..._..1111... Alteration...---1I...1...1.11.:.'111 -..-.--'.-r1 hasI—.-.....1... occurred1.11.1...11..- .. :I._-_..IJ along.:.-11-.1I-.j cracks11.11.1111.. ._ |... to__1..- -u iddingsite,1.111111511111. and11111.] in1.. the1111. cores1.1-11.1 of1.'. theI111 crystals1.11.1.111-11 to111 serpentine.11.}.1.1T..11-. minerals.11111.11.1.-.-.1. LargeL.1.'.-_.__1 grains13.111131 of '.- .—. -L .2.. ... '.- -...1 1 1 1.1...1 . ...= . ...- .. ..1 ': iron'-"| ore111'1‘ showing111'--"~'--"--.11'. euhedral,111.!-.....'.-.'.'.. subhedral..11.11"111'11: or highly1.11.111. embayed11.111.11.111 shapes11 are.11. common,.11. while'.-..'1- I 0': 1.— .I |——1—. I - 1. I] p. ..1”. -- -|‘ r' —. I I the'1-.. groundmass—-. _1_ 1!... J LI‘I'N isII' composed|.. ' 1"1' 1... of abundant4. |..-] nepheline,'|_ LI smaH" 1.1. J augite1.1-'..: '1. prisms.l 1":. and|_ |..; specks" 1.1.1“ "I 1.'. of1! iron' 1'1—'.' ore.1' 1.. IIIITICThe 111111-111small 1"'~'.I1.11..':-11'111'1-1.exposure 1.'.1IIof bilSic121-11131: lava111'-.:1. :1:at Nabkoi51111111111 1.1—'.'(34/256) displays large augites up to 1.51 '1 X 0.81.1.11- em.1...-'1. and.111 olivines.111 11.1 (0.61111 em.).'-11' and1'11 proves1" .111.to be11: an1. analcime-olivine.111 111'-1 111' nephelinite.1' 11.11-11.111 .- .-. +I. I. '. _-J. IL. HI : . . _ an; _I -:.. J. I .-' ._ .. .-. - u-.-- . .. _ -.. :1- _ .- - -: In1.1 thin1. slice11.1.. the1.111; augites..IL1_.-_.'I-'..'1 show11.1.1.--.'-- pale11-111; greenish-buff__.-_'.’l.1.I_-1-..-..'-..:_'1I cores1.1.1-1-.1. with1'-..... 1'1-.1..-outer mauve-...1.-...-1_ titaniferous.:1—11.111110.“- zones-'1 111111.11_.'dusty 1111111with 111111-1111:iron-ore granules'.i'|_l'll1'I"-1.II.I;. __._1._. and';I_I.l_J'1 11‘-7‘the.III‘L.I. I“I|;II._II.|.L.smallerI-'-'- -I|I'I'.- JroundedII '._I'c'l._ll'"IIEI-H'i‘_1_... 'LI-l!olivines"‘1'-1.r.l.1.."‘-["1 I" ”41'La.|11_are1' 1.'.again'-|:'=i_‘_]:1.:1 . pualpart-'.i'I‘ altered.1:111'111'l ”111to 11111111115113.iddingsite 111111a;nd 1.1-1:11:11‘1111:serpentine. IrregularI1'1"cg111.1r 11111111111:1'1__1':1'-..1:phenocrysts 1:1."of iron11'11-1'. 111'-.1ore 11:':are 1111215111111}.possibly ilmenite.'Ir111:1'1111:. 511111.111Small 11h:111:1.11'_1.-'1.111phenocrysts 111111and 1"1_1'-."~'.-1'.'1.11_'.T:=_'111-.'..1'aggregates 1.11of 1'.r_=1_.1._1_:_1_-1.1Jragged plates3111111111: 111of phlogopite,111'.-:11;"-'-."1_-'.'11I'.1'1. pleochroic51111115111111." from11'-.1111 111111:pate 11111-1111.-.I'."-1'1"'-.'1:'1yellow-brown ‘.11to 11115111.:bright ."1:'11-.I'.11'1"-.1'11.red-brown, 111':are 1.11.1.1a'lso present.191111.111. The[1". 5151.111111111111groundmass 1.11111111111contains abundant11111111111111 11:11:11rods 111111and prisms[11111111 1.11of pyroxene[111.111.11.111: 11.-:11."and 1.1111111small 1.1.euhedral1111:..1'1111 grains'._11'13111 of 1"1'111iron ore111.111".in .'1a weakly-.'..'11'.11'I1' 1111.111birefringent1.1;.11'1' 1.: 1.'..-111:1-base 1111-111111z1121-11composed 111'of 111.11nepheline.111111. 1111: 1111111and 111111;:11111.analcime. A.-‘11 .1'.1_.11.1111111.1nephelinitic lava1.11.1 .:111__1.11._.1carrying 1'1..l.11..11mellanite I._1.11'1111.garnet 1.1.1...-1...occurs 11.9..high within11111.11. the...- Tinderet.'1..1.1.1.. agglomerate.1:.:..-..1-.111:I11.1.. on1.'.1 the[.11. HighlandHII1_111|.1I11.1 SawmiIIs'.'1-L11...... ':1 road1’1. .111. 1-4(34/359).1.'-..1 Pitch-black}’_I....-.L1_.1.,1. bdrm...garnet “1111.11.11.crystals 1of almost1'111'1II'741: :HIq-IUHIHIcircular I"1"1_I'1I.I.II'.1'1..I-'TI1section can3.111.111. be1.51: recognized.'I':|:'1Il_£1IIIII-::C|11 in”Ii hand-specimen,:I-IILII-ILIIIE—iI‘I-TIIf'L:"1I_I5.I!_IIII|L_.'.'II|. lying1.'-II:'_ in'11 .II'.a '_T'II-L':green-grey groundmass1'.—.1'1'111-LIMTJT11‘3 crammedL..-.1J.IIl|-_-ri1.-1.II with-I'\H.I1III L'.]1.L—1..1[..Lleuhedra'l nephe'lines..11-III1'11'C'...'I11_“1. The]I.L latter1.11.1...... I'IL-are large.1l-.1I-_.'-— 1...1'1.1and usual'ly'.4‘1-=.I;ill'_- 11..".'__L..clear, 11111but 11.11111sometime.'.:1r1*1. 11113111111111include 11-11g11'11'11-1111g1111aegirine-augite 1711111111.crystals 111111and 1:11:11.small 1111:111-1'11.sphenes. 1111:The 1111111111bright 211111111green .'1-.'1‘111'11‘11'3-aegirine-augite1111.1 1:111: 11'is .1:sometimes.111111I11'11111' .11'1-11highly 511111111111.zoned, 111111and 1111111111111111111'1'11.11.1'occasionally has 111111.“.faint .1111'11'1'grey or"1111'1'11111r1-1brownish gr‘uj.grey .'11111'1zones 111.1111near 1:1:the 1.111.111.centre. .'1'1:Sphene1.1.11.1 111'is 11'-11'1'1111'111common .1as:1 1111'"euhedral1.'-'.'..1'111 1.'1'1'1'....1'.crystals, 1511'singly'- 1'11'..'1.111..1.'1'.1or in clusters, 1111.1.one ..11111'.1'.11'cluster 111-11111111113:including 11a 1111.11.11.11.111111111'31'11111small irregular grain 1:11of perovskite,p111'1.11'1111-'11. 1111.111:while the:111 1111311111111melanite 111111111111garnets '.'.1'1:are partsp111‘11 1111'of 12111111111111euhedral 1.':"_-.'.1'11111:.II11111111111.crystals, zoned, 111.111and 1.1.1111with 111111.111111'inclusions 111'of 11111;.11'1aegirine-augite111:-.'11:1:11 .'1. 11111.1and 11211.1."-nephe- 1111:. T111'g1'111111111r111111 1.111111111111111 '-T]I!']I‘."_||."- line. The groundmass contains 1111111111111smaller 11:1h1111cz1.sphenes, 1111111111.:1needles 1.1111and 111-1111short [111111111prisms 111of .'11:aegirine-1'.-J 111111111.augite, 11111.!and 111:}:1111111111-1'1nephelines 111in 1".-a 111'.'111'-11'1111'1'.1p11:near-isotropic 1.1-111111..base. ..r ..1 - .f'... 1(iv)1 I'~ ' .II-'1Melaphonolites{’.'IIIIIELL'II'IJ'I1'1L11': '51-" II IILI {I ". Mafic.‘1-11111.11 lavas11111-1111 classified13111111111111 as111' melaphonolites111:1:111111111'11111111 1111312111occur 11111among1111I'1_.1 1111:.the T11111121'11'.Tinderet 111111.111.11.r.11agglomerates two'.'-.111 [1111.1and four11'-1:1 miles11111111.south-east:1111111— 1111111 of1.11 Lessos.1.11111111—1'111:The first1'11'1’1 (34/287)1.1—'1' 311.11 is1.1 11a fracturedII111111IL11'13'11 blue-grey..ILIE—grcg; rock11.1.1111. carrying13111111111151. numerous11111111111111. dull1.11.111 111111111111]euhedral 1111:2111:augite crystaJs1111111111. up11p 111to 3.'1 rom.111111. 1111111111.across. InI11 thin111111 .11'11'111111section the1111: 11121.11'1E1augites 11.1.;-are 1'11111211seen to11.1 111111:have pink titaniferous1.1111111111111111; 111111.11outer zones.2111161. '..-_I1L111'161‘11Clusters 11fof 111211":iron are111'-1: 111111and apatiteapa111e 111:1:111'occur '.'11in the1111: interlocking1111.:1]..11:L:1ng groundmass11111111111111.1111. 1211'of 11.113.111.11.augite, :111'111111111'1-111'111111-111carlsbad-twinned prisms3111.1111111 111111and 11111131111111irregular1 111-11111.1:crystals 1.1I'of 11111111111111.1111.orthoclase, 1111111iron 1111:are 111111and 11111111111111:probable nepheline.1111;111:1111: . 30I111 The etherother 1111111111111.example, 3:112:1134/251 11111-11from four1‘11-111' 11111e11mites 111111111—e1111'1south-east 1.11of 1-e.11111.11:1-1Lessos is tephritie.tephritic, has111111 11.11111:pale 11111111111111yellowish green 1:1111edr111euhedral 11111.1and partly1311111111 111111111'1er1rounded p11eneerj1'1'1t11phenocrysts 1.1t"of 11111-11111augite 111of 111111111111;varying 1111:1211.sizes, 111111and 111thhe11r111subhedral 111111and 111e1et111skeletal 1.111111111111111crystals 111:of 111.111iron 1.11'e.ore. Sphene 1311111111occurs 1111as large11111111 1111111and 111111111small e1111e111'111euhedral phenocrysts,11111.11111erg1'11111. 111111and 11111:1'1'1p11e1111111'1'111'11microphenocrysts 1.11of felspar111111111111: 1:111111111tconsist 111'of 1:111'111h11d-t1111-11111e11carlsbad-twinned 11111111111prisms 1'11"of 11111111111111.1111orthoclase 111111and 111.111lamellar-twinned111'1111—t11'11111e11 p1'11111111prisms 1.11of 11111g111111111111.plagioclase. 1111.1The 11r1111111tprismatic.p11-11111'phenocrystsr1-11111 111'1:are 111'1e111111e1'1orientated to111 1.1.111'1'give 11a hint1111111 1.11.of 1111.11.11flow .1'1tr11et11re.structure. The gr111'111111—ground- 111111111mass 111.111.11i1111'1consists 1'11of 111111111111111re1'1'111ge11'1a weakly birefringent baseh1111e 11111-111111largely 11111111111111.1111composed 1'1tof 11ephe1111e-er:1111111e11nepheline, crammed with1.1111 laths1.111111 1.11of plagioclase,p111g111e|1111e rodsr0111; 11111::and 111111.111short 1:11'1111'1'11'1prisms 111"of 12111111111111:pyroxene 11111.1and g1'1111111e11granules 11'"of 111111iron 11'-[‘13.ore. {111'-1:1'111'1119.Overlying 1111.1the pht1t1111it1ephonolitic 1111.1anep11el111'1emelanephelinite 111in the upper pertpart efof the 1111-11.lava 111111111111e1'.sequence 111111111there is111 :1a 111.11111et111edistinctive felsparphyricte'11p11111111111. 11111111;rock, which111111.11 131111111131provided 11pee1111e111specimens .'14___1.1;';.1'_'1.34/366 from1111111 1.1.1111two 111111.111miles 1111111h—11'e111south-west 111of 13111111Burnt F11re11'1.Forest 111111and ”1-'111"1""1'134/252 11111111from 1114t 11111e11miles 111:11'111—11'1'e111north-west :11of Nabkoi“1111-1111111 j1111e111111.junction. The 1111:1111111111111111groundmass provesp1'11'1-'e11 111e1111111'11identical 1111111with that111111. 1.11.'of the1111.1 11.111111111111111:phonolitic r'lephelir1jte11nephelinites E11111and phono'liticp11111'11'_1]'115.'-' 1'1melanephelinites1e11111ep11e11111le1'. 11'111e1'1which undePlineLJ11111:1'_1i111'.' 1.11111this 1111:111p11111'11111temelaphonoIite 11111.1and l11111-1:have 111t'e111111'already been 1'1ez1eti11e11.described. TheThe 111111i'1'1.matrix met-1111111contains Etee11'111eeL1311e.11ephe1111e.aegirine-augite, nepheline, felspar1‘1:- 111'r1111'1'111prisms 1111111and 111'-'1:11111111111111'phe111':.-'1'h1.1occasional sphene. The _phe1111-1'1'1'11t1'1phenocrysts :11'eare e1111et1t'1'11euhedral 111'or 11111111113111.1111subhedral nep11e1111e1.nephelines, occuring.11':1.'111'1111:'-_r singly111115-31}! or1'1r in1:1 clusters,elLI11‘1er11111'11'1and aegirine-augite:1"1-1111'11: 11111111: 1111'as euhedral1211111111111 or111' partlypart}; resorbed11:1.111'5'.'1.'11 11131111111zoned 1:111:11t11111crystals 11.-'1111with eegirineaegirine 111111-1111.fringes. 511-111-1111:Sphene 111is 11a 11111111111111common 111:1:e1111er1'.accessory, 11111.1and 1:.1tte11often 11111111e111te11associated '11-'1t11with 11'1'111iron ere.ore. LargeLerge 1'.-1111e1Jz'111euhedral felspar1111.11.11.11 1'1'1'1111111.crystals, up1111 11.1to :13 3.11111.cms. 1111111..long, 11111111show carls13111151111111bad 11111.1and anorthoclase11111.11'1111.1'-'1.111'.1: twinning.111-111111113 Someheme are1'11'1: marginally1'11-11911111111- resorbed,1'1'11111'111'11. displaying1'.'1i11p§11j1':'11g a11 zone111.1111: 111of inclusions1111:11151111111 111:11rnear the margin.111111111111. - 1'" '1 . . - 1‘11(v) Melilite-'71'1're1'1.-’.-'T1:' 11'1'11'1'3'111'1'1':1-.'.-'.-1"'.11nephelinites 11.1111Irand melilite111-1'1'1'1'1'.1.'""r 1.111151111-1'.'1111'1"1'1.-1.-11'.1melanephelinites...... _ .'.. '._'1 In111 11'-'1'111'1-11several placesp111ee11 1:11.11.east 1111.of Lessos,i.1:11.1'-1"11. in111 p111't1et11111'particular [t1in the 11111111111valleys 1.11"of '1111the Nderaguti."1111e1'111-111'11 11111111and DaragwaDt-trflg'e-e rivers,1'11-"ere. a11 111111thin band1111111 111'of 1.‘1.-"1-1'1:11.11.'tcompact blackL1|11e11 lava1:11.11 '.1-1111111:forms 1'1a subsidiary111111.11: 111111'1' .1e111111'1:feature below1113111111 the:that 1'11of the phonolitic[:11'11'1111111111: 111'ph1:11't11t1.'.nephelinite. The1111.1 distribution11:11tr11'1t111'1.'111 1.11:of 1111.1the [1111131111111mapped 1111113111111.outcrops 11111ee'1111:suggests that the 111.1115-flow 111.is 1'11'1'11:-.1L11'1'probably pt'e11e11tpresent 11.11as 111.a 111111thin 11111111:sheet 1111':over 11a 1':1_'11"11'-'11.'1et'11't'11econsiderable :11'e'11.area, though.h1111gh 111111111often giving1.1511111; 111.1no 1111111111::1111:1.'11t11'.'111.T1'1e111111;:1111'11.1_1-'11'-'11ie111111'surface indication. The rock is locally vesicular 1111.11and 1:11t1t:1i.r:11contains 111111111small 1.1-1.11.1111-waxy |.'.1111'.11'11.11'.'1'1'.1t11.phenocrysts. 5e11|1ere11Scattered [11111111111111.1111phenocrysts 1:11'of ele11'1'clear nephehttenepheline :11'1:are prL'1'11'1'11present 1'11'111and 1:111:111'131'111111occasional 11eg1r111e—1-111g1t111111.aegirine-augites. In 11p111'11111111111speciments .1134/28021111.1 11111.1and .’11-11128.134/283 the 111111111111melilite 1.1111111111311111phenocrysts 11:1'11:have been 1111111111:almost 1:11:11te1'11te11obliterated 1:113by 11111111111111]alteration 11:111and 111in '.1—1"211—134/244 1111.1are pre1'1e1'11'e11preserved 11.11as .-1'reirregular111:1' resorbed1'1111111'1711'1'1 crystals,1'11-111111111. 121113111121:giving 111111111111111111.anomalous, low-order111111-'—111':_1e1' birefringence111'ef1'1111'11-1111'1' 1'11111ur11'.colours. The1111:- 11.1111111111-.1.1groundmass 1.11is er1111'111'11'11crammed '11-€111with p1'11111111'prisms 1.11of 11'e11111'1-'weakly 1:11re11'birefringent111311.111- I'.1!t'1et'1'11mineral 1'11-'111'1-with 1'1'1111111e1lrounded .'111-11and 111:11111111111'11hexagonal '.111'1'111'1'1pieisotropic 11eeti111111sections 1p1'111'1111'1111r.(probably nepheline),-'-1:1he1'11e.'.11ee1.11e1'1needles 1.1111of aegirine-augite,1e1.'-'11'i11e—'1'1 111'-1111:. 111:1”:1111flecks 111of kataphorite1:111:1p't'11'11'111' and111111 111111iron 11111111.ores. A.’11 111111111111melilite nephelinite11ep11e11111'1e 1.1—'1(34/114)11111 of111 rather 1111111111111different appearanceapp-111111111121: 11:11:.was found11111111 in.511 .111an exposure.'.11111'111111'e 1:11of 11a 1"1:'111-'1.-'.11'1111few yards extent 11111111111:among the 11gg111111er11te11.agglomerates, 11111111three 111111111miles .111111'1h—1'1111:south-east 1-11of Kapsabet.'11-11511111111111. It11 1.11.111111could 11111not 111'.-be 111:1er111111e11determined 1.1-111:1herwhether 11it is11 1111.an 11111111111:intrusive 1111.111.rock. 1111.1The hand-11111111— specimen.1_1'.:11'111_111 111is 1-1a 11'-1131111311fractured 111111light 1:111:11!grey 1'111111rock '11-'111'1with r11111"-1.11'11I.'1-:numerous 11r.111|1'small :11111:er—1'-'1'.111'.1'-.1re11amber-co loured phenocrystsphe111.'11:'1"_1.11t11 1111-1111with 1'11L11'1111111rounded 1'11'or p'.'111111'11ti-'prismatic 111-11.111111'111.sections. {-111On 1113e1'11111'11p11microscope 11.111111111111111.111examination -.these111111; '1-1'1'eare 11e1':'t'seenJ. 1.1.1to be1111 melilite,11.1111.-. efteeoften partly11111'111' resorbed1e1111'he11 11111.1and in111 1711'11111111111:prismatic sections11111111111111 1:1;1'1'1-".11_1-_11l:111.carrying inclusions1111111111. 11111111:1along their'.1'11e'1' median1111:1'11111' line.11111'. Small1111111111: fresh11111-11 e111'1.:1.11':11euhedral nepheline11111111e111111. phenocrysts1111e-.11.1-.1.:"1.'1111_. occur11.1.1111 11'-1111';singly 1311-or ini1;- .:11.1111.-.'."11.clusters, in111 an1111 indeterminatein111'1e1'1t1111'111e' murky1111111'1:1 1:11'1'_111111111111111groundmass rich1'11-111 in111. 1r1111iron 1'.-re.ore. 3113;111-1133Specimen 3.1.11334/113 111.1111from 111-'1:1.111111'a similar 11.1p1111111'eexposure 111"of lava1.1111111 1'1a 1.11quarter| :11 1'11-11' 1.11of 11a "'1'-emile11...... 1'11to1.1. 1.111:the . ..11 .'. -..1 . .-...-. .-. -' .1. north1.1111 11.] is1111 51a pale[.=1.-1. Lgrey1111.11 .-.1-1.rock richI I1.1 in11 ferromagnesian11'1'1'1111111gt1e1.i:111 prismspr1111'1111 11:111and 1_.'1.='111.--.'11proved 11:1on 11'-111:11':-'I.1-1'r11'.-inspection to111- be1.11.1- 11a- .melilite111e1111ter-l: melanephelinite,n11..11.1-1-11..'|.:1.1-1.:- --I. I -.. with'11-1:11-'.1- -'resorbed1:1-1111111.:.|. I .'-:1.1:11:11zoned 11131-1.aegirine-augites-'I 111—111.11.111.11'1 - I' I -"1-- 11-111andI1- 1' 111altered1:11'|."' .'111 nepheline-.11.11111111111:-[ -." 111111.and-. melilite.1111—. ..|..-1-.'-'_TI -' 1 . 1 '1- ' - 1‘ .. Ir-I 1'1-.111111111e-r1-11Pyroxene-richr-"- :""' lavas1.1-111.11.i R" - 1.11.1.1-11occur'5‘" ' 11111111111111}.indifferentlyI 'II':- " '-"" - exposed1111111111111 westI11.1.11:'1' 11:-of:I- Lessos,11.11.111.11. .1111.and 1.11.11.1_._1.;several 11111er11e111111=superficially 11:111111'11'similar -".'_1'.'1:'.111types 11'-erewere 11111113.:11-1111'111mapped as 11a 1111111111single 111'1::.unit. .1.1-1.1.'"11'Specimen "11'1-34/2352.15 1'1-.1111from near111.1111 the1111:: Roman11111111111 11.1111111111:Catholic 11'-11111111school is111 11a fresh11111111 1.1:11'11‘dark grey-green111'- _1.-'—g 1:13:11 rock,T111111”. 111111with lustrous111.111'111111' ferro-1‘1-1:111— 111111-1111magnesian1.111111 1.1 phenocrysts.p e1111'1'11-11111- '1'111111'11These prove111'11'1'e 1.1.1to '11-11.be 1:colourless11.111'1-1-111 111:1to 1111-11:pale 11'-1.111111111111111yellowish 11111.11te11.augites, up111.1 1131to 1'18 mm.111111. 111in 11.11111111.length, 1111111:some being£1111; Idiet11erp111eidiomorphic 1..1.-'h1|1_1while 11ther11..1'1reothers are 11.11111e-:1zoned 111111and 11111111?highly t'e11'e1'he111.resorbed. PerovskitePerth-1111111: is[11' 31111111111111abundant 1111as large 1.11111dull 1111111pink 111L1111'1E1211-1'51!subhedral 151'111'1L111'granules, deeply11.111'p1_1.-' er11e111111cracked 111111and 1.1111131often 1'1-1thwith 1:11.11'e:~1cores peppered '11'i'11'1with 11'111111L1:minute inclusions,111e11111'11'1t11'1'. 111111and diepleyihgdisplaying 13111113111typical 1111.11.11—cross- hatch111111111 twinning.111-1111111111. .'11-'1e1111te1:Melilites 11in 1111111111plates up to111 1 mm.111111. in111 1|111111e1e1'.diameter, 1111111et11111'111sometimes with11'1th median111e1111111 pi 31 eraeltscracks and alteratienalteration parallel teto the e-Iisisc-axis giving a resemblaiieeresemblance ttito peg strttettire.structure, and seatteretiscattered small nephelines are present. MagnetiteI1.-"lIIgr1etite tieetIrsoccurs iIIin er31stalscrystals and grains tit"of 1.1arIt'itisvarious .si'.1.1.essizes tipup to 1 mm. diameter and stimetimessometimes inelatlesincludes small pertwskitesperovskites aiit'land atethet'sat others is iIiel'tttledincluded within the atigites.augites. 'l'heThe gretiI'Idmassgroundmass is etimptisedcomposed e11"of atigiteaugite prisms.prisms, ahtiiitlaiitabundant IiepheliIienepheline crystals, pereirsltiteperovskite and treeiron areore aridand ineltietesincludes large elear‘clear patchespatelies IiIIof IIIialeimeanalcime aridand le-eallocal etineeIItI'atitirisconcentrations tIIIof green.green alteratit'ir.alteration prtidiietsproducts asseeiatedassociated with thethe melilite. {1'i}(vi) I‘vfelititttesMelilitites A11I'1 paleF‘slII? grey£3.s fracturedIII‘flIL‘ILITCEI rockreek {34:'I.-.11.3l(34(233) formsterms aa. pronouncedt1I'tiIiIitineed litInirt'Ie-elt—hummock-likeI: It exposureeshtisdre miningamong the tIggltiiiieI'I-Itesagglomerates in the liedbed {IIIof tehthe I'ii'erriver eiieone mile stitith—westsouth-west t‘JiI.of KiKibebet.hehet. :1.A stilitat'31solitary lai'g'1large hieititebiotite 31e11.i.r1stphenocryst is 1.1:sililevisible iniI1. hand-speeimeiihand-specimen and a greenish .te:.'rt'.1-ferro- ."Iiagriesiaiimagnesian er3-1stal.crystal, 1.1..l1iehwhich pI”i-1.t'1.elproved IIIto hebe elis-irie.olivine. Inin thin seetieiitsection the reel:rock displays altered remnants tilof iiephnepheline'11 phephenocrystsI1ti1.':'31sts iIiin a i'iriesgrainetifine-grained gi'tiLIiitlniassgroundmass et'aritrrtettcrammed with small meliiitemelilite er31..1..1crystals t‘-IIof etihedrs'euhedral shap'.shape. .atigiteAugite pheritier3-stsphenocrysts are aslalsoti pI'I'Iesepresent. :‘1-‘ii(vii)I ITIII'IIIIIIIIIs'Basanites A.1511. series t1|Iof hasiebasic las'ttlava Iltiwsflows entered the area .1'It't'irrifrom the ili'JllliIsouth 1tat Ita late staeestage iiiin the Tiiidei'etTinderet s-IIIeaIiieiI3-1volcanicity and isis newnow esteiisi1.-'e|3'extensively esiiesedexposed in the h-Itet'eiMtetei 1.1alle1_-.'.valley, dipping titat tippi't‘isirt'iatel3'approximately III10° IIIto the 11:1tnorth te1.1.-'I'I:‘dstowards the footlead tilof the Iigglti..iet't1.teagglomerate 1....-IIscarp.1.1.1. SheeitrienSpecimen 34-533934(339 l'Irtirrifrom the "1-'lteteiMtetei trailet-valley rtiatlroad at the eI.1_ttattir.equator, is a linefine-grainedIll-airieel slat-.1-slate- gt'e3.-'grey reekrock with heartoccasionals.iririal s-es:vesicleseles part-filledpat't— Ill; ett w-with1h eacalcite,leite. and earI'3-'iI1.gcarrying larlargerge p3-1I'eitertespyroxenes and rather smaller altered tili11ineolivine phenocrysts.phe Iieier3'sts. InII1 thin sesectionCtlflltl tlieIthe olivineilis'irie givesgis'es es'ideiieeevidence IIIof titwo periedsperiods t‘IIIof grtiwth.growth, with slight IIlIeI'tItiIinalteration Itito iddingsiteitlrti tigsite at the interrnediaieintermediate 1state.state, while larger ironii'Iin tireore grains di:displaypla3 highl31highly I'e'I':-I'l1ietresorbed enitie'tieidamoeboid shapes. A.51. mesh1.1-est I1ItIof laths tilof plagieelaseplagioclase tiIIof ti'titl—IIIhz'tIdIII'LIemid-labradorite 1.1tii‘ri3iesitcompositionfitii1. are present aridand a lIeliIIthe-Ltifelspathoid t-‘IiiiierI'II.mineral, pi'tihahl31probably Iianalcime,IIaIe'I11"te.1.1eeiit'soccurs iritei'stial|3.1interstially irtin the 111t1ttt1.'1t‘1groundmass. A.41. similar rockreieit {34.33.13(34(320) ti'tiiiifrom the eastern Iritieefringe IIIof the Ileisssflows showss'_:'1ti-.1.'s 'large.e I'ge euhedraletI1:1..11.lt.1..' atteites-augites, rtitineletlrounded pseudomorphspsetitleimei'phs atof allolivine1.1 iriin serpentine minerals,IiIierals. Ielspatheiid-Iiitiseiefelspathoid-mosaic patchespatehe.s alterafter nephelineiiephelitie and Iihtitit.ttt1.tabundant labradoritela II‘iIittdtit‘iIte microphenocrysts.t.11t..11[.iii-'ttiet1.sts A.13. meliliteIi'ielilfte basanitehI-'I.1I_I1I-..i1_..1 I.3—I_'I32til(34 (326) lrt'iti'ifrom furtherlur'thei' rttii'thnorth earriescarries perfect,perteet. lteshfresh eithetiraleuhedral atigitesaugites aridand tili1-':I.-Ite.1olivines (0.815.0.3 cm.)11:111.] and highlyhighle corrodedet‘irt‘t'ided melilitesri'teiilites stirrtittti1surrounded.led byI313: fringesIIt'itiges oftil fine-grainedlirie—giIi.iI1.e=.'i alteratititialteration products.pI'IidtIeIs. Part-resorbedF'at't—resriI' eed hepht.nepheline1lirie reiiir.aii'.remnantss t'Ieetiroccur and t'rtidecrude 1'.-31‘11'1'.spherulesIes .11of .Ieeil:zeolite.te A.11. small flowIlew t‘ii‘Iof etiarsei1-eI3-'stall:iiecoarsely crystalline hasanitebasanite (34(338)3-I_. 381 termsforms Ita hill tineone mileniile northhart-.1. oftil the end oftil the MteteiT‘s-'Iteteisvalleys'til.e3.-' road.rIiIII'j. Here hethboth the olivinestiIis-Ines and augitesatigites exceedeseeed 1I em. titin length. The atigitesaugites are etihetlraleuhedral htitbut slightlyslightl3-' roundedretlt‘ided while1-.1.hie the tili‘1-'.'r‘tesolivines oftentilIteii showshew fresh skeletal etires.cores, while riiiertipherttierestsmicrophenocrysts ttl'Iof plagioclaseplagitielase ant.and felsparlIe.lsI1.tii'pris1:tprisms inia the groundmassertitiridmass are lamellar-twinnedlamellaI' twinned and havehas-e a eI1n'-.riI.1.sitiI.1.r1.composition withinwith: .-1 the labradoritelIIh1'atit1r:'t range. II'III(d) Ir-li-IIIIIIIIIIPhonolitesII-1.-I1 1. r_1_IIof Tinderet.i'IIII'I.'£t'iIt’i"E’.I ClttOn the higl'tes'.highest grtittrttlground in[II the stittth—eastsouth-east part tilof the at‘et'area a seleet'.I1iIiselection tilof lavaslat-as III.of sariitirilevariable tippetit‘atiee.appearance, htitbut t3-‘t1ieatypicallyll3 withs-ith phonolitehittirtt'ilite composition,11'11I1.111.it 1.1.1111. hilt-1.111131outcrop ttigeihertogether with .1.til.‘it.irdi11iatesubordinate ttIliIstuffs and ashes. Lorokil.tirt1l'.i hillitill is eaprietlcapped h3-by a porcellanousp-i_1.1iii1t. hitie—hltiehblue-black lavalash I.II11_T_‘It:‘.t'."it"I'.t.‘.l'|._1.I11-I.-(specimen 34(347),. sparsely porphyriticpti:'_1.1I13t'itie 1.1.'ithwith tie-easierialoccasional glassyglass3 felspars.Eelspars. lheThe phenocrysts3'Il'1e11tier3-'sts 1.'t.=tcut lIE'Iin a.a the".thin seetie-I'.section 1.1.1et'ewere I'Iegi'.-t1.e-.-It:g:teaegirine-augite and iI'I1:Iiron tire.ore, while the hltiieligi'blotchy grtiIII.1=:l1.1.1.IIssground mass 1ie't1eeeincluded aegiritie——I-1.II.1_Ite.aegirine-augite, I.at.11i..I.Ikataphorite,te Ielspet'felspar and stiitiip31stumpy prisiiietit'prismatic tie-pheliiies.nephelines. .11.A much.11.1.1Ieh r1.1.'t11.-.1more eIiaI'sel3'coarsely ptii'ph3'1'itieporphyritic plitttieilitephonolite I31—Is'I.I1Z.'i'_l'i(34(353) mapped '1'1'Il'I3lI‘:within this gretipgroup eepscaps the hills :11at the-.h.'- ( estreri'ieextreme easteriieastern end tilof the Mtetei1‘.-'ltete'. valley.1.':.IlI.1'..l1It ear1'iescarries eIiIisiiietttitisconspicuous earishIId-t'w'irtitetlcarlsbad-twinned glassy I.I' felsparIIelspar crystalst'I'3-'staIs and fewertewer smallersri'iallei waxywar-1.3.1 etihetlraleuhedral nephelinenepheli ne prismsprisms. 6.3111tamtiipiitsrts6. Metamorphism tilof the Basement ‘1i3'slesi1.System It is geiiei'all3-1generally aeeeptedaccepted that theltie rI'ielIsrocks [tilof the Basement.Basement .3-sten1System I1I.'of Islert31aKenya have beenlIeeIi deris'edderived byh31 regionaJlregieirial metamorphismmetanitirphistii aridand granitieatitihgranitization fromErI'im anati rir'istiiialoriginaJl stieeessiensuccession eIimptisedcomposed eitof sediiiietitar31sedimentary reeks.rocks. ThretigheititThroughout ArehaeanArchaean times these rtieitsrocks wwere'1re prtihairil3'probably stthjeetedsubjected ttito se1.-'eralseveral phases atof injeetiettinjection aridand Itietat'rierrphemetamorphic alteratirm.alteration. . 1..' 32'.....1 1 Lacally1.1155115" 111in 11111the 1511155311111Kapsabet 1115'area 15-‘1111—1'1111111511well-faliated 111111'15biatite 5515155115gneisses 1111111:accur 11111but 511111give 1111111way 111111151further 51111111.sauth, 1'11.in 111.11the regian-5115 111'af 111155.Sayet, 11::to, 11151:mare'5 1111-1111highly5' 51111111111511granitized 15115151111111:leucacratic 1.11111111111—quartzo- felspathic-" 5.551111111': 111-111and 5111115151111granitaid 51111115555.111gneisses. In 1.15the 11::-1::11.-'narth, in51511the 11151511regian 111'af K11511-Kabiyet5'1 11111.1and 51-115111.Sangala, 1111an 111115115115extensive 1:11:15zane 111'af 51151111111155migmatites 111111111115;grading 1111111into, 511151155patches 51'af 11111111151111:migmatitic 511111115granite 551111111155cantinues 11111.aut 111"af 1111::the 111511area 111to, 1115the 1111-1111,narth, 1511515where 11311-715575Sanders has1155 111555511mapped 1111an 555115155exensive 1.1511belt 11:af .I 1.51111111111111.1111granadiarite 511111and 1'5“1-1granadiaritic'1'111.I'r'11'.' 11115111111111:migmatite 5111111111around Turbo,.11111111- Inin 11a 51155-1111chapter 111':an 11"11.I'.11111111'51"111.'metamarphic 1115155facies in111 relatian151-111-1115 111to, 111115111311.magma, 11115:.Turner'I: 11';11'-'."11.11151(Fyfe, Turner 11111.1'and "1'51111'1115511.Verhaagen, 11.15.11.1958, p._'1. 211':202) 11115515511515.5111has discussed 1115the 115-1511151511develapment:11 afF511::palingenetic55511111: 515111151granite 151.115.5155migmatites in111 11.111155zanes 11'1"af 111.7555high-grade 15511111111regiana1 111-5111111515115111.metamarphism. '1'-'15.He 5111151'1'1'1"1states that under11111115: these111555 51111111151115canditians 11'-.5111metamorphism111151115 11': 1111.5has 51111111115151?culminated 1'11in 5111:1151partial fusian111511.111 1.11'af 1111111rack I'.'1.111'1_camplexes5.1155 11'}to, 15115-1:give 515111111:granitic liquids11115-1125 15111511which mayr"1111" 51.111551111511115subsequently 111-11'":have 1:1'1-51-11-i'1'1111-11crystallized in1:1 place1.111155 {11'ar may11111111 have111155 111151111511migrated 15to, 5""11511111-samewhat higher115.1111 1 155515.levels, in111 511151either 511511case giving511111111 1'.-55rise 15to, 11111111151115migmatite 5111115151155.camplexes. In111 111115this 511111115111situatian 1115the 5:155"physical1151 canditians111111152115 51'af 111511111151'511151'11metamarphism 1.11-1115averlap 111115.:thase at'1'-=11. '1'-.'111'1'1which 515'1'111155granite 7111:1151melts 15:1:are stable5 111111and there'..-1515 1111.151must 1:15be 11a '15-'15:wide 1'1-1:155range 1'1'1'af 1511'1551'temperature1'1-1111:: 111111and 515551.115.pressure :11at 1'111'1'1which 1111:1'metamarphic511:1"1'11'111'. 1115155rocks 1111af 5151i:variaus1115' 155111115kinds -.'.'1111can 1'5-511155.ca-exist 1'.-'111'1with 3111111.:granite 111-111:5melts 111'af 51111511varied water115151 5115cantent.551. T115The 5511511111515sediments 1'1'11i5'1'1which 1:11an metamarphism1 1:51.111151: 111115111 5111111155111praduced 15':the1 1151111511banded 5111515555gneisses 111in 1:15the 11:51:area 5151:1151araund 151-1155111111?-Kapsabet 5'1'1'1':were 111"of '11a ”1'5-11"."fairly'l hamageneaus111-.'II""I.1:I15 5511115551111:semi-pelitic 1'111'11'11'variety 1111'.and, 11.5as :1a 1.5.11:—con- . ‘1"1! fled I 1,1” 1' .. ._., 1.... .‘.-1.". .3 -.::- fi'klhlr1|:"r1-l'!—i_"1 {3.1-1 5n... 5111"“1-'1. '_-'|._|.5_]L'L- {_I'ih:_._lillr -"."|::l-'|||.:-'1'[- .lIJl-lL-LJJ 11.'|1.."_""_"|'L'|. - _._|._:.I_. C‘LJ‘L" .1, sequence, 11111the 55111111515555paragneisses praduced5. display similar mineral assembleges.5.5""- The general 1151111trend 11..'.ILI"'I1'1.11thraughaut subsequent:5'11'.'5-1'11111'1'11 metasamatic1111:111s'1111'11'1111; alteratian:1111'1111'1'111111'af 1.115the 1115155racks has111-15 been115511 1111111111taward petralagical55111115515111 unifarmity.1.111111111111112 L515-515g5Late-stage 11111111155111111intraductian 111'af 11115111111515.1151alkali fe1spar 5115can 1111511aften be'55 1151551511detected 11:11.1and 1111':the mast1111.151 1'51'11:1'11'11.common mineral1'.-“1111:1511 11155"'1'11":assemblage 11111-511nated 1:1IS 1.11::1r:1'.—11'1.13111511155—1'1111311'1-511115-quartz-plagiadase-microdine- 15111115.biotite, 11111'5'anly 51111'...'=.1'.5155sametimes :11'151111151'1111511accampanied by1111' 11511111111epidnte =.'.I'11'1and muscavite.111151: .'115. Bath1111135. the1'55 1.111111latter minerals15111511115 may111115 be11511511111111produced 1111an :11:alteratian51:1115:1 51"af 115111115.biatite. 15111511Much :11'of 1'15the 1111:1111alkali 15155111felspar 111in 111555these racks1115115 15is paarly51.11.1115 twinned,1151111151.. 111111and it1: 1'5is notable5.1151115 111111that 51.11115.same orthaclase51111551555 was115.5 15511-1111recagnized.1111 1111111511thaugh micracline11115111511111: 1'5-1111':is the 5:511:31'1'1111111'11predaminant patash511111511 151115111.felspar. Dia'gnastic11311511115111: 111:11'1'51mineral assemblages55111115! 1.1115 1515are 1151151"better 111551111displayed51'] 1151:1111by the 1.1111111511515555orthogneisses 1551555111511represented 111'by plagioclase11111511111555 11.1115211111111151'115115amphibalite racks. T115The 1'1151'5'15rocks 111'of 1111'the 1115::area 111-5:111:15display 11555111111115.1115assemblages '15'1111111-11'111155115which indicate 111-'1:that 1115}:they must11111151 11::be included1515111111151 111in 1'11:the 1511:111'1'1'11111—stauralite-quartz1111:1115 1551151115115sub-facies 111'af 1111:the 1'1111'1111511111125:1115'11'11111'115almandine-amphibolite '1':11:1'1:-'-'1facies {1'5-'11:.(Fyfe, TurnerI1 11' 1151' 111111and 1"511111115511.Verhoogen, '1.-1:11.5-1958, p. 2"11'1.229). T111115:Turner 5111155.states 151111that 1:111the 15511151typical 11151111made 111'of 5:151:11:—occur- 1'.'I'.I::5rence 111'af 11115this 1:113:55facies 1.5:is 11':in 1115the 5115.111high-grade5511':11:!1': 1'1-11155zanes 1'11af 511'-pragressive":1'551511'1' 1'I:-_'-.'.-_'1'1:I:‘:51.'1regianal 11'15'11511'111151'1'51115—me,tamarphism- 115111fram the11111 111111-1115middle :11of 1115111111511the garnet 1:11:15zane 1111511511through 1115the 111111115zanes 111'of stauralite,5. 5111111115. 11111111jt5'11-11.kyanite and 5i'i'11'1'1:1sillimanite.1111':- .1511I.'|'.Racks.5 111'af 11115this 1:11.115facies 1.1'11'111'111'cammanly1.- 11111115grade into,11:11 T1111111..I1.L5migmatites 51.111551veined 15111.]with 51.-111111115:granitic 1111115111115.materials. 111In fact,111-'1".- the1:111: 1111115three indexi1: 11'1'15 51111511115minerals 1.1111111:quoted'11 1551::were 1:111not 11151.:55:1-'.'5themselves 15511511111511recagnized 11'.in the1111'.“ 1':area.F1311. T115The 11.1111faurth:11 mineral511551111 11.55assemblage1' '1-55 1111111511quated 115'by '1'1111151Turner for151 11111the 51111111111155]11511.1.stauralite-quartz 511b—sub- facies:':1L'i55 15is 1.1511derived51:11 fram1'1-'11'1'1 basic111-1:511: racks,'1'-1:15.5- :-111:'.1and 1.1”.is 1111I"1'harnblende-plagiadase-almandine-epidate1'11:— 555111 111:55—1111111111151115—1'51d1'115 (quartz-biotite).111111111-11'111"". 55551111511Specimen 35"1'1'5134/199 fram1'1'1'1111 one11115 111111and :1a half11111-1 miles1111515 narth1151111 of111' Chemnorwet{.'111'151111115'51 market1111115151. 15.(p. 18)11'-:1 cantains55111111115 these1111-155 faur1111.'1' essential555111111111 minerals111111511115 plus111-:15 1111:1111:quartz 111111and diopside.5111551115. Simi-1.111111- larly‘1:1115' specimen5511111111511 3151-"2'11134/208 1"1'11111from eastern5115:5111 Algabbyet1115111111551 15.(p. 17)1?] and11115] .11-411.134/405 1111111from 111-1'1trwa and111111 a half111111 miles,1111'155- 51511111551151sauth-east 51'af Kipkarren1111111151155 1111111551market 15-1111(p. 18) cantains51111151115 h:ornblende,11.111111115111115. p1agiaclase5155111511151: 111111and garnet51111151 111111and 51111111111155"dinozoisite in1:1 5111115place 111'1'51111511111'115af ferruginaus epidote.1'I511111I111.IQ11:1111115Quartz is common51111: 111511 111to, 1111all 111155three 555511115115specimens, while'51115 1111111:biatite11 is15 :11155111.absent. 5551;111:5115Specimens 35'1'1'1'1'34/199 111111and 3515—111:34/405 both1111111 1'1-111111111cantain 51111551115.diapside, and11111.] 11111151111therefare11: 5111115”shaw 1111111111155affinities 111to, theca1careous1111: 51115111511115 55551111111151:assemblage diapside-harnb1ende-epidate1'1111551d5511111'I1bl511d5-551d1'111: (1—-plagioclase).11.111111111515111 Specimen355111111511 351.51134/71 from1111111 a:1 mile111115 11111.1and :1a 1.11111half 11111111511151north-east 111'of K115511551:Kapsabet [5.1.1](p. 12) 1555was 15555.;—recog- nized1:11'.51'i by115' 111-1its field1'15I1-1 relations1511111111115 11.5as 11a metamorphased11113111111015111151.'51 1.15115dyke rack111111: 511dand 1111an 11111151111mineral 5511'5051111'11'1campasition .1155also falls11111.5 in111 111::the stauralite-quartz51115111111515.1515: 511111115155.subfacies. It11. containsE511111111'5 harnblende,11.111111111111115. plagioclase,5111515111555. 1151111115.epidote, 111111111:quartz 1111-11and 1111.11115-biatite. Specimen5555111151'1 31-15-111134/308 and11.1111 351.111134/316 15.1-11.1111111(p. 13), bath grailiitaid11511111111111 gneisses11115-15555 fram1"1'11111 51111111sauth 111'of Sayet,1111551. have111115 the1115 mineral151111111111 11.55::assemblage111111155 of111' 11111the 1111111151141:quartza-felspathic1551111115 group515115 1'11"af the1115 51111111111111—staurolite- '1'-1111-13quartz 151111'111'1'155-11'155'subfacies. They 5:151:55cantain 1.11111111-quarltz, 11115111511115.microcIine, 55151111311155.plagiacIas,e, biatite,b1111i11'1'. muscovite11111551215115 1111131and epidate.51111111111. r Iva-J 33'._..-.il III-II- 5: r . . . III E --" —.. . “I. I. III. I‘I +5 I__ - -.-. -__ I; . ‘II. II. I . III... . __HII- _--'I.‘I.II I. I‘M. "I- .'. .-"I-_ 'I. .. -. “II II. "' ._ 35'03' I I -. IIF - 'HH '\I -.. ... - I I II '\I K'l .-. EDT I. __ I " I, -. . _ 'I. I - '-I.__ '..'I '] I. ' ' I..- i :--. " _1' .: : . I. _- c If; ' -. iLdII'I'.‘=-_1I=.-..- _ I L _-r . .- .. I .- . III-J J-I.\_I_ ' ' ' " II; -" I1II"III - ' ..r'“ I_.'.'. In 'I..'I I I - -.....--_.I...nII . l. .I.. L .... 1. __ _ _ . E 3:12....- . .- _ I .I..r-._ . .- .I- I ._... __ ' __--_. I _ _ ..._. _ I. ' I I: ' _ _ {__. ._. I..._I.,I .. _I 1-. _ I I I II'I:I- .-I. III IIIi-I I .II. I' I-J.II.I_"." .1": ' _ I . ' __. . -._I -I- . . I! .'-=.=. ' - - - I ' .I 'I" '.I ! II'L 'I -I IIa 3-. - ' I | __ I'd-II . . __.-' II-I. ‘-' ' III I. I.\__.'--— I? I - I. .' :4.-- _ III”. h - ' I.'-.. I " . -_ 1 III: .IIIII. I r I _ I: I I'I_ ' ‘I'a .' '- I - - I I . I- _ _,.--.I I. .- - I ..._ I _ _. . I'I 1I-.I_- I. .- I r -I' __ I I I I _ ___,.-" I'II ‘I- I. - ,. .I . I II. I'- - II I I I IIIIII -' 'III I I I .. - - - _ . I- : . - -_ "' --.I1! .- _-._ - - '_ 'I._ I -I. ' 'II I. - I I. I. I. ' ' I i . .- III “I. I '- . : .. -- i '- -. If' 5.. I- .-‘I r ' I. .I-- I I . ' .'_.. . I '\-_-I III | . ....— _L.-.-I-I. _. -I——I———— ——— I I'- I: : .I "I. \ . I ' - ' ‘. ..-'. ' -_ -. - F I. '\I ' ' II I '\I I- . . I. . P“. III . .I I ‘ I . III I II- III. . E .. . . I. -. _I . II. I“ . I II. : _-:-' ' 'I ' '- '. . . II. .. -. I I.I -_ I'I . II II“ I. .I L1 _ I. ._ ”'I- 1. I. . ' . i I. III ' I F I' I I. I“ | . i ' II ' I. III”.J I- -- .II I. .I. _ - . I. . . _ I. I. I. I. . II. “‘I_ . I. .. . I. I . I I. II I. I. I ”K.- 'I. I I I“ I. I ! I. ' ' I' I. _ I‘M 1 I -. - . . _ ,I I. I. I. :. : ‘ . . - I. I II. I. '\I I II. III. II. I. | : "I ~ I-‘ “I I I . I I !II I. I ' I. I“ I __ 'I. I'I. "II._ _ "' I- I. I. . 'I_ 'I. I. "'I. III : “I. ' - I ' I“ 'I !_ .__ 'II._ I. . _ I. _ I. I I '\I I 'I_ "' "I I I III '1 I I . ._ .I . II. I. . Ii ”'I- I. III II. I._ .I I. 1 . I.'I_ - "'II. III I. . “I. - II I. I.. II I '_ ' .-' '. _.-I"' -' " III' III" " " . 1. - _..-"'III ”I“ I I" - -' '_ _ (I - "III- I' . I III . .I _ '..-"I - _.-' ' ‘- .I’ — --.~I' 315. " I“ F" __. LI.._ ._ . \ ' : I. r'II II .I ' .- ..I' ..'- ..- .91..— ' -. I“ ~. I. -_ ..I-I-I-"III I _' -' _-_. . ‘i- .- . I-_ " 1" ' ' . II '- .._; ‘ LI" 3,. XII ‘ 'II. . I’- _.--’#-I I“ ‘ .1I _I' i I I_.I"I.— . _. . _ -- ____-I"I _ _ _ ' ' ._ __ _.. "I "'- IIIII“ ”I I III'II. E-Ii;r. LEI—Harts: earm- Er-I iii-II. HIIIIz-IIILIIII .‘Iig'IIiLIm :“rcf.I If." fin. . 34 T.7. StruetureStructure {l}(1) BASEMENTIHHHFHH'EH'I' SH'H'ILHHSYSTEM The.The BasementRHHen'leIEt SystemFly-'Hiei‘l‘: gi'leiHHeHgneisses ofel~ the areaHl'e: LlalaH'display a2'1 1'eginn;1|regi0'nal Hirikestrike ill:of N.l‘H'.‘H-‘IE.-N.N.W.- 35E.5.S.E. wizh.with Hleepsteep dips{llpH telto Hhethe nertlE—eL-EH:north-;east ll’ig.(Fig. Bl.3), embut in[:1 LH-Hetw0' localitiesleeELlilleH 1hthee biETlHL’strike HHH-‘ingHswings mare.more nearlyr1 ‘[.i_['l:'-' T‘H_T‘~I.E.—E§.S.‘-N.N.E.-S.S.W.fir’, with1.1. ltl‘l emreHeendlngcorresponding HL‘ELJ‘Lh—eHHlerlysouth-easterly dips.:iln. Inln ilEethe Eml'lhnorth the I'LCEH'Hrocks have been Elll.El'lCli;*l"LIl}'sufficiently mel‘lllieedmobilized l0'callylneHllH 1e:to US$31.13:destroy 1h:the eriginaloriginal gneiHHHH‘egneissose foliation,lullzlllun. Huellsuch fabricslEillll'ECH El‘Has neem'0'ccur being the remitresult of Hmitedlimited lHHeplastic lELl'H‘.'-flow. Furtherl“. .l:rlhe.‘ HUHLiLsouth, nee."near habiyet,Kabiyet, the l:{']ll'.';lll;}l'lfoliation alipdip in.in the.the migmatitesI'f‘llgETlLLlltflfl parallelsI_'.“-LLl'i.1El|E‘lr-l Ellethe Llll'rdip LEI"of the1h” Aigabbyet.-"nahh}e1 EHE‘Etel‘EEEELEIEleamphibolite n-‘inggiving .51a regionregime- .nl‘of :'H-.2I-'_1El']~H'H-E'_'HEL'I'l}"south-westerly dips.IL'lEETJH. :1.A Htr‘lleestrike HHHnswing In“:t0' Ela THEHJE—SN.N.E.-S.S.W.fif‘fi'. trendII'eflLl EHis H-‘EHil’JE-evisible forlei: Hemesome HlHsix mileHmiles ne'ernear HE'l‘Ee'rnLLH'HH'H,Chemuswa, and L':a Himilnrsimilar l'eliilllnnfoliation llieestrike lHis presentpreHent in the rocksreekH ofel' ElLethe hillsI'EillH :11at the f0'ot[em at"of the l‘H‘H-ende.Nyando EHEtiEEp.scarp. lnIn l'millboth eELHeHcases the l‘nlEHEim'Efoliation {15pdip EHis moderateI'I'li.lILlCl';il_C and mto .l'lethe HL'Eih—“H'south-east. Locallyieellll} l' ...“; . .- . ... .- q: ..1'- ',. ...J' ..‘ _. ‘ . ..‘ .....b. -. -i-. v... :I.11-...-.Lh.tn.1Hlineations .ne.are matnot Haulwell .Ea_.;H.-.L.displayed min ll-H.the “Eel“.rocks ellof the:lu. EMHE-area, [mtbut 'H"...i._|'...where Heenseen 'H’J'P"were..re H-‘EEI'Ellevariable | F'_ r' .. . ' li'lin Llaz'ee‘lll'mdirection lT‘nL‘lbetween". H-een “Evil90° 54.11;]and E")?192° mm!and in plunge betweenl‘IeiHHeEH 3.“-350 LEElL'E'and 75°I.“ t0'H"! the.l'!|.'.‘ ‘HHJLlIE'I—south- eEEHteast quallmniquadrant ELI-lb.(Fig. 3). N “:1. 'H. -H--._+._...'...... H_.._ PT“ "1. " -' I. 00 H 0 -—L 0 -H;._ _----—.._ E ' "" .. Hun-‘1.- .= lineationLEHEBUGH Fig.Fig. 4-Stereographic4—Starermmphie projectionllrfljeetifln {1fof pnleHpoles tom felietienfoliation 11mland lineationlineutinn forfur the reeIHHrocks efof the HuHementBasement fiSystemj'em in the are-.1area araroundflunrl Kapsabet.HuluheL PnieHPoles tnto frlliatiunfoliation dens-zit}density enntnurHcontours at 2 per cent, 38 per eenicent 11ndand 16lfi per cent [112(122 medium!readings) """'" 35 All infertnetieninformation enon the dip and strike elf'Of[eh-Linenfoliation and the direetinndirectian endand plunge eifof lineetitinlineaition ofeat the gtteieeeegneisses efof the BasementHeeement SystetriSystem is ehewnshown nnon Fig. 3. The etytestyle enttand tlegt'eedegree ofet' foldingEmitting tier;was netnot ehvietteobvious in the fieldheld and the evidenceevitienee eenHeeteticollected it;is not"tCJT enn-con- elttejie'e-clusive. ’I'heThe followingt'ellee-‘ing etiggeetienssuggestions areet'e ttzereftiretherefore tentative.tentative. InIn the area tthetitabout KapsabetKeLtTIFttij-Ett the gneiaeesgneisses areet'e iseetitttttiyisodinally foldedt'eitieti aboutEtiJDtEt near-verticaltEE't'tF-tet'tir'ti axial:txitii planeseittttes enttand tit-'erl'ti'tttittg.overfolding, where it occurs,EJCC‘LH‘S. istr; totn the west. LineationsLitteetithts~ atggesuggest that the foldteit'l ttiteeaxes tt'etttitrend H.H-1‘r".—S_S.E_N.N.W.-S.S.E. ttttttand plungeplenge steeplyeteeei}! tote the hilltTi‘I—Ssouth-south-eastflttlil-ettfii atet ehtitttabout 66°t':-t’-' (Fig. 3i}.4). '.i."i‘:eThe onlyeniy minorrninttt' fold-structuresi'tild-ett‘ttetttrert Teetignieed.recognized, 3-}3t milesnttiee south-eastHflLS’tit-E‘fiii tit"of Kapsabet,Ktieetttiet. havei'tEthC‘ eaten;axes in planesnienee parallelgei'ei e| teto the enielaxial planesplatter-5 ei'of the majormeter folds,inf-tie. hetbut pungingttttttgitig at t’tti'60° ttneiand 70°7121' totn the north-north-west,ttDt‘th—tttit‘th—iieeL i.e.,i.e.. the minortttit‘tt‘it‘ foldt‘t‘iiti ttrteieaxes antiand regionalt‘egitinei lineationlineetitin intersectit';tet~_;eet at (:U60°. N I _—— _ _ -'_‘——_ - __\__ .-" .-" .--'" __.- "’2. .-' -""" /- IE / . H. r' . 'H. . —\-'—\_. 'L -. "' Uni-“'5. .-' If 't.‘ “H. a. ' "H. . '\. I 'I .- {n . . .'I -_ M E.-.r . _ . .-_ he . i _ __..._l-' H t .-"II .r . .- .-' F . . .. ' “Ru—LP“-'I __.-"" ' .-' It.- I" “; .=-"' It." / MN. I}; .I' a 1-. - e _ If"- ‘1. ._ .-""'- H 'H. H... -\.J_--- ___.-"'-l -----I 5 ___e-due-”H ______- ___ __ 0“ Lineetlenlineation Fig.Hg. 55-Stereographic"EilerEt'tgnttJTtie gt'njeetitmprojection iiiof [Jpolesfllfl'li tnto fttiititittnfoliation tint]and littettlitinlineation ferfor the meter;rocks HEof thethe Basement“nee-teem SyetemSystem in the HTEHarea :tnmnelaround Kabiyet.Kaliiyet. Pei-er;Poles to[u fittittlittnfoliation fidensityeneity eentmrrscontours EH"at 12 per want,cent, ft6 per eentcent and 1!}10 per :2tcent [$5(85 rendingetreadings) .[-'nrtherFurther 1'Inorth,Dt'Ii‘t. in the sub-areaetth-ttree northttt'Jt'ti‘t endand etieteast efof SerigttieSangalo l[the(the heuntiet'gboundary tit"of the Hi1sub.. area ieis Sheenshown by a etettetidotted line enon Fig. '31:].3), the degree ofef feldingfolding ireis less extreme.extreme, moretitet'e gentle. neen atrttetttte gentle open structure being fertned.formed. Lineationslineetinns 51.1suggest|.\_.Igeet the fetdfold et-teeaxes trentttrend moremere . C11136 1’.I’-?I-1'-"1‘1-"--FL-S.E-W.N.W.-E.S.E. 111111and [1111111112plunge 111at 11111111111111shallower 1111g111111angles, 1'1111'1111-1variable 111111111about 1113'"49° 11-111.(Fig. .‘I'I.I-5). '1'11-1:The 11.111111:-rocks in111 1111:the ,extreme1111111111.: 111111111south of111' 1'11:the 1111111area 11:11-11have 1111:1111been 11111111111111disturbed by1131 the1.111.: K111-I1111111111Kavirondo 1.11111Gulf 1111rift 111111-1111gfaulting 111111and 111111111111111111infol'mation 111is 111.11I111111111111111.inconsistant, 11111but 119.1111again sugges:suggest 111111111111shallow 1111111:folds 111111with 11:11:1-axes 1112111111'1gtrending ‘11.-"-:'“I~1.‘1‘i11”'--E-51W.N.W.-E.S.E.1- 12'1”"”FI11.1.11.II-I11(2) FAULTING The11:1:111'111”-”1:11'JKabsabet-Plateau1-13-11111111 1111:11-area is:.I-”. 111111:structurally11111111.1 111‘:an upstanding1111.11 -.-_n1_11'1_1.1- 1111112111'111-111111-111block, bounded to .-_-_-[.1[.east, 11111111south 111111and 11.1.1.1west by1:1I_I.-I major1111-1’11-1 11111111.faults. __'|-.-. “—3- 1-. .... M 1' .' .. . ._ __ I. ' _ - The1...I. nElgeyo1.. I...... I_._.scarp fault1.11111 runs11-.11- .1111—[.1.;1.-11:1I1sub-parallel to111 the111: 1111-1131:"-eastern 111111111111.margin, 11111but 1.1111111111111211.-considerably1' further1-1-11..I: 11:11:11east 1:I-1'11:-than 11111the .1:-:1area 1...:[3g-I1-1:11.mapped. III-.11No indication11111111111111] of.11 hLI,1_I1-1:.;:..;I11-;1.'I11'11_usubsidiary' fauLting of1:I1. 1:1this:1: LIL-.111trend II - ' L ' 1:I - 1- l — 1--.- I--1-.I- 11111. :I-II. a-r - - 1 — I 1 ' 1 L- ‘ I '- 1.1 111 _11.-L 1.--.:1.1 11-11111-1141111.1. 1:111:- [1111g111-v-1I11-I11 :1: 1.11 was observed in the area, where ground-level rises progressively.- to the 111111..eas,t, terminating.III‘I111:I:111-:L-:l— in the low phonolite hills of Kaptagat, and the higher ground composed of the upper- ;-.-.1most volcanic-. rocks of Tinderet further south. The widespread,- uniform, gently dipping ... .II 1" _I I _ -. F _ -_ 1 .111111111nature II:of 1111:the plateau[1:11-.1-1..11:[:11..I-11I1phonolites11:- -L-1Ig1.II..Isuggests :1a 1:I-.I-1I-I‘1:fissure 11111111.:source 1:I:1111rather 1.'1::I:than .1a 1'11I:”1I::11central 1:11:11:cone .. . 1' -. ... J _I' .. —-.. .— C _.|.. .- ' :. -...'.-1:.1. 1. -- "'I .: u". -.. I... 1- ,_ r- .. tT-I r-u-' l-I-' .—I- II ..1 II-.- I": ..- .—.- .__. .—+ II. I. and the general1 north-south trend. --1of 1.11111--contoursII- 111]"Ion 1thev1" I-1‘1-11lava 1111:1111-1:surface 11-1111-11111.indicates 1'11:tha,t 11.11.11such 11a . fissure would probably— run on the Elgeyo escarpment fault-trend. The major fracture to the west is known as the Nandi fault. It runs N.N.W.- S.S.E. and has been traced from its emergence beneath the volcanic rocks of Mt. Elgon (Gibson, 1954)"1"'I':-'1 LIL}to 21-11its Lildisappearancefilifj'gfidi'11-‘11 'IL‘ into the South Nandi Forest (Huddleston, 1954), ”-11:11and :1_I_I”Iagain:1 fromIT-III‘TI- its11-” 11131-111111;crossing' of1‘1.I the1 1 Nyando- scarp to its. disappearance11-”'11:”: beneath.-'..JI-....'L'I. :1]:the 1.111111...: --1-._ 101H 11.11 111.1 11111-1.-' - 11.1.11:|..' 19111-1111.!111111-'1-1111' "1IJTI'...‘ 1111.111;'1'.. 1-"1:'"l-.--111__1. {-1131"I.” .-—...1:11--I_ -.1f.' .-1.-. alluvium. of the rift valley plain (Shack1eton, 1950; Binge, 1962). Over most of this -1. I "I 1111-1111112:distance 1:..1-1::':;south 11.”of Broderick1111111113111 Falls1.11111;- 11a pronounced[11” 1:I-11111111111 I1I.-II-”.—1:-1-.:5-111;:111111}:west-facing scarp resulting1111111111112 1'11I111from recent1'1::.II.I::: 11:_1-1.[LI.”rejuvenationI11:1 1:11: 111of 112-1.”-the 1111111fault indicatesi1-L1=11:1”1111I:”1 the1111: 111:111—11112-fault-line, LIE-1.but this11111”- 1111111111:feature 111111dies 111.11out 121111111111111112-southwards 1.11so that111111 1111111111111the point 1:11of 1:1:113”entry 111”of 11:1I1111111the fauH into11:11: 11:1:[111111111111131-1the present area 1.1;is in=11 11111111:some 111111-1113.doubt. "L1. 1! '- ._ “.-”--1 . '-.---I1 Ir1-1 - :I . :.-I - 1' . - :- - . . .11-..1-..-..1..-1.1Shackle,ton.- .-i.1I '1... 1.(1951,I.__'I..- 1. pI. 'XXVII)11-7111. .1.-. indicated.1111111111111,1. . 1111-:the-1. 1111.111southII- 11:11.end 11.-.-.of the1111:. Nandi11-1-1111.-- fault--1.11.11 111111.111.as cutting'L' --— -1. . 1 J . :I .I' J _l' _.l _" . _- : 'I1. -. _J —. _II 1 —.'I I -I ' - '.- -- .. -" . -+ -.-'. _. __.I I.- _.H L—' ..- 1 .- . .— l".- '11" ,- __i -1.J . ""..I -. _J . ..L- .-.1 .—.- I—J ._ I": .... '"I '1.» .-. 'I. I . I“ . ._I .... ..- I'1'".I |' .—. J? r the Nyando escarpment,._ and confining Nyanzian meta-volcanic rocks111:1..- 111to the.11: west,.1:-I... with ' .- ...--... r'...... _.- '- .- l—1. . “I Basement111111-311.1.-1-11 .II.-..~.-I1.I-1.-System 11-11-1110.gneisses .1...on 11.1:the east.11.1.1.1 I More detailed mapping has shown that several ..1.' 'r-I 1. 1.-= . - 1 .-._. 1. ....- .. _. 1_- ._ - .1 .1..- faultsin,1”-111.11 1..ofI.' N.N.W.-S.S.E.._"‘. -- ‘II -"‘-'---.'"'1--'*1=.E - trend1.1:.111L-1'I1I-1I.I1... cross '1-11:the 1:I-1.1.:scarp -I.‘.'1'-Iand-1. the[11:31 country21111-- [.1: north[111F111 of1.11 it.it, [1111;and that1:111: Nyanzian1:I-1.111.-.' 1 -1..1:. rocks111.....-.1 11.. .111-1are.1 -:1.-.[-:I..1-.1:I11.exposed,1 111.111.1111apparently. - 1..--.as minorI....1111111 fault-blocks,11111:' .111111-1 marginal.11.11g.-1-1'... to.11 the11.1-I. 1-.-1granite...... _.'...1..-- . -. . . . .E- ..." -._.:_ . ----'"-'.-. . - _. .. _._- _ rIII I1. ---_ _ -_I__-_I -11111-91'.and at .-.a number:11'1I.1I..1I_"{1.of placesi -.I.. 71111 within11.1111. 111-3the 311113-I-F-1L‘11gneisses 1311-.Least 1.11of the111.: 11111.71main fault.J-.l.|1. These11:51:57.“ blocks11111-13115 1111‘are considered comparable- .-.—..-..1[1-11-=-1.:. ...r.'. _. ‘I.....II.with-. ..Ir- '1 the1I._I.....-_1.1=-..r11-I-1.. blocks3-1 .'I-.. -.|'. . of1I... | " Nyanzian' 3.1.1.11111-1._. . . __ _I.. . . on-._ -._ the+1...... 1..11:-_.I .. top.: -. 1.1.111;of_.- J.‘_ the' -._ . '."II-..111.I--=.NandiF. . -i.. fault4....-1-.11.111-.I__ . ' scarp._.._..._ . . _ . . - _ ..._— I - - 1- . . in'1..-. the' 1L1-. - Kakamega11:...111..J.—I . . I_::I"I - 5"r- _.-area.:--.. -(Huddleston,F111...-1.I..-._3'I:-..1..1'!I.ewe-”.1”: .--.-i. 1954).:-'.-—..'.:Ii.."i.[I MappingLL'II-L. . 11'- Fir-L'”'.:L‘I1 II-.--.. is13;. L1|!_!.-_rj_l1_.r_1._._"LI_complicated.II.II- ”:31. .'. 1I --I ”L"by- [Ithe.- ||._. presenceELISE-E: '. - "|1.I_.I_I of5' ro.of-pendants1'111=-":|'-""'-’".I-u. -L11- 1'11of 111-133-111sheared Nyanzian”-11.111111 lavas11L"-1-1:I- in1.1". the1.... intrusive11:...1111'11- granite,1::- and by the diffi- cultyof1'11.“- 1'1'11 IL".“I||F”"1‘distinguishing.1I-1:1.- betweenllI...'=-'I‘I"1 '31" -1_11271511153513]granitized Basement12111.1"131‘11'i'5L System335111113111 13111.:gneisses and foliated con- ..- .. 1' .1. ..I . . 1. 1L1 . '1 '- 1 .. 1:. .1 '-.... —. .. . taminated.111111111111311 [gm-1...:granite where=‘--1_" 1'3. they.1I-1:I. areI[I.-‘I faulted1.111...‘:.1 against.1:-{11111111 one1.1111" 111.1111:1another. -"‘..-I-As 1a result1131111 . -'.11-of the1111' .1.presentII- . mapping1:11.! --._ I..1-I1_;-11..I1-I.I-the granite is considered1.1.1-1-11-111-11to extend1111.111. well.11:- to.11 11-:the -I1-.1-.I1-111east of the Nandi71-1-1111...»-fault. A1".. major.1..1_;=.I:an. -. — fault-zone11- . -.1+ -. I111-_ runs-. -.--.-- along_11111- . :; the1-1I western.-I II-IIIII_ - half11..-.. . of11.-- the11::- _ 1.1.11.1----southern-_ . -. .11.-_ boundary1117111.;11_-.1.-.. ... _ .11of.- the1.1-;! -. . .1 -_ .1... 1: 1 .I' .1. :1 ...... I- I.-'. - -.-_.-; "1131-1area and.1 '1‘".-: is11.1 the'1--I-‘ continuationI...-'1‘I.'l.-1"I.1.11I-L-DI'1 CI.of the1.1-: Nyando"11:1 11111-111 fault,1:1-1-1. i.e.,1.13.. the:--”--.‘I northern1111- :.'!-_‘"."1 fault1.1-.‘. of1.1: the11-13 '\I'.-"I_..'Kavirondo111-1111111111. -. I. Gulf(_11111.". _- ' rift111-.LI'I. valley.I..:-!1.-I-...'. For11-.' 1-— some_..-1.--1.LI1--. fifteen!I-I.-11.:11"'-"-. . miles_...'s11!-1.I-..- west..11:1....l of-._1.I._ " the1.11:1-1. present3-1-1111“.,,,,, I.. ...-11..area__ _ __ the..I-g-r fault:1-I . ' formsI1I..-I:I.Il.--..-|—--II1I a1..-_. notable.II1].1..'J._r1. 1-IL-1 scarpIII-r--.1I'I'I-II bounding.1I--Il-I_1...51111'_ I JI1III-1'F the'II-II. 1 rift1-.I-. .1" valley.. -_..|.__1-.II']1| Within'L-1-'-"".:-'.rIII..:.- the....-1:I-”I present.I—.I1—I--I--.I_I..--_":-_-!L .1-1.._1_..--.|._.--.I_I.._.._.-.:-.--..area, however,1"‘111'II1."-3‘I-"' the'I'I.II..;___1_ fault-1111.11- 1 branches111... :.-..-1:...: and-.1.1.11.1: the11..-..-:1 fault-zone1I.1.11.11.11.11.1 -—-. 1 swings:-..--1.-1I:I..I- more.-.1II:11 E.N.E.-W.S.W.1..III-1' .-1' Ami-1.111”-. and111111= becoming:1.-I.1. . I-1:. -I: less1.1I-.1. con-.1 - 10.-.: I. .1 -. . -. .- 1 spicuousEPlI-L‘uI-J. 11- finally.". .11: becomingJESLHflf-IE’. smothered1. L" "1 1"| -- by1.11111.-the uppermostl-DF-F' 11"1 flows- I- 11-. .on' . I". the~'.L1 '1 eastern1.“ 'I1'-.1 " flank'I'.‘1'111I'I. of1-1.- --I-.i.--..J ".1 11-: 11-11 1 -".--.--I-I-_'I- ."‘- '1! _.1-5: -I_:.I-I ..-.-_..I_-I_11.-. --.---- .-:--.I-'.- - _-.---_ '_"l_"L"-'"- I- .. -. ._-|.L-'1'] :II '!_'.--.__ 1,1,.IL_!I....'._!_"fir" I--.-'.-.--..'FLL . .1. l."._- |_.-I-.1'.._I.!.-. 'i. ..l'..| I. 1. L111. I...I_L..11. -I'|._."I... '1..-I. .1:-1113:"..- . 111,1 _1__ .1|._._ the Tinderet volcano. .In the extreme. south-east. an east-west drainage pattern is main- ._..___._r .--. ._.r"I l.“ 1 ._I.--1. . .._ 'I._ .. _.-._.....| 'I. I_'!_-...--1. .. Ii..|.-.Ii._- ..-- .. I tained {Fig. 1) suggesting"‘I:|.!..£. controlI.- 1.1..1LI byI.___I L‘EL-IL11‘C‘1—111-1-ulsubsequent movementI.--.-.-'"'-'—---'~.-.'.1 5.1.1on theL. Nyando fault-zone. The111.: faulting1313-111111111: post-dated[_1-‘111-111111111 the11111 deposition11111111111111: of111 the11111 Miocene11111-3111: sediments111-111111-“1:I: 1.1-1:as is.”.-_ 1111111'11shown by'11:. the1.111131112111111occurrence;11131: of1111'" these11111113 beds1:11.111 at1.11. heights11 '13:;1111”. differing111111311111”: by1.1- 1,0001111111} feet11:21 near1111111 the111;: SonghorEL1I-.:I_.I111”11I road,11:111.] 1111111and 111]alsoI-:I1’1 1’1..-:I”-.1-11I1-111”.:11post-dated 11:1:the 11111111111}:majority 111'of the11::1-1'Tinderet111111111 pyroclastic[11-11111- 1111111.: rocks,1111.111111-”.- while1:11:11:I[:11:I1:1:111111:I”preceding 1111‘.the -. "1 LL: :I-L' _.- I.- 7'... ..1 .-I"' L-' .I-I1 -I-.__] 121-. .—l ”-..-"a“ .-II .IIII-I' .II It'll“l ' I..|.-..I-._- 1. "'3 1. final1.1111 phase11....” of1:IF TinderetTII11111I1 vo'lcanic”1111111111111 activity.1113111111”. Binge131i 3:: (1962,111-111?- p.[1 47)"'I-..-.-I has postulated that it pre- '3; dated111111111 1111”:the Nandi5111-1311141.fault, 1111:111II11though 1'111no 111-1111111111:evidence 1:11'1131111111'1:of relative aguf-Iages 1.1115.was 1:11:11seen 111in 1111-:this 11111-1.area. 11::The ~ {Luann-am I :1 H.1— 3721.1 mun-trim: 111111111-1'11111'111'»:south-facing 11agglomerateLL1L111'1LF'111'L 1.1111111scarp 111'of the111.: .11-11111111Mtetei vaHey1-".:11L1-' region11:1111111 is1-1. a11. receded11:11:11111-1 11.1—11.1and I'LL-11:11much eroded111111111111 . fault-111mfault~line scarp,11:11:11 111111and 1.1111:the basanite1111111111111: lavas[111.-'11:. LnI.L'F1r1"-'entering 1111:the '111'111'11area 1'1'1111'1from 1111:the 11111111south 1111111and dipping 11111'1-towards'-1'L1.1.' the1111: 1.111111:foot 1111'of 1:111:the scarp11:11rp at111 about'11-11111.11 10°11'-'11'111'L-are post-faulting1111111-11111111111111 L111'L11.1111.extrusives. Both11111-111111:the Mtetei1‘1-11:11- 11-1'1111and 111p1111.1:1'1111'1111:1'1-Kipkurere va'lleys, 11.-1111211which 1"1111111-1foHow 11ppr1'111'111approximately111111:11' E.N.E.-W.S.W.1':-11.1.11 :1'-111111.11" 1111-1121-1-lines, 1'1111run 1:1'1r111'111'1'contrary 11:1to 1111:the 11.-1111:1111:anticipated11:11 11.1'111111'1L1'11'drainage 111111e1pattern 1111on 1111:the 11-111L111111'volcanic pile[1111: 1111.1-and 111':are interpreted1111111 '11 111111 1'11:as 11111111111111.1-channels L1'1'11'1'1LLIeroded _111'1:1'1:1'1::'1111111';.'preferentiaNy 11111111ailong fault-zones1111111.-1'.11111:.11 in111 111-:'1-'11'..':1111"1'.the volcanic rocks.11'.-11.1.1.- FaultJbrecciated-111111-1:1.1'1:1:1:1111LL1 volcanic1111111111111: 111111L1'1'111material 1.1'1is 1'111'1111'rarely visible11111111: 11111-1111owing 111to :11:the 1111111111111.copiaus 1:11:11cover'.L"1 111'of {1:111:11derived 1111111111111:-boulders, 1111111111!particularly'11111' 1'1-r11111from 1111-:the 1:111:11'.-'easily 1'11-111111111.111111111-'-1:L-.111L11'111:1'1eroded, poorly-cemented 11119-111111111'1'1agglomerates1:.: 111'of the11111 .1.-11111111111111.1111south-facing scarp.11.121111:- The11111 111111.11sma:ll [111-'11lava 1111111.:flows af 'basic1.1111111. 1:11r111111111111r1compasition 1.1in 1111:the 1'1-111111111Mtetei 1'11-11-11ValNey11.-'1:are 1111111111111probably 1'11-111.11:some 11111-111:of the 1111-11-11.most recent1':-1:11:111 L111rL1111-1'.extrusions 111'af 1:111:-the 11rL11.area, 111111"and they111-1:11 1.1-:11:were 1111:1'11'111'1.derived 111-11'.:from vents,11111111. ."1'11..11'111~-significantly 11111111111:aligned1.1 1:111'an 11-a 1'1'1'11-11'1'11'1'111111-11'11'111raughily east-west 1111.11111-trend. 111111‘.HrIls 1111'of '11'11..1'~:.1:1'11L:'1‘1Basement System111111111111? rocks1111:1111 '.1-1:at 1111::the foot1111.11 111'of 1111::the Nyando1"11'1'11111'1111 1.111.scarp1.111 11::lie 111to 1.1.11:the 111111111north 111'of 1111:the 1.:-1111111-LL1assumed 1111111line 111'of 11111:the 111major1111: 1'11111111..L-'11'11:111'1faults, and in 1'11-11the 1.1111111:scarp 1111::face 1111121gneisses1.11:1. 1111'.can 111:1be 111:1:11seen 1111.1underlying'11:"11:11:: 11:1'131'1'111'1'111111111111severall hundred feet1:1-1111'af 11L-11111'11111'11.".11.Lagglomerate 111at 11.a 111.-111111height 1:11"of 7,000'.1-11.111.- 11:111-feet. Th11111'.This is 1111-:-the 111112111height 111to' 11'-1111111which 1'1:the 11.111hill 11111::1'11-.'111111'111:1.11.111-1111111..111'11111:.tops further west appraximate, 11':the.1: 11:1'1:1level L11"of 1111111L111L11111':Shackileton's 1'1-'1-(1951,'1" p. 1'1-1".11'1'11111111”379) "high" peneplain.1'11-1111111 '111L1'1'1111111'11-1111The hills south 1.111111:of the 11111111111:111L1rL-1'111'L.1:1'11111111-1111'111'1scarp are, therefore, considered 11:11.1:1111'11denuded 1111'of 1.11their1111' 11agglomerate'1'1'11111'1'L111'11L 1111:1'.cover, but11111 11111not 1.1:1'1111seriously111-1.:.- 1' 1:11displaced111.-1111:1111 by111' 1'11-1111.12faulting1'1-'1' relative1"'1'11111-'L1 11'-11.111111to the 1'111'1'1'11rocks 11.111111111111111.to the north. T11:The 1'11-11111111111Nyanzian 111111:r11poutcrap 1.11at Koyo111111111 11111hiB 11'was:11. mapped11111.;1111111 11.1:as 11a 111-"1.1.111down-faulted1"-'fil1l111.:'1'11 block111111.111 111111.with 11111-111111:tectonic 11111111111r1L11~baundaries 1:1-111111.111against Basement{111-11111112111 S1-'1.11:1111:1.1'1.L11.1.11System gneiss, 11111L1and 1'111-11111Lgranite 111of post-Nyanzian11'-11.1111.--'."1.1-'111'1.1'.'- 1111 agL'.age. 11111111.:More 1111111.than 600[1'11-1'1 feet!LL'1.111'of Nyanzian”1.1".11'111111-11 metavalcanic'111-11111111111111... rocks1'11: 1.:-11' 1111:are 111.-111111111111displayed between1'1-L'.11-11:L1'11 the1'11-L" tap11'.-'11 of111' KoyoK1111} and1111111 111L:the bottom1111111111111 111of the1'11-1': 1--'1111L'1.'vaHey 11':to the111': north-east,11.1'_11'111-1:11.1~:'1. and111111 1111.1":more 1:111'1'1than 1,0001 .11-1.11.1 feet1.1:L'1..11'.in the11'.-L 111-1.11:1:1111'1dissected 1111111111scarp 11111:face 111to 1111'the 1111'south.1111' . Faults1"-11111. 11511111111111:respons~bte 111'."for 1.this magnitude:1'1111'1111.11111- 111'of 11111111throw 1'11-11.1111cannat 111:be 11:11:11referred1111 11:1to 11-a '.1'31'111-11'11"Tertiary 11511-age if.11'.' 111.-1'.:the 1:1-1111:112111111'1111carrespondenceL1: 1.1:"of peak111.-1'1.1':1-'1:.-1.1levels 1111'of 111111.11Kayo 1'2'121-1Lr1:1'.1"1'11'1(Nyanzian meta-valcanics),111:111—1-111-"11111111111;1'11:the hiHs111111. to111 the1111' west11'-1.1.11 111111211(granite),.111111 111'and.111 11'-1.11.1:those to111 11'-.11.:111'1the east 11.-'111and north-east1111111'1-L1'1111' (Basement(1111:.L'111L11t System1"1'1'1’1'1113.1'1"I§.'-T'11:1F.'1111'1'1gneisses) 111111.11owes its1111 origin1111:1111 to11'-1 peneplanation1:111:11.1:;1111'111-11111111". in111. pre-Cretaceous[1111-11 ' rL111:1:11-'--11.. times.1.1-1111':- 'l'hL‘1f111'11'1111'1'11111The Nandi fault passes11:11:11 1111111131through these1111:1111'11111.hHls 11111111111without 11.apparently'111111'Lr1'111' 1111.1111r'11111_L-_1disturbing 1.111:the peneplain111:1:1111111111 level.11:11:1- Accepting.-—‘11LLL11:111.11L1 111111:that the1111: hiNs11111.1: on11111111:the tap1111111 of1'_11"-.11.Lthe Nyando1111111111111 1.111111'1scarp representerL' 1:11'11 remnants.'L-1"..1".111.1.~'. 111'of a'1'. pre-CretaceausprL-E'f'rL-1-111:L1..11111 [1:111:111111peneplain.'1 both1111111 11'11:the Koyo111-.1111: 11111hi ‘1"'I—1‘11H'.‘"'1'I'IR1'-"11I-VI-MINERAL DEPOSITS1'11-1711111111111 1111121No 11:11:new 11111111311111mineral 12111111111111:deposits 11‘1"11:I'L".were located1111;111:121 1111111111during 1111':the 11111".L'1-'.survey. 1. (11111111Gold 11111The Nyanzian111-11111111111 1'1-11:11:11rocks 1:11Cof 1111:the 1111::area are:11: h1g1111'highly fractured11111111111111 1111111and 1111:111'L11.sheared, 11:11.1and injected111_1L1:1L'11 111-by mineralized111111Lr111111L11 111-111111:quartz 1'11-111:1.veins. T1111They 1.11:are part1111-11 111'of the111111 1111111:same volcanic1111L111'11L 1111111:-suite, 1111111and occupy11111111 p11 11a 1.111111111-similar position111111111111 1111111.1:1:11.1adjacent 1111to the1111: major1111111111: granite11111-1111L- '11-1'as 1111do 1111:the Nyanzian11111111111111 1111:1111rocks 11:11.1near Kibigori11111111111111 11.1at 111.1-the faot1'111'11 1'11'1111:of the 11:11111scarp, 111111-1111where 1111:the injecting111c111111 111111111quartz veins1'L11'11. carry1.111111 gold111.1111 in1'11 12.111111111111111:economic 111111111'quantity.111'. The1.1.: presentprLLLnl 111-111'survey111' has111111. L1:1:1'111L111extended 1111:the 11:111.:1'1'1outcrop.11 111'af this11111. rock1'1-11:11 type'11-'111: 1:1-11111111.:1'111111'11'11considerably to' 111.1:the .1111.narth,'1'-11. but111-11 111111111111-11-111111111'1111rapid investigation indicated1111111L'1'11'111'11 1111-11that 1:.-111111111111:extensive goldL1'11d 11'11mineraIizationr1L1'1I1.1'.1'111"11 is111-.11111111L11'.not likely. '11-'11:The graniteg111'11'1111: 111in 11:11.:the KoyoK1111} .11-11:11area is11'. cut11111 by111' TElEI'DUHnumerous 1111:1111small quartz111-11111111 11.11111.-veins, .1111111L'.same L11of which11'1111111 Larrycarry gnid,gold, and111111 it1:. was'.1-11.11111in 111111this regian1':-1:111:11: 111:1that Gari£11111 111111111111Hansen Blijah[3.1111111 1111111L11carried 11111out 1'111L1'1LL111opencast mining;mining 1111on 11a 11rr11111sma'll 11:1111:scale 1111111from 11141.11949 11.1to 1115:1-1953 111.as indicated1111:11L111L11 111in 1111:the 1'1-1111111111:following 1.11111L.taMe. .-J 38I1.1.11 E1. 51:1-111..1..=:1-'SUMMARY L11:OF HISTORY111.11.101.11 :11-'OF L21..-1.1:1GARI HANSEN1111:1113: ELL-1.1.H'11ELIJAH'S L"L.1.1.'.LsCLAIMS UL'L:are {11L'11L1Gold 2119.131"No. of Year.:11' '.rL::111:L11treated recoveredrammed 1:11:1111:claims 11::lheld {:.'-1111.111(tons) 1:11-11(ozs.) 11.11—11.111949 .. . . 1]11 12'3212-22 11G40 11.1.1.1.)1950 . . . 121':126 47'47.272-? 1‘1242 19:111951 . . . 211'-29 4-514.51 22 1952191112 . . . 1'* :"1-5'11-116,56 2E120 1953111-1:13. . . . 31':30 111-2:116'75 11114 1115-21-1954 . . . — L16 11115:?1955 . . . . -— L'16 195611151.1. . . . . — — L'.-6 "'.".'.'.'I*No 1133.13.11:figures.'=.'-..'.'1|:'.i".I-.'..available. At911- the111-'.': time111113 1‘:-'11of theL111: present1:11'L:11'.L.'111'. survey:.'-1.1".11311' no11:1 work1.11. .111: was1.1.111. in:11 progress1111711216111. at11: L'..'-11.1.11Gari Hansen111-1:111:11 Blijah's1'1:1:1:1' 11'. gold-mine1:1111'1'1111111 at1'11 Koyo11111111 and1111111 most1111-11-11 of11 the1111: workings1111T11.1L111:1. had11111-1 been11:31:11 infil1'led11111111L1L1 and311:1 were111L111: thoroughly{11:11:11ug'11111' overgrown.L:1'{:..L.11.1.-'11.11':1.L:111'11"1L'The mine was111-".11“. visited11111111111 in111 .11111..-_.'July, 1950,1:111 1_'_1 however,1.....-1...r by11.11;.E. P.1.1. -E111111.1-.L1r'-Saggerson, :1a {1:11-1:11-Govern- ment1'11 ’1'-111- geollogist,1'11'1""1'-1 who11111.1 describedL1L'1-21:1'i-1:1:L-1 the111:: form11.71.1111 of111' mining1'.-111.111.1111; as1111-121111111-‘111'1entirely 111711.111open-castL::1'-'.L work1'.-1.1.11: with'1'-1:11 1.1.1111:some trenches113:":1:111:11 up1.11.1 to:.'-'1 202-11 feet11:31. L1L:L.'p.deep. At111.: that111:1: time11:11.: there1111-1111 were1.."- L':'E' five111-'..: mainn'1'.11:1 workings1.1'L'1r111n11: _.-._1.grouped111.1111“..- together1.1.1.:6111:- about7111-31111. :1a mile111111“:- south-east.-'.L'.-L:".11-L:.'-L.'.'.L L11"of KoyoK1111..- beacon,11:11:1'1'1za1:a'll entirelyL::11:11'::1'.1' 1111111111within quartz-richL111=-Lr'Lz-1'11:11 granite.1:1'311111: T1111:The gold-bearingg11111'1111111111131 1111111111111quartz is111 11a blue11111111- variety111111113- occurring111111""'".L ini-.". lenses11:11:11.1..- which-.-.-'1'11-.'.'.1'1 rapid prospecting:11":1.1;:1L--::1111L1. showed1.11:1:1'31'1 1.1111did m1!not ::::-:L:L:11:1exceed F11160 feet11:.-"'1 long,1.11113. 2 11EE'I'1111L'1E'21121L1211-1111131211L'131111E121111feet wide and 20 feet to 30 feet in depth.:151311'11. THC-“1:1.Traces L111of §E£11L1gold 11.111121also Liz-.'.:L:L11'occur in111 :-]L.1:1.'L;-.'.quartz 1.-'.1'.i-'1.-.veins 111in '11-'...the Basement11L11'.1;:1.111:.":'1L HEEL-1:11".System gneisses111-1.11.1.1. L11:to L11:-the 1:11-11.east. T11:The 1111.111:1':=.11".-:'.:'111'.'111minera!lization :.'-1'of 111::the 1.1.1.1.:11'121:quartz veins1.1.1111.- L111on L111:the 1:111:11top of 111-L:the :.L:.111'pscarp 111.111.111.111north of Ext-1.11.1Koyo 1111::and '.L'iL1'.within1'1 111-1151.5.HL1'111'1the South Nandi111-2:111:11 Forest17:11:11": is1.1. 11pp:1.1'1::.'1111=apparently 1111:1111}:mainly pyrite12111-1.“ "11.: 1111::and 1-_1.':'11L11gold 11111:has been111-"1:11 1'r_'_1:1-.'-.1'LL':L11reported from115L111": streams1.1.'L1'.-'11T1 north-west11:111'1111911'12111-211'1of Kaptumo.H:L:111:1"11:1. OfC11" the1111': 22.22 samples1.:11'1'11211-.:.1.' submitted1.1111111111L1L'1 for11:11' 31111511.“assay 31-11all but1.1111 1.11:2:three 1.1.11.1:gave negligible111-11.111.1T1L11L1gold '.'LL1L1L1L.values, 1'1:11'.1L-:none from1':-'.111'1 the111-.- northern1'1L'.11'111L:1'.11 L:.'-.'.LL:'.1'1:-.1L'.-11extension 1.1;:of the111-F: Nyanzian1'11'1-11121113 11:11.:r11poutcrop yielding'..-“1::1L11'L11'1. more111-11.1: than111111.:1 traceLI'ELLJL' amounts311101111111. L111of gold5:01:11 while1.1."I'111L: only£11111.“ low1:11: values'."11_]-.113:. were111-e11: obtained1.111111111111113 11111111from 11:11:11.1..11'1'.stringers 1:1in theL111: graniir:granite :.L1L1and gneiss-.-'rIL:i.1.'.1.'. 1.1.11.1:11.south :LLLLiand 11.11111-L1L'11LLnorth-east .':-'1of Koyo.111111.10. Many111.:1111. 1.1::1:Lr".-1-.streams were'.1. 1:11: panned11:.11'.:1L:L1 without1'.-“1111:". LE-1. 11'Ei.-L.‘-f."..1-'.traces of1'.":11'1 gold1'__1L'.11L1 11:2!1'1-2being found.1L:-L.1d. 2. ScheeliteSLTLL'fliiL- In111 1952111.12 :1a 111111111sma:m Lit-11:11.11deposit L11"of 11.:11'L:-.11:'scheelite 11:11.was 11:12:11.1:111located in1'11 :.'-:1..-one of 11'1111'1'Gari 1H::11.-'.'L:1'1Hansen Blijah's1.1.11.11111'1' T 1:11:111111.claims, 1.1.1111:eas.t :11"oLfKoyo.11'. :11."L'1. L.1.. D.111.11.1711.’r:1'1:.'.-1Sanders, a 1'.:L'11L-'L:1'."11'1"1-.:1".1Government g>eo1ogist,_L_1.1-':'.-.'11-'.'.-1._'11.1:1. 11:11.“examined11'.'1i1'1.'-:-.'.1 1.11::Ithe minerailized1111'L1L11'211i.-'L:-:i :1111'11'1'1'.quartz 1.11.1111.vein, but..LLL found1:11.111 :1 the111:1 scheelite.-.L: 11:11:1111: 1.a11:.1_:11'.:.:1111.':jL1'111L1L1L111L11.:111L':sporadica;Uy developed, and L111of negligible.11-31.1111111111: L1LL'1111LiL'111.quantity. In11': '.1.a report1cp1111'1 onL111 11111::the 1112.11.26.111'1:1".".111L:-"1111'1::1'Li:'.1.11.scheelite mineralization, S:L.".L'1'::L:~'.Sanders HULL-1.1.1stated '11::LL:.':':-.1L1L1.1111111}that about 1,000 yards'_1.-':-1.r:1.-: 1-.L'1L.1111L-'1:.1.'1.south-east L111of Koyo111:1}.- beacon1.1L:LLL-'L.'1.1'-.L("Keiwa"'11-611.1111 1:11:11111'11'1]location) ELa LL'L'L'1L1'LEL1trenched '.1-.1-'.1.'i.".-'.1working .'.1.1'.1L.1.1.tL'iexposed three1111'::L: thin111111. .5. gold-bearing.:-L1i:'1-11.1:.:1'1.11_;-.1 L1.1..1:.1.1'L.'11quartz 1.":1'11111.1-111.11i1211"!.veins, which .'1-".1111occurJ 1.11in LjLLaL'L-L'ECELquart-rich biotite1'1:-.'.-L'.1-.': LL1'1.1'-L.11:1granite 9.11:1and i.1'-.'1'1:1.trend :-:[1.r1:'L.1.1:1-approxi- .1. mately111111.111: north-east1'1L'1I11'1:.:111LL to[11 11.1L111'1-11.L'1:.Lsouth-west 1.1.1with1.:1'. a:1 :111'1-'.1i"?1.1dip of 70° 1.1to 80°115.1: .1.L.1L:11'.--.:1L-'.'-..south-east. They111.11.“ .11L11.-'-..'::1.showed minor1211:1111' LLLLnHL'urrLL:transverse faultingL'.LLLELi1'._.-1" 1.1.11.which11:11 caused13111-1111." .1 12:11:11LLL:L:11'.L"."1':.'.'displacements :11of upL111 LL'1to 1 foot.iL'LL'LL. fiOnene of:11 these1111-1111: 11:11:11..veins 1111:111.L:L1showed 1':-2111:3111:scheelite 1'1111'1L:1'1111:-:ELLiL.'111mineralization but11 LIL 1.11:1the 11.911:work accomplished11.1131311111p 1.1.11.2: indicated"11'.11C:1'1‘L-"..L.1 111111.that the111:: 111LL1:11'.-11.11".-1.maximum width111::11'1 of:1'11 1.1'1L'the vein1':-"111 1.1.511:was 1.19 11'1::1'1.-.1".inches, 111111211511:thinning L1L1L'..111.1.-'11.r'1'...-'.downwards 1::to 1'16 inches11111211211121111'11and pinching out1:1: 1:1to :14 inches1111;111:1111at 1.11:1.-the 1'1-.'-.north-easterly111-'1:11.11: 11.1 extremity1.- .:.-311111111 1112'of the1.11:1. working.'.1-“L.11'1L.:31'.1:1.. ELLE-.5111 -1.".-.' 1111.1 Green-brown, L'.L'11'.':1':-:1:1}-'coarsely L:."L-'1_'.‘1:1'11i.."-.ecrystalline aggregates111:1.1'ge-1_-1_. .11-1:11“ of:.'1 scheelite.1..'.'1'.:-.L111 1.L_: :occurred.:L:1.L1'1'L'.'L.1 in13': scattered1:111:11-L111' pockets1.1GC1LEL1. in111 1111—:the quartz1:11-15:11? and'.'LnLL had111-1:1 'led1.:1 1:1to deepL1-1::1_11 pitting11111111.:11111on weathered1.1.'L.-:'11!1.L:r1.-L1 surfaces..11...1112:1311- Over1.11.15 a:1. strike11:111.: distance111.111.1111.:L: of111‘ about1:11.311: 1011.1.1 feet11cm there1111.111.- was1.1.-':'11:. a1'1. workable1'.-1111:3111: L'::'concentration1.1".L:L:.'1.11:111:11: LLLLL1and ::a channel-sample1:11.1L1'LL11-11-1-11111'11311e. was11.11.11 taken1:11:13] from11:11:11 ['1'-.11.this partpari ofL111 1.11::the reef.T't'L'f. Subsequent-..1111L'11.'L:L1LJL:1"11' assay111:1.1111' showed1111-L1LL'13L1 that111111 1.11::the sample1.11112113113- containedturns-11111126. 5.5.'1-.'1 per-1:.r 1.213.111cent ofL'Lf W03,111-"1T1. but111.11 Chéln11L-‘1-f-12121111-311channel-samples taken1111::11 1117-111from 11:151....11111113neighbouring parts{11:111. of:11' the1111.1 vein1.11.1111 in111. 11.111121.which there111L111: was111-"1:1. ilitt!le11111:: visible1111111111.: scheelite1'.'.:1'.L.'1'.—'.1111:'. proved.'11'L11'L::1 11:1to containLLLJLL’LLLin on'lyL11113.’ 1.1.1.1170.07 per{1:11 cent of111 W03111111-111. L111on assay.1511.11.12.11“. EtherOther 1::11gold-bearingflu11L11111'11'1LI '.'L:11'.1Lveins '.1-1111.211which 1'.:1'1h:>;j hL'L-.11'11.1-'L11'|~'-=':1been worked 1'11.“by E11_i'1'L1'1Elijah 11111-1and 1111:1111.“veins :11:cut 1111'by 11:11:21;-neigh- '.'"1L'IL11'111.1_:1111:111111.bouring streams 111-1:1:were1 L:.':111'r'1111L'.'d.=.1."examined for 11L':111:'L'-.11.'.:scheelite 111.in vain.1".-:11'1i."1.L:E'-.'1Hoat 1.11:.samples11:11:21“ 1:11:11from 1111111111'1LL-L.unworked'1 reefsr1:1:f.~' 11:11::were 2:111:11aJlsoinvestigatedE:1L-L:.~.Li:;:LLLL:d '.L'ELhL1-11’Lwithout :-.LLL.'L:L'1.'.1.'.success. """ 39.39 NoHI:- fLLLIIILLrfurther LLLLLLLLLLLLLILLL:occurrence LILof scheeliteLLLILL-LLLILLL: LIL'LLLLwas :ILE‘LEIIseen duringLLILLriLIL.L III-.-the present['L'LI'IE‘HLJI'II mapping,IIILLLLLLL'LILL. nL'ILnor hasILLIL anyLLLLLLL beenILILLLLLL LLLLLLLLLLLLIreported I'LLLILLfrom LILL:the areaLLLLLL byILLL prospectors.LLL'LILILILLLLLLL'LL. 3. LimestoneLimLLLLLLInL: Hi)No LLLLLLILLIIiLIL:crystaUine limestonesIiLLLLLLLILIILLLLL LILLLILoccur LLLILILILLLLamong LILLLthe gneissesLLLILLiLLLLLLLL LLIof IILL.the BasementIILLFLLIILLLHL SL-LLLLLLSystem iniLL IILL:the area,LIILLLLLL huthuI. LILLL'Ethere LLI‘L:are LLm'L'LIIsmall 'bandsI.L:LILLIL-L LILof impureiLIIpLIrLL. limestoneIiILILLLLILILIL: LLLILLLLILL.among theIILL. claysLILLL-LLL andLLILI LLLIILtuffs LIIof theIILLL- Mioceneh-IILILLLLI-LLL .LLLLLIIIIILLLILLLLsediments nearLLELLL LIIL:the :LILLI'ILLILLLI'Songhor roadLLLILLLI atLLI theIILLL fLLLLIfoot LLI'of LILLIthe NyandoT‘LL'ILLLLLLLILI. ‘L'LILSEEII'J'TI.scarp. ManyI'LLIL-LILLL ofLLI KILL:the 'l'inLiLTinderetfl'L‘I. I‘L'LJHFLtuffs LLIIIIZIand LnILIIagglomeratesflLL'LLIEL LLI'LL.are, inIII LLdLIiIiLILI.addition, ILELLI'IILLLhighly {.‘L'iiC-i-lTIJIITIIII-I.calcareous. 'I'ILLLThe LIL-TILLILLLIIL:Miocene limestonesIiL'rLLLLLLILLILLLLL ILLLIL'LLhave !been‘LILLLLLI LLL'LLLILLLLIworked ILLto LLa .LLIILLLLIIsmaill LLLLLLLIILextent in II-LLLthe past.LILLLLL. InILL LIL:the LLL'LLLLarea fLITIhL‘I'further L'LIJIIIILsouth LLLLL'IIsuch ,limestonesIiLIIL-LL'L‘LLLLILIIL L'LrL:are beingLining IL‘ILIIILIIburnt ILIIfor 1LIII-:.-ILLII.lime, but tIILLthe IlimitedliIILIIIL'ILI :LLIILLL‘LLextent L‘LIof LIIthe limestonesIIILILILLILLIILLLL LILin IIIL:the presentLLI'LLLLLILL LII'LLLLLarea LLLLLIand IILLLiLLtheir LLLLLiLLIL'LLL.variable CIIT'I'IDL_I'L"LIEIIL'ITIcomposition LLLLas inferrediIIfLLI'I'LLLI fLLILLLfrom III-ILIIILLLILL'LLLLLLL:appearance in handhand-specimen,LnLLLiLLLLLIL. LLLLIEILLLILLLIsuggest thatIILLLI LLLLLLLLapart fromIII-’1‘] LLLLLLLII-LLLLLILLL.smaH-scale burningIILLLLLLiLLLL fLILfor LLgI-L-agri- I:LIIL'LIculturalL'L-LI limeIiI‘LLL: .IIit ‘IL-LLLIIL‘Iwould bei"11.'..' LILLIIdifficult.L‘LII'LI I.LIto LLLLLLIILIiIexploit IILLLIIIthem :CLIILLJIILLeconornicailly.LL—LLILLL. A.iIL LLLLIIiLiirsimilar LI'ILLILILL-LLI“condlusion wasLLLLL I'LLLLL:reachedILL-LI L'L-LiIiIIwith regardLLLLLLLL'LI toILL .LLIILLLIIsma'H limestoneIi.LILLLLILLILL: LILL‘LLILLELdepositsLL LLLat Keben.ELL.ILL-I. HereHI.- I." limestone:LILILLLL.I LLIIL'L boulders,LLLILL-ILILLI'LL. :LLL..ILLsome possibllypLLLLI-LiIL-IIL LILLLLLLLLL'derived fromILLI:LI theIILL'. LLLLLLLagglomerates,ILLLLLIL .LLLILLL- LLLL:are LLLLLLLLL'ILLILIaJbundant IIIin III:the proximityI‘LLLLILLLLLLLLL LL'L'of theLILL: LLfILLLIg. UIILLEL HILL.i-LLL' spring. Other blocks L.LL:L'.".I.Loccur I.LILas bluffsL‘IILIIILL inELI theII1L'.'IL-:LI"Isteep LIL'LLL'IL.waills LILof -'.-La LIL—LLdry LLL'ILLL-va:LleyLrunningLLIIILILILL 11LI’I‘I'-north-JI. 'L'L'LLLLILLL'LL-Lwesterly LI'LLLLfrom ISILLLthe poolLLLIL'LI 'belowIILILLLI' IILLLthe :ILIII'IIILL'-spring, LLLLLand LILL-Ione LILLLLLI'LILLoutcrop LIL'of iIi'I’IEI-IILLII‘IL':limestone LILof .Ii:LLL'I:L—.-L1‘limited lateralILLLLL'LLLJ cr-LILL-LLL.extent LIE-LoccursI.LL‘LL in the”IE floorLLLILLLL LIL"of theIIILL. guUy._L_L_LLIILL_ "ITheI:L-LoriginLiLL LiL_IIL LI'L'of thisIILIL. IlimestoneIiLLILLLILILLL: isILL TI:Lin LILLLLIIL‘Ldoubt ILLLIbut, inI.LL LL.a LLLLLLLL'I;report LLL:on theLIIL LLLiIILLLLI'.minera'l LLILLI'ILL-spring LII;at Keben,'LLIL'LLIILLLLL. I’LLII'L'LPulfreyLLLL .L-LILLsuggestedLLLLLLLLL LI'LLLLthat L'Iit :LLL'LL-may I.L-LL.be ::'.a LLL'EIL're/lic LLI'of .‘LIiLLLLLLLLLL ILLILLL: ILLLILL L:L.IIILIILLLLLLLLII ILLLI'IiI LL Miocene !lake-beds comparaJble with I.ILthoseLILLL onLLLL IIILthe LLLLLIsouthernIII LIL ILLLLIILLLLL-L:boundary ofL‘Li: LILL-Lthe area.LLL-c-LLI..'_ 4.LI. Brick-claysIILILL-LILLLLLL .LL"....'. .— ‘ .— .._.. L. E..—...'-.' ...'. _.'_. _ '_. ._'. .._ .. ClayIL I:L} isLIL-L dugLIL.ILI' and..-J_ I LI bakedI'IEILI-LEI'LL as'L.'.:-L bricksLi'II'iLIiLII-L' atLII. ‘LIILLL'ILiII'LiseveraJl localities,LIJILLLLiILI-L‘H. bothLIL-[LIIL from-__ILL'.II'I.L depositsLiIfiLLL‘I.L~.’[1I onLII] gneissesLI.- I.1-LILIIL.LL and.LLLLI LLLLon phonoliteLLL'L.LIILLIIIIL: lava.ILL.- .DOneflfi LIIof theIILL- largestILLLLLLLLLI pitsILiILL isLL situated.LLiILILLIL-LI halfILL-LII LLa mile.LL;:'IL: IIL‘II'IILnorth :I'of CheptetII'ILLLILILLL'. mission.IIIILLLIL'LLL. 5. IILIiiLiiLLLL—LLLLLLILLLBuilding-stones I “-_1- . . . .- 1 --I. . -.. . - 'I- I II .- .-L. a -- I 1- 1- |. .- .-I.... L-_. 1' . I.- ---|I ‘- .|:.-.- TuffsilfLLILL- Ll[.LL.:and agglomerates-ILLIIIILII-I':|LLI.ILL‘..L L-..II.L."L-I~I.!:'ILL_'consisting ofLL.-| :LLIILIIIsmall rockLL‘.1L_iLL TILL-:LLIILJILLLLLfragments, suitable:LII-.-LLJ_L_"I.L.' forIL"'1 ".ILL-LLI'LLIIexploitationIL. -L.'.||'IL.-'L. .._.'.'I .: .+:.-1 - r:_-~-L. 1. 1... 1, . .. l' -_. ._ 'T '_ as building-stone, are of wide'-~I'L'L~.‘ distributionI:L.“LIL-IJILLI-LL..-I: throughout'L-II [LIL-LL“; LL‘I 1| theLIL-L: south-eastL-'"-'.LiI'__-‘L—-1.|.LLL of-._‘L.- the11|L. .LILHILL“area. TheL_._- f" ‘... .1;. _ L-L.... potential supply”LLLLILL' mightI‘I‘III‘I be.LL: classifiedLILLLLLLLLLLLL as..-.-L unlimited.I.LLLLLILLILLLL Many.LL..-;L-. smallILL L.I.i quarriesLL. .. -L.-...~L areL'L': apparentlyILLIJ: LII" workedLLLL'LLIILILLLLI periodically,LIPI'LLLLLEIJL'LIILL. mostlyI.‘ILILLIII in51: aLL. ratherL'LLTLIILLI' unsystematicLILLLLLLLLIL-I‘I'II‘EL‘ manner.:II'LL"LLILL' 6.{‘31. MineralizedfLIiLLLLL-LLIILLLLLI Waters“LL’L'LLILLLLL WaterILIL":'L‘.L'I' L.LL'.LL.LI'LL_'II'L._-.=.emerging fromL'L'L'LI'LL IL'LLLthe I-LLiL'L'LtIL-L.‘volcanic rocksL'LIL':|~:.~L LLf'of "I'iriLI'L:TinderetLLL carriesLLLLI'LILLLL aL highItfggLLproportionLIi‘III;'LL L.:_of Li;-~:.~LLIIdissolvedIL‘LE E-IL'LILI'LIL.salts, inLII L'LLLI'iILJLLILLI'particular L‘LLICILLIILcalcium IIILLLLL'ILLIILLLLL.bicarbonate. PebblesIILLiL-IL'IJL .5I'Lin LILIIttL'some LIL"of ‘LIL:the rLLILL'LLLLILstreams LILin the'.L'.-L' Northern"LLIILI;LL'I1L TIITLEEI'LTinderet ForestILLIHI areLIL: LLL.L‘L:LIcoated with'LLLitII re-precipitatedI'LL-L31'u-.:iLL§"L:LIL-L:LI :LLILHLIILLcalcium LLLI'E‘LLII'L:LLLL.carbonate, :.L!IL‘.and LLLLL’.springI:L '-LIL':L‘LL:L.~LLwaters, LLbothIii'I fromI'I'LLII'I IILLLthe L‘LIILIIsI'I'Ieastern L-I'LLIend LLL'of LI'LLLthe Mtetei.‘LILLLLLLL' I‘L'LliiifL'valley LLILLIand fromI'L'LII'LI Keben,I’I'LLLIJ._LL‘. fiveI'LL: and ILa halfILL." milesIZIIIIi‘L'LI LLLI-LL'LiL-LELLILIsouth-east LIIof Lessos.LL‘LL-ELI.‘:‘L'L_EI'1L'1I'L".have reputedI'LLLLLLILLLI IIILLLI'.medicalL'LL value.L:.LiL:L'-. The'I'ILL‘ KebenIILLLLLLLLI II-L.I'.L‘1'water I:LIL'I'LLL'Lcarries LLa ILELLI':high L.--.IIL.LLLIL.LI.concentrationLL. LLII LLof" carbonL:: L1 ILLILL LIdioxide.LII-L: .TIL:The Nandi'LLLLLL'i.': haveILLLI-LL certainly:.::“.:L"L'LI'_L' L-LIL‘LLL'LI-LLLL'LLLJconsidered theLELL: latterILL III‘I LLLLI_water beneficial::::L'IL-IILLi'.LI toI.L IIII.‘the healthII::I:L LIIof theirII'LL::I' cattleLiL. forI-..II’ manyL‘I'LL'LL'ILI- years,2LL‘L'LI':~. happilyI'LLIIIII:I}' contraveningL.'LLL‘-_'.;':LILLII:'LI;J LLIL‘LLLLstock _. _. L ...... 1. -. .. _ .. .- .. . .' ' .' : LIL. . .-.' I . LI-I. movementILIIIILII-I'E-I-IL 1L}:I_'Lregulations.LLJLLIIL‘LL inIn ILI.Lii._’order that-.ILI'. their[LI-Li. herdsI'IL’IILITL might:I:Ig.‘|[ "Ila-1Lvisit the.ILL‘. .‘LFJI'LI'IEspring periodically.I.‘IL_II.'L'_ILJJIL.LJ.i'L_L. TheLIL." KebenI:L-LILI‘LL‘II-. Ii-I:LITILLSpa. Hotel,I::"I.I..“..11IiI.I.Ino longer!-..‘.IIIL:L.L‘I.-.-L .- I.operating,I_‘IL.IL'LL='_I 113:1. I.L-LLLwas.... '.-.:IL_iIbuilt.: for"IL-_L... L."_..the.ILL: L.L.L.I-.IL“-ILII-.economic.._ _ ,'._ LL.LL"IILLI..L'..L.-_‘Iexploitation. ' '-_.. '__... LLIof"' 1.1.;the. KebenILLLLIL-LLLL -.“iI|.‘.‘II'iLII§_I_I.Spring. A.LLL LILLLLLL'water LILLLLLspecimenIII-:1 II'LLLLwas LLLIIJLLLELLLLIsubmitted I'LL:for LLLILLILLLLLILLanalysis toILL.- theLILLL LILILLLeLLLLLLLIILGovernment (“L-ILLChemist's.LILLI :L Depart-LIL...L I I‘IILLIII.ment in 1945.iii—IF. Thet results,'LL‘fL'LlJ'LiILLL- ILLtogetherLIgLLLIILLLL withI.L-'iLIL L'La partialI.LLLITIILII LLLLIIILLI'LLLILLLLI".comparison ILL':ILLwith L'IIIan LILanalysis'L‘LII'LLIL LILof ILLIC‘L'LI.Vichy IILLILLI'.water, ELI‘I:are ELL-:11given belowi'IfliIIL'JIL’LL’ LL-‘LIIIwith LLa LLLLIIIITIi-I-T}summary LII“of LIIL:the L'LLII-'L:L'LLLILL:L'I:Government {"I'LI:IIIi~LI'LLChemist's LLILLLLI'LL'LIIIL'I-II-L.observations. NoI‘LLI mentionIII-:LLLILLILL wasLI-‘L'LLL madeIL‘LLLLI-.: ofLIL' theLILLL. fluorineIILILLLILLLL content.LLLILL'L I:LLL .' 4U40 HpH'IHiJ “-.'-Lg???" ANALYSIS.‘xhfiL‘IHIH OF1H KEBENHELEFH SPRING W ATER* Keben Vichy parts per 100,000 Alkalinity:':!n:.;ll.-.-1.'.._'r.i..~|r'k3T1-L'lil..Carbonate . . . . . Nil"R fififilr'gfi ‘.‘, -1- Bicarbonateb;L.;;IL1.~LI:1L¢Le'I'-..- -: - ._ . _ _ _ 322.00.w Ln... 560 --.:—_. 1 _. Ammonia:fl- mrvonux.. - -.-. I- Free'l‘fCLn. -...... _ _ _ . {111m0'015 ' " _ ' _- .-".-'. 'h AlbuminoidPuhLLT-zmuu _ _ _ _ _ 0'002want.- -' -1..- r -'I" r '.I.' '_' IE"}'-J'-:-_-:r-.Oxygen gab-aar'cv:absorbed-._|" (4'.'-t hrs.''.iL'."~. at 80°F.)-'.‘"-.| r.- _ _ . 0'03'-.' Nitrates Nil Nitrites Nil H .- _l _. .n' Ill-H. l' Chlorides (asI; C1) 1'0 III L ---. if. +3. _;. :5. ,—. ‘I-u..-' I'FIS- .._ '.II 'J 5:} Sulphates (as S04)J... 0'55 Calcium (as CaO) .. 15'26 36 Magnesium (as MgO) 10,39 7 Iron.. .. 0.1 0.1 Tutu!Total sri-lLa'ijir:soluble au-Liaza.solids. _. ______5313-"352.4 '- '_____ ' _____5 _.-"I -- _ _ - —-. DissolvedIjltr'glffl'cagL. a_CO2In}: _ _ _ _ Not1" ‘-_ 975" measured a. I_.-_I-. -'l -- :-I'. -- '.-I- Hardness:. l-J. Lll_-_-.‘-‘1. TL‘I_I-..Total _ _ _ _ 49'00"l‘ -_r £11.! PermanentE‘Er'mzmcni . _ . . Nil“iii Temporary 49,00 pH 6'7 Analyst: Government Chemist * Laboratory specimen No. 612, received 24th September, 1945 (1) The free ammonia figure is high for spring water and can only be assumed to arise from a harmless source if the possibility of organic contamination can be excluded without doubt. (2)5.. The1th. waterMei-av] containsk.~.-]|'[.'.'..-'|3*~. aL1 considerable-..=1.*~.|‘.L.!._1I.I-_L_. concentrationLl-I'TL ll..!_L‘.:l.'lu of'._': carbon'._..II "..‘.'I dioxide._}-_L"-.-~u-_‘ gas;._-_ the-- '.' . I-‘I' 1 'I'h -' -': '.'.a 'r-h'L- '\- '..-I amountI.!|.'!_1::_ wasHIE-=13": notl-.: determined.'n.-:...-._!Il .!:...L.. +_...-- .-. I (3) The1 .-.L. _'.-_lhardnessL|:-'|‘:""*-1"'-is CINE-"57}entirely temporaryE I u- u dueGIL-L tou calciumtint-.151: andIn: magnesiumrug. 5 L: bicarbonates.M. I: “L" :L-n ' . _ ..‘._..- 1 - 1- ' - 4' ' 1._ :...| _ | !' | ‘.—+!(4) _H'_LThe. predominant[11LLJL'L11.IIJT-:L_.r . saltruin. _ inH?- solutionMllLlH-‘Il. isIr. sodiummumm. .--I 1_-:-L_Lbicarbonate-. . {‘1. L -1I._‘ which_nl L ‘ has-. ~ an alkaline..-.-..r- L.' L reaction,:_'.1-._{JL::L. which'-'-.'._'~..". will'~"~|.l becomehL.L.'-.1.7.'~_ evidentL~l'-..«_'L"'_-I. onlyL'HH afterml; L: the:I'L1 expulsion“I‘d 'wll. ‘I‘. 1"of dissolved-._ “H“ 'II a. carbonC... Jinn dioxide.;aa_;_a:~;:ue:. (5)[5} The ironjmn contentmutt-3n: isEa higherhiahtr'__ thanmar: normally!]L_‘.-:"l‘:1:':H}' presentgi-t'rr-e-‘iw in potable;1-._~.:;';'=:-1: waters.my|.-'-... . It.. isix heldLE‘ILL} in solutionmommy":‘ ' by'tin. thernw:_|.L_ carbon1.1 rhun. dioxidedund‘-' :- gas.4.;5- 7.T. Water-supplyWater—511mm- Water-supply"Waaravumgh.’ provesjumjnu'cn littleH2113: ofUf a problemp'fiifiirm over172W." most:13“: of431' the1h" area,:1':.:. as an'1". adequate'.'.~_!Qi_33_!._l;. rainfall5';-.§11j';1}1 maintainsIT‘n‘Lflfl'fiITré perennialpcrcnnmi springsaiming-rs throughout1h1'L~1:g;_ri-|-JL11 the1h: AfricanAl's'iugnn landilfial andam-z: a:: good3i_h.t:;l flowfima inEr. the'.HC riversFix-urn runningz'unniug offHIT thethn: TinderetTimicrel highlandhighiand mass.IfiLir-H. A.-"'-. numbermunhrr' ofni' bore-holeshum:- hnlL‘n (Fig.{Hg 6){'5'} havehm't: l-l' been drilleddriilcd onum the1hr plateau[fiLflCElL] and the15h: northernmgr-Ehw'n foothillsfunihjlla of111' '1'iraa'.‘.c:';~:.Tinderet, the2hr: resultsream-in beingEvin-.. tabulatedI.=_'LbLl}:1€cfl below. - -- ~~-= I WWII”- T-JJ' g": 4]41 fi O'SO'N .4. H" '1. . .. a. " _ "—— '" H “N? I.I'._C LEI-5;1780 "-.-'\«.ll '0 (1..-.0 - ' ' 85£5. ' '—a .t_ ___ 5:591" |"_'|"'-'_".-'.-2 fl... Upper Phonolite II :3 Wm . I} - --. -- - w - ~ _.r" C[55:1151. Ic1:295“:2092 ” "a“ f - :33 -' 1”: E‘EE . W: LoweraIaI-r PhonolitePhflnfll-fg 633 i w t -' f". t:C 911:1:2153. .ifC:35-5'1S08 iE I ”tRH. .r‘ 't 7" F __.i—H.~_ .- 'H— y}'5‘ . ~._x t-t_.tu., s ‘L:-fi “"t I'*' ._ ..fi- ._ W fl. Q Gneisses[SI-19.1595 of5r '3, v" i 33"“ . I .I' Basement ”'3- Ufipw -D.".L1rr5-I'.'t5 .-_.x 53mm” Ifit .*Rh __.-—al:J- r; --t x-.. .r’1%- u: _ .13: SEND-'1' ' «’- H- . System FL- IF“..- I 3'.‘ -I .-' _ n. ‘H_— -"' i- I ..---~t I “-n‘" —.. I - ' ' t; 1:- ". i .-"I ' F I 'l I m 2 43. .313; 4; .ur-u E ,_ Watt): .n-u r .-" --— - __ q“ an“. ..- '3 H: II“ Flr'I'F 'L/ F _t— —_I'""fi3 “MI J (in! II“ v.31- 3m?FH- M-Ih‘t "'H {in' \XI ' HFJ—J -\'\u u- I. I _- -.-_I "-~-..a“ “‘1 a “ J” fi"M- ,_. 1-K 't'-a”: a“ :I a“. I27“.; a.H Lam:- r a“ I: Ha? r 9.: I Ln “Eda I I ---\"' {WENz lr'x‘l {fa-""3. W: -: bu C IM'2202. ‘, t"*' i“ l .' “La t, .5 ..: rm C: 2051tn- F| I. R , __.-"I "- I'H-_ I .: x ME x Ct 36“”2055. a, 'H- '-I. {ha—J "H -'.'_ "1 Hum “HIE '1‘. '— :II “a .J “a '- “mg" a. “w mm:Tinderel x m ,t “*7-“t It” “a ‘r’c-Ican-tsVolcenics -. I“ \ '. t _fi Gramte {fill :‘I .cif. 1:3!1135 SEPISSES at Hammer-t «’ ' {-aq-‘I'iI-r'l __ _--" _P_.-"' 9‘ I; IT'I “‘t—- ,.» ScaleI1 .-' I'- I'm-“‘1 " '“ .I' \ 'H. '" -. Fa. _.-' ' H5 “-1” _ - '30 5 '-C'|10*1"..E5:MilES '0 .--I “~4- F? a: 'I' I., L ""'"I. J I;'" '~.:ra-r.-.m H r " J/l ~15°F H . _L {charmEquator Fig.Fig. fi6-Position-—PG!-:itinn II’I'of bore-holeshurt—halts in the.the Kapsabet-PlateauKIIIJEIIlJEtuPitHEHu .ElI'EHarea DrillingUniting, Ingalogs furfor tht:the burg—110133bore-holes in thatthe entjtcentire phphonolitefltlfllttt‘ piatcauplateau ureaarea tildiCEtU:indicate that thetltt: lava:L'I‘I'EL coverL‘U‘I’L‘I‘ waswatt probably_E'frl't‘rl“.'_1.li}]}-' piercedpfut'rcd ttttdand the[111: height ofttf the attr‘fL-tcesurface It‘ll:of the1h“ BasementHatamt‘lcnt SystemHyatt-"m rockstackta establishedEfitflbliflhfll at on:one drilling sitesite: uni}.only. 'l'hirtThis isis; bore-holeburg-hula LT.C. 180818% situatedaittuttcti four:twtlr mittwmilf's mutt!,>outh nt'of PlateauPiettcttti stationttinrt whereWh-‘CTC- thethe: in};log indicatesitttiitgtttez-t the followingfit! {It-ting Htlsuccession:-flfiffiiifii‘l; DepthHas?! It Fromr'r'IF'I'} HI ToI If} Ft.f--'- H.Ft. Soil and nutty-antmurram . . . . _ . . 1E . . 12 PhonolitePhttttttlitc ._ ...... 1213 .. 461$468 ElanaSand .. .. ._ ._ . .. 4&8468 .. 4??477 TheTh: heighth fight ofnt' the "sand""Han-ti" must11111312 bebe. about 6,800(hath) feet,tut-:1. but no[‘1t water waswatt tnbtztincdobtained at thhthis horizon.htu'imntt. At:‘it nuno ttthurother bore-holehum—huh: on'JI'F. thatthe plateauphi-tat] Wanwas the phonolitetti'ttttt-fllite bottomedhttzttttttCt] and tiltall watertar-tttttt must b:be Dbtaittcdobtained fromft'mtt fissuredEast-trad lavahut-t ttnt‘tand horizons'Iturizmta betweenhstwccn SLECCCSEE‘IEsuccessive lavalat-'3 flows.flows. flDeepat-g} Wiweatheringflthfll‘tng mt"of rocks[‘t‘tflkri init: the KipkabusKipkiihtlfi are-:1area and of thethe. ttggagglomeratesfin-“31‘.“ tr}; t'ttttlterfurther southinfill-:11 hasham resulted:‘tHLtltCtl in drilling logslttgfi indicatingItttHCEttittg successionsHtjtscmréittttfi Cttttsuirttingconsisting Ettgelylargely tn“of clay,L‘Jat'. tuffstLfij'a and {3:1}:clay withtt-‘Eth boulders.hfiuldt‘l'fi. Bore-holeHint—tut]: L'.C. 1998{LP-ES sitedSitif'Li fourtutti milesmites HtHt—ht-tsouth-westflt ta?of KittkubmKipkabus . II"'" 424E stationraid-Hum pin-pointspin-pviuh the1h: heighthflgh: 31'of the top[Up Ufof [hethe plateauplutmu pih'unulitu.phonolite, indicatingindicalmg *1a [hi-:kncw-thickness ofHf 3-H344 feetfem ofL135 u‘a'm'lyitoverlyingfig agglumumtu.agglomerate. Th:The logEU; ofUI' bore-holeturf—hula: {3368 from:from twoUh? miles[Rik-re can:east of LessosLCHHEE-r-a lakeInk: indicatesindicziich 97l}? feet["rrc‘L of weatheredEir'caihcrmi upper phonolitephnnnlitt and agglumcmtagglomeratefi U‘a'm'ly'ingoverlying the1hr: earliercarhua' phonolite_I‘fi'n'wnflliis flow.flow. AmongAmung theah;- volcanicxulmnk rocksi'L't-L'Ha. ofHi" TinderetIiilLiiji'lfi levelslc'acl'w at.l'! whichwhip]; water'-:~.':I.‘.-:.-:' isin struck:Er'uuk seemaccn'l un-Lit".— predictable.pt‘udiriahk. BORE-HOLESHum -'HI.‘_.1| HS INIn THEiHF. KAPSABET-PLATEAUK--EJH..1E_1E;'I—l’L-x I'[ .‘-.T.' AREA_-"1F=‘.E-_.-x i I DepthDED’Lh K—E'atcrWater I MinistryMinifitry m“of WorksKl'ur'ks. Bore-holeHm'U-hnlr No.Ev. i DateDuh: I DepthFir-cpl}:- wateru-al‘attl' IEW‘L: 6:115. BoredBfli'flfl Iii-ECU struck 51121111level;static I Gals.hour[mm I_ Feet] a: 211:“. J I (feet) (feet) (feet) --1---1------'--- North-eastHLH‘lh—cufl ofn’r' PlateauPliLlLi'LiL'. Station:5mm: rm C._fi. 2090EULJH ...... 25¢ .55 5 r._..-.'| “ND 4;" 33 33111 J — C C- .J- PEI '- .41 1 C. 13361“”-1: J '-_‘_:I ...... _ _ _1""5_. | 5 '1'.— I .._._. I JJ I .I'J 30-1-51 300_g-J 42 35 60 _l'_-.. I .-"'"~ “'II] C..1135.2125 .. ... _ _.. 28-6-531'23—] 5 80 i l—.'42'. I 33 I 280 9-1-54 I 333 290, I - 80 KipkabusHipkzlbus and tom the1hr: south:a-:_":'-._Jt."|: I C.if"- 1322 ..- ... .._ _ 7-10-50T 54;] Eli} 230331'] 198ME; I 16it"! 105H315 I if".C. 133%}1839 - ... . _ 25-9-5225—9—52 200ELM] 65r55 I 4:42 I EDD500 43 15-8-29 295 i 212 12 43 _ _ ii—ifii—ZEJ 29:7. 33;" ‘7‘ i2,400‘ "'-"‘II;‘ C.[fl 1209[2.113%] _ . . _ 19-8-50EL} 5'4 Eli} 35H350 1250:300Iififlffl] 5‘“58 335335. C.IL". 2183315%} . .._ . _ 15-4-54:5 3+ :74 400=‘Hf‘.l{_'] I - - Nil_ C.fl 19981995 ...... 1-6-531—6-53 600fiflfl I 19019H 33031H 303n I C. 1848Lira—.15: _ _ . . 12-10-52.i"-- H} 33 13813:4 109mg: 95Ly:_ 30031;)“ if" ' q C.L1 2050:HEH . . ... 22-4-5322 4 "I 3001mm lfifizlfifl 4E340 1,000l.flflfl f1 _ 1188:250! C. 220222H: ...... 29-4-54I?! i :74 :11“410 SH]280 I 100lLTrE'Ii 31L} C.{__ 20513215‘. . ..- . .. 25-4-5325—445. 300_HTJE'} I 2-1:]240 I 15015E] 55E} I 550 C.{3215.52055 ...... 23-5-5323—5 {'73 2003TH"? I 184'-.~£..1, 80.Egetj: I LIME]:320 tI I 11,200 SouthHuuth of[_13' Eldoret:liidajawfl; i C.‘5-1 1780'73” -- . . 30-5-5215.1.1 F—fi': 4164H":- . :~:5,—.:__:_85:123 10.-;: 13013,3. 85as _ _ 22-7-30:2 7 1H] 355:55 215:15 545-; 375 C.i". 2092It“): ._.. . . . 10-53H] *1 83:~_ -. _ - __ Nil C.{I 151lfll ... . _ ... 15-10-41lfiulu 4] 400.4HU 60:fiflri100flfl - 1201 ! Centre{_"LT!“.:‘.': of12-? theiiis: plateau:;‘-|;'.1L".1L;: t C.E'. 2153 . . .._ . 14-2-54;;.. 100 45 28 i 250 23-7-62 477 I I 220 C.L . 1808:bifJE-i . . . . 3. 5? I 20:11O! 6 '- "1 11 ,: i' " '- "r 1" _"'" C.L _ 2113_1 . . . . 30-11-53. . I .7- 188:-“---”~ I 70“.3 4-“40 I IBM!650 Lessos1.t._'?-I'~§L_EI?~C LUKE-l:area: r . . . 1 I'_'l .-.-. n . . . C.L. 1323I111 . 30-12-50%fi 1- EH 2701:“ ! 136:na 21*. 400in“ -"I - " . -. - .-- -. - - C.a. - 20481.2435 . . . 6-3-53t7: _~ '~ .1 200ZLHJ _ _ Nila .' - - - - -'1 -.- - C.a..- 20491H4?. . . . . 25-3-532: J 53 230:flH - - Nil‘: 68$5 _ _ 16-1-30Efi-i };E 236:35 230:1“ 112*‘ 1,350. Tin 62r131 21-9-29“.1. i} 1.} 37'_‘~'.‘ - - Nilxi. C. 2165 :: I 25-2-541; I * Eng :45 an Elk {j.T?Efi 300 I 145 I 80 500 C.{1 1173IT? .. I 9-10-50U Efl 5r1 400493 95:165:9% 15: i 172.:f 500in. I _II'I -".::' -'_|"- r_ {"1 i ‘III _ I. —-. 1300:390II..- — 1|. —-\.—_ C.-._ 1163i ] '1': 20-9-50_1' ' “1'“: 473'r _‘l 165:460]J 1;“- “I" ll ‘_273' 1- 270_. a__l ;"- '--'*- ‘~ -- . ; ._ 1 n... _I I I | “I- C.L 1222____ 7-11-50 600 90. 204 I 20 Nandi“ma-HT: HillsH I - area:L; C. 1135lit-’3...... I 20-7-50f; _ J 600w.“ - NilL ~ F - -~~== ~-- - ;===-== 43 VII-REFERENCES1r" I l—H’. lili' EREH CHE-i Binge,Hinge. F.F_ W.,1%.. 1%2.-"Geology1LJ62.—”Cnculugy of131'. theih: KerichoHericho Area",.J‘Hrea". Rept.Rep-t. No.Hm. 50,5U. Goo!.{3:01.3L1n'.Surv. Kenya.til-£31131. Dixey,Dix-5:}; F.,F.. 1946.-"The194$. --”I51L= relation1'L‘1;L[iL3n ofu! the1hr: mainnuin peneplainpeneplaifi ofUf centralCcmra'l Africa to[U sedimentsstdin'lcma ofElf Lower[AVE-EI- Miocenehrfimant: Age". Quart.Quart IrmnJour. Geol.Umf. Soc.,Sag-:1. Vol.1’91- CI[I]. (for[fear 1945),H45}. pp.pp- 243-253.243-33. , 1948.-"GeologyE‘HH.-—“Gc£}lug}' m"of NorthernHurlhcrn Kenya”.Kenya". Rept.Rem. No..‘xn. 15,15-. Geol.Gm]. 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Sanders,Hulltiafa L.1.. n.,ll. 1964.-"GeologyILEFr—T. “flaming. m'of theHit; Eldoret135L1m'tt Area"..fi'mf't'él". Rept.Her-*1. No.H11. I‘LL64, GeoI.Haul. Surv.“Liam. Kenya.ham-4. Shackleton,“HELEN-stun. H.R. M.,.11.. 1945.-"GeologyUHF. 1:311.“n miof 31::the Nyerififxcri ant-.1".area". Rept.Rem. No.NH. 12,12. Licmi.Geol. Surv.“Eur-.2 Kenya.Hum-.1. , 1951.-"AWEI—7'3". Contribution{'flniréhutifln to1H the[he GeologyGrinning}. of theth: KavirondoHaafmndn RiftHi2"! VaHey"."w'dEIEjf'. Quart.[ll-Edith Jour.-.I'Ha':'.". Geol.(Mr-H". Soc.,faint. Vol.13.1]. CVI{HE-i (for[hf-3' 1950),]"JEL1|-[1*_T"'-pp. 345-388.345-335.. Walker,REE-.ikur. E. E.,Ir... 1903.-"Reports294.13”. "Hcpmla HE“.on the:31c Geologymining; ofn." thethe EastE-.;-.~‘. African.-"~.!:'.i-.':-.r'* Protectorate".P?.L."|CL".~.'IILL'.:.‘ Cd.{'d. 1769,lTI‘HQ. Africa:‘kl'i‘iua 113i (1903).[E‘JLHL Whitworth,1‘» }151u1:|".‘r‘.-_ 'I'_.T., 1953.-"AICU-:32 ":11-::.1~."_‘.i'.i_*.-':n:urjcontribution to”m 211::the gawk-*3}.geology ofL‘f' RusingaRmiilgn Island,[al.iTiLL Kenya".HMIIWZ'J” Quart.UHH-"J...I'rHH'.{fir-“3.51%...Jour. Geol. Sac., Vol.1 n.'-§. CIX,(— E51. pp.PF- 75-92.Tflfl. * Not consulted in original. G .p.K-:-9TT-1111-4/6T -- - I