GEOLOGINENT UTK IMU SLAITOS (T H E GEOLOGICAL SURVE Y OF FINL AND )
TH EGENERAL GEOLOGICAL MAP OF FINLAND
SHEET B 4 KOKKOLA
EXPLANATION T O T HE MAPO F SURFICIAL DEPOSITS
BY VEIKKO OKKO
H ELS INKI 1949 H elsin ki 194 9 . Y altioneU'lOllon k irjapa iu o CONTENTS
Page PREFACE 5
INTRODUCTION . 7 LOC•.tTION .. . .. • .. .. . •. . .•. •...... • ...... • ...... 7 RELIEF AND LANDSCAPE • . .• ...... •. •. • •...... 7 BEDROCK •. •...... •. .... •...... •. . o P RE-GLACIAL EROSION F ORMS 10
P LEISTOCENE FOR}IATIONS . 12
SURFACE DE THE B EDROCK 12
GL.o\.CIAL EROSI O~ •. . ... • ...... • •. •.. ••...... •. .. • . . 12 'VgATHERI~G •.•• • .. .. . ••...... •.•...... •. •.. • . . ..•. .. . •. . 14
GLACIAL DRIFT 17
T. TILL DEPOS ITS...... ••.•. • . •...... ••...... •. • • •. .. . 17 I?ISTRIBUTION ••• • .• ••. . ..• • • .. . ..• . •.• • .• • ....•. • • • • •...... 17 A CCUllULATION F OR;\I S . . .•...... • ...... • •. .. .. 17 STRUCTURE • • • ', ' . • •• • • .• . •••. • •.• ••. ••••• •• ',' •. • • • • .• • •...... 18 TILL F ABRIe • .• ...... • ...... •...... •...... 20 RA ~ GES O F GRA I~ SIZES • • • • •• • • •• • •. .. • •• • ...... • . • ...... 2 1 LITHOLOGIC R E LATIONS . ..•. . ••...... •• . .. . . • • • •• ...... • . • . •• • 24 OR IGI); • • ••...... • . • •• .. •.. • • . .. • . • ...•. ... •. . . •...... 26
I I . F LUV IOGLACIAL D E POSITS • ••. ••...... ••. •.•.. • •.. ..• ••• •••• 28 DIST RIBUTI ON . • • .•.. . • •••• ••.• • ••• •• •• • . .• . . .. .• •••. •• ...... 28 ACCU?lIULATION 1"0:&:\18 ...... •• . .• • ...... •• • . • •• 29 STR UCTU RE •...... • •. •. •. •• ..• • .• •.• •. .•...... • . • • . •.. . •. . . 20 R A);GES O F GRAIN S IZ ES ...... •• •• •• • • • ••••...... • . •. • 31 LITHO LO GI C CO)IPOSITION •. ... • • • •• •• ...... •. .. . •• • • . • _ _ .•.• • . . 32 ORIGIN • ••••. • .. . • •••• ...... • . • .. •. . • •..• . • • • •...... •. . 33
S II ORE FOR ~f ..\.TIONS . :34 '''IND DEPOSITS • ...... • ...... • ...... 35 SILT AND CLAY DEPOSITS . 38 ALLU'YIAL DEPOSI TS • •• •...... • ...... •...... 30 CHEl\I I CA L SEDlI\iIENTS ...... • ...... • 40 S HELL DEPOSITS .. ..•...... • ...... 40 S UBSURFACE 'VATER 40 S OIL PROFILE • ...... •• . .•...... 41
'!.355 / 4 11 4
PEAT DEPOSITS _ ...... 4 1 n I ST I~ I n UTJO X ...... • • . . ..•. •...... • ...... " 4 1 PEAT TY P F.S ...... • . • ...... 42 eTl PI~ F. I STOCEX F. DEYELOP:\IEKT 47 MO\ 'EME:s'T AK D MELTI 1\G OFT H E I CES HE ET ...... 4 7 CHANGI NG OF TH ES HOR E-LINE ...... 4~ D EVELOl'I\IENT OF EME R GED LAND . . . • ...... 50 PH E HI STORIC SETTL EMENT AND TH E RETREA TI NG SHORE .LIX E ,, 0 CI\' ILIZA'l'ION AKD SURF ICIAL DEPOSITS ...... " I INFL UEN CE OF D EPOSITS ON THE P R E SE NT SETT LEl\ IE :XT 51 T ECHNICAL e SF. OF DE POS ITS ...... ;. 1 LTTE HA'ITRE 54 PREFA CE The geological map of Kokkola forms sheet B 4 of t he General Geological Map of Finland. In t he year 1932 a map of pre-Cambrian rocks of t his area was published on t he sa me scale as t he present map of surficial deposits. The mapping of both map s was done by the same geologists at t he beginning of t he 20t h century. Therefore t he mapping of surficial deposits follo wing old methods is not quit e applicable in allmodern desiderat a. The combining of t he field maps was ent rusted t o Gunnar Brander Ph.D., but his death on 11. 3. 1940 during t he Winter War put an end t o his work. Before the war Brander had, however, time to draw t he map of surficial deposits for print and t o carryon revisionary invest iga ti ons on the mapp ed area, bu t t he man uscript for t he explanat ion was broken off at t he beginning. When in 1946 the present writer undert ook to proceed wit h Brander 's work, he availed him self to a great extent of the material collected by Brander . The map sheet of Kokkola (B 4) presenting surficial deposits is published in t he shape already planned by Brander. The scale and the colours are t he same as used before, except t he new colour , orange, t hat marks alluvial depo sits. This innovation was suggest ed by Brander. During t he work of revision in the summer 1!)46 and during t he printing of t he map only some small admen dments were made to Brander 's map. On the other hand t he explanation to the map is ent irely rewritten. Now t he outline is new and also the contents, because an attempt has been made t o pay more attent ion t han before to general features, structure, genesis, an d to t echnical purposes. The first-ment ioned view points are in t he fore- ground in t his paper, as t ech nic al use is of more local importance. It has been more widely dealt with in the explanation writ ten in Finnish . During t he revisionary investigations carried out in the summer 1946 a special at tent ion was paid to peat bogs, t heir dist ributi on, peat kinds, an d to t heir technical uses. In this work ~Iart t i Sal mi P h.D., Forester V. E .Valovirta , and Mr. A. Leino t ook par t , whereas Mr. Leo Heinonen , ~I.A ., helped the wr it er in his revisionary investigations concerning the mineral deposits. Geological Survey of Fi nland, J anuary 1949. Veikko Okko. INTRODUCTIO}l LOCATION The sheet B -1 presents" triangular sect ion of the E coast of the Gulf of Bothnia (F ig. 1). The SE edge of the map lies " bout 65 km. from the Fig. 1. Locatiun of the mapped area. shore-line, which runs from SW to NE, dividing t he sheet into t wo p arts. Thi s is the reason why only thc SE part of the map sheet is dry land. R ELIEF AND LANDSCAPE The landscap e is chiefly characterized by flatness. The map illustra ti ng heights (Fig. 2) shows t hat t he t errain rises very slowly from t he coast towards the interior. In t he SE part of t he m"p there are already heights over 100 meters above sea -level. A larger part of t he sheet belongs to t he altitude between 100 and 50 met ers. I t proceeds across t he sheet as an about 25 km. broad zone parallel to t he coast. The proper coa st region is made up of t he 25-20 km, wide area sit uated below t he altitude of 50 meters. The harmony of the three height zones indicates the flatness of t he t errain. The flattened relief continues also under t he sea- level, as is shown on t he maps presenting the depths of the Gulf of Bothnia. The raggedness of the shore-line, the wi nding course of rivers and of cont our lines in some places point to t he local uneven surface . According to t he geographical divi sion of t he landscape (Grano 1931) the map sheet B -1 contains parts of three different landscape types (Fig. 29 p . 42): 8 20 .70 . QAAJ.I. "f • 100- /50 ~ .50-100 0 0 - 50 ' - Fig. 2. Relief. They are : I. River landscap e o] Ostrobothnia, 2. H ill y landscap e o] 8 1101ll en seik«, and 3. Plain landscape o] Routh Ostrobothnia . I. The NE part of t he map sheet belongs to t he river landscape of Ostrobothnia. This is mainly flat , especially along t he rivers. The relative heig hts are belo w 10 meters. T he divides between river valleys with their drumlins and rocky hills rep resent t he most uneven surface. 2. The hilly landscape of Suo menselka stretches from SE to the coast in the middle of t he sheet. The area is characterized by an irr egular 9 microrelief, where the relative heights vary from IO to 20 meters. Its influen ce is to be seen in the contour lines and in the shore-line. 3. The plain landscape of South Ostrobothnia begins in the SW part of the sheet. It rep resents t he most even area in the map. The relative heights are t here below 10 meters and t he plains containing post-Glacial deposit s pr edominate . BEDROCK The bedrock of t he map sheet is composed of pre-Cambrian rocks (Fig. 3). They have been divided (Sa ksela 1933 ) into a supercrnstal formation and t wo series of igneous rocks. GI:lni!e and granodiorite J • porphyriti c ) Hornblendc·granodiorrtc I Diorite younger } l'u"t· Gabb ro I Buthnlan Pc riu :Jtitc Diabaose ·lllor!'hyrite ) Prgmll.t1tc and muscov ite granite "\ • " , migmatitic I , older , post Bothnian GJlf'l""f)~C granite . . migmatil k ) Iliotlte 1,!ag iol;lasc gllei:;.~ ) • • m lgurat.ltl c q uarl zitl', j-artly mlgmatitlo B othnian super- Ha..tc d fusi vc'" .Black sch!J.;t". Fig. 3. Distribution of rock kinds (Saksela 1933). 10 The supercr ust al formation cont a ins mainly fine-grained biotite pl agioclase gneisses , whi ch are mostly migmatiti c, mica schists, qu art z ites, lept ites, and two small exposures of met amorphic limestone. I n connection with these there are also s mall occurrences of more or less metamorphic basic effusives, viz. a m phibolites, diabases, plagioclase porphyries, a nd agglomerates. The intrusive series of igneous roc ks consists of granites, diori tes, gabbros, and peridotit es, which chiefly belong t o the olde st series. The rocks of the youngest series are mainly m icrocline granites and grano dior, ites, PRE·GLACIAL E R OSIOX FO RMS Exposed rocks concent ra te t hem selves in the N and SW part of the map sheet, but also in ot her pl aces bosses of rocks projeet t hrough the surface here an d there, both in the river valleys an d on t he divides between t hem. The nearness of t he bedrock indieates that t he relief is cause d by t he surfa ce of t he pre -Cambrian bedroek. T his surface descends .very slowly fro m the }nland t owards the Gulf of Bothnia. It for ms a slig htly inelined peneplane, where t he points of the greatest resistance are not so much worn out as th eir surroundings. As an example may be menti oned t he quartzite rock Hopeakallio in t he parish of K iilvia , wh ich lifts its sum mit at the altitu de of 30. G meters on the sea coast . The granite areas in t he middle of the sheet appeal' to have resisted erosion t o suc h a degree t hat they have not been abraded by t he glaeier as mu eh as t heir neighbours. The agglomerate ridge in t he E part of t he sheet forms a n area of the same kin d , the course of which follows the common strike of that ro ck . Pre-Glacial erosion has, however, generally worn out to an almost stro ng degree all ki nds of rocks, t he relief of an area scarcely differing fro m those of other areas . This is proved, for instance, by t he fact that t he flow directions of t he ri vers cut rock areas almos t arbitrarily . T he biggest rivers, Pyhajoki, K alajoki, and Lestijoki flow to wards t he sea in the pre-Glacial v alleys. The broadly flaring profile (Fig. 4) of t hese valleys indicates t hat t he valleys are formed by strea m erosion . Pre-Gla cial erosion forms can also be observed in t he sculpture of the ex posures of t he bedrock. Plut onic r ocks with granitic texture have roundish forms and t hey slope symmet rically in ever y direct ion. The in clination of the slopes depends upon t he kind of rock. Gabbro and peridotite rocks descen d steeper t han granite and diorite ones , which beco me det aehed in t hick shells parallel to the surface (see i. a. H ausen 1944). E xfoliat ion is most effective on fine- and middleg rained granite, whereas pegmat ite granites form more irregular hills with steeper slopes . Gneisses and other metamorphic rocks wi t h parallel arrangement of 11 'J() '" 4 Llo 4 ' 4 ' ,(l,. "0 ______~ L e s t lj oJt ; 8 6 2 m.y.m.p.__ f • • 2.0.-6 .J : :: '" ==== () ' 00' 100 .100 'D()Orn Fig. 4. Wide river valley of Lestijoki near Ahola, Toholampi, filled up with sediments. Photo and levelling by G. Brander. In cross-profile 1 = stones, 2 = moraine, 3 = alluvial deposits. and 4 = clay. t heir minerals form longitudinal ridges in the dire ction of t he comm on strike of t he stra ta. The strong erosion, which took place on t he surface during the pre Glacial time, must have caused masses of weathering and erosion products, but t hey have not been found in t he mapped area . It is obvious that t he pre-Glacial stream erosion ' removed one part of t he m, t he ot her p art having been ero ded by the glacier . The abundance of errat ics indicat es that during t he Ice Age t he su rface of t he bedrock was shattere d into eracks and crevices . Mechanical disintegration may have started from t he tectonical broken lines and from t he innate tende ncy of rocks to break, because both of t hese phenomena have as early as in t he pre-Glacial ti me crushed the bedrock (Sederholm 191 3). It is indeed very difficult to determine t he age of the cracks, as only in two places could it bc stated that the glacier had pushed forward over t he cracked surface. There t he glacial erosion had polished the opposite angles of the crac ks . Mostly it was impossible to find any t race of glacial erosion in the sharp edges of crevices. PLEISTOCENE FORMATIONS SU R FACE OF THE BEDROCK GLACL\L EROSION On the surface of t he bedrock traces of glacial erosion are more dominant t han pre-Glacial forms. The knobs that resisted the glacier movement are smoothed and polished , whereas the un supported lee-sides Pia, 5. Polished rocks, Yastersund, Pietarsaari. Abrasion took place from the ~ direction of 320°-330°. Photo V. Okko. have eit her kept up t heir sculpt ure or have become more irregular by quarry ing and plucking. T he surfa ce has t hus got au asymmet ric arrangement , stoss-and-Ieo topography (F ig. 5), t hat point s to the movement direction of the glacier. On t he stoss-sides there are also other evidences of t he ice flow. Such evidences arc glacial striae, grooves, and friction cracks (Fig. 6). Part of t his mate rial has been publish ed earlier (Lciviskn 1907, Hclaakoski 1943), but most observations arc made during the mapping work.The majority of discoveries is to be fou nd on t he coastal region, because the surface of t he bedrock is there less weathered t han elsewhere. The most co mmon traces of glacial erosion are the striations. In some places t hey for m very fine scratches on the clear surface of pegmati te quartz, whil e in ot her places t here have been met wit h glacial striae more than t wo meters long. The co mmonest type of glacial striae consist s of uniform line sys t ems on t he stoss-sides. By aid of the pa rallel 13 2 ' r- I 28.5-300 ' .IL 32.5-3«7' I Jff .145 - 360 ' st riaet ion it has been possible most exact ly to determine thc flow direction, whi ch gave the polished roeks their sculpt ure . I t seems obvious that both t he sculpture and main striaet ion were formed simultaneously . In t he N part of thc map there are foun d in many places crossing striae, the dire ct ions of which change between W-E and N-8. This inconsistency repeats itself on t he coast of Kalajoki, Hi manka, and Kok- 14 kola, but it has been met with on some r ocks also in t he interior. Crossing striae occur eit her on the same surface where t hey cross each other (Fig. 7), or on different erosion fac es forming discordant trends. The examina tion of crossing striae and other erosio n marks (Ljungner 1932) shows Fig. 7. Crossing st riae, Ypperi, Kalajoki. Detached striae from direction 345° cut the earlier system from direction 285°. Photo V. Okko. t hat t he change in direction is not accidental, but t hat t he diffe rent sets and striae systems have here a distinct order of age. It repeats itself at every observation point where it has been possible to establish the relative ages (discoveries wit h numbered arrows in Fig. 6). Friction cracks are very rare. They are found in two places , . where they form gro ups of narrow, cresce nt -shaped curves in finegrained and hard rocks. In both cases t he conve x side points downstream. WEATHERING Post-Glacial weathering of the bedrock can take place almost ex clusively on rock exposures, where it appears as two different kinds, viz. decomposition of rock and mechanical disintegration . Decomp ositi on of the surface cause d by the dissolving of different minerals is here quite insig nificant and depends intimately upon the type of rocks. The surfaces of qu art z veins and t hose of feldspar crystals in peg mat ites are st ill quite unchanged , whereas basic rocks rich in iron 15 have been covered with brownish , weathering crust . Th e thickest weathering mant le, about 30 em., has been met with on the peridotite of Kunnari, in the parish of Alavieska. When comparing the surfaces of the same kind of rocks, it seems t hat t he weathering mantle increases Fig. 8. Disrupted rock, Kalliokangaa, Toholampi. Photo Y. Okko . from the coast to the inland. This is easy to underst and, as the low located rocks of the coast have recently risen from t he sea. Occasionally, however, t here is found in the shore level intensive decompositi on of the surface, cau sed chiefly by the dissolving of Ca-bearing minerals . One reas on for this phenomenon "may be the laud-upheaval, which has diminished t owards recent times 'and lets the weathering continue at the sea level longer t han earlier was the case . Mechanical disintegrat ion is caused by the expansion and contraction of rocks owing to the changes of temperat ure and freezing. The effect is most not iceable in granite and granodiorite areas.Rocks in favoured positions are disrupted in blocks (F ig. 8) and belts of jagged rocks (F ig. 9). The immediate proximity of blocks, the corre sponding fa ces, and the same ro ck kind confirm this opinion. The zones of exposed rocks have t hus often been disrupted t o long mounds of sto nes. The absence of vegetation, t he angular for ms of blocks , and t he new-born crevices (Fig. 10) show, that mechanical disintegration still continues. In many cases there is water bet ween the blocks even in midsummer, because these jagged rocks lie on an impenetrable base. 16 Fig. 9. Belt of jagged 'rocks, 8,3 km. from Kannus church village towards Eskola, Photo V. Okko. Fig. 10. New-born crevices, Rautio church village. Phot o V. Okko. 17 GLACIAL DRIFT 1. TILL D EPOSITS (" ONSTRATIFIED DRIFT) DI STRI BUTI ON Nonstratified drift or till ha s most widely distribut ed of all surficial deposits in the map sheet of K okkola. Till reaches to the surface on t he areas coloured blue on the map. Elsewhere t ill is buried under younge r depo sits and for that reason t he map does not give a right view of it s distribut ion . The whole blue are a is not, however, covered with t ill , but contains also shore dep osits. Instead of t his the map shows that till is the most common minerogene deposit on the divides between the rivers and in some regions on the coast, where it forms the surface , as depressions have not had time to become bogg y. The largest intervals bet ween t he moraine areas are caused by deposit s, which fill up t he river valleys and t here cover t he t ill. In spite of its "ide distribut ion, t ill veneers t he bedrock as a fa irly t hin mantle. The numerous exposures of t he bedrock give evi dence of t his. In the N part of the map sheet , as well as in t he neighbourhood of t he town of Pietarsaari, the t ill layer is seldom more t han one meter t hick. In the inland it s t hickness increases to 4 or 5 meters. ACCU:\IU LAT IO:N FOR:\IS x[oraines - built up of till - can be classified aecording t o various topographic forms. In t he map sheet there have been found qround moraines, drum lins, end moraines, and death ice topography. As t he drift is mostly t hin, it fails t o mask t he irregularities of t he bedrock. T he surface is t hen smoothed an d reflect s t he relief of t he bedrock.The moraine in such an area has not its own accumulation forms. This moraine type is of widest distribution in t he mapped area. Where the drift becomes t hicker its surface begins t o acquire its own to pography. T he most com mon for ms are drumlins, t hough t heir dimensions are not so great as in E and N Finl and. Drumlins concentrate t.hemselves here in t he hill y landscap e of Suomenselk a , but in t he river landscape of Ost robothnia they are not r are. The to ps of drumlins project there from t he sedimen t bed in t he river valleys . Inland, where t he drift is t hickest , drumlins att ain t he height of 5-8 meters. The long a xes of t he dru mlins are parallel with the st oss-and-lee t opography of t he bedrock. End moraines are very rare and they no where form coherent ridges, which often point to the locat ion of the ice margin. Such ridges as have been supposed t o be end moraines (Leivis ka 1907) have a long direct ion 3 '!. 355/!!J 18 SW-NE. F or that reason t hey may form marginal t hickenings of the ground moraine. Death ice to pography occurs on sma ll, well-limited areas in t he flat landscap e where t he drift forms irregu lar groups of ridges and hillocks . Some of the ridges have a cert ain long direction , but to the same complex there belong also transversal ridges, binding t oget her the first-mentioned ones and causing a net-like to pogra phy . The small kettles and micro valleys int ensify t he irregularity of t he surface. ST RUCTURE Till is a deposit"that has not been assorted and for t hat reason it contains different grain sizes , ranging from boulders to clay in varying combinations. After the accumulation of t ill secondary transformations have occurred in the topmost part in such places where till forms the surface. They have been cau sed by t he work of waves, by freezing and thawing, and by forming the soil profile . Till varies also locally. Thi s is caused by lenses and thin layers of st ratified drift , by the st ru ct ure of t he till it self, by t he regional changing of gra in sizes , and by the lit hologic composition. The surface already indicates the distribution of t ill types rich in boulders and poor in boulders. The former t yp e pre dominates in the main part of the map sheet , while the lat t er is found in the SW part of t he area . Till is also characterized by an unstrabified and fairly loose struct ure . An except ion is formed by a compact clayey till found in some places in t he N part of the map. The t ill is there hard pressed, it s st ru ct ure being a cons equence of the pressure of t he ice sbeet. In the inland till is chiefly looser and coarser, but it also has a pressed st ruct ure , changing in t he sandy till into t he parallel stru ct ure. It is also characterized by t he arrangement of t he st ones, the long a xis of which is parallel wit h t he structure. This type of fissility (Fig. II ) is common in t he main area of the map sheet. There are in t ill also t hin lenses and band s of sand, which form mostl y well-limit ed figures. These do not make up any coherent layers, t he len ses of sand occurring scattered here and t here. D ri f t o f K o k k a I a . In the SW part of the map sheet t here is an except ional t ype of drift described by Soderholm (I 887) and by Brander (1943). Its surface is est her stony, consisting of separa te blocks, or is almost sto neless , loose deposit . Blocks and stones are concent rated in "t he upper mos t layer. Deeper down they get rarer, and the deposit is composed of lig ht fine sand , in which there occur sand and silt bands , 19 Fig. 11. Parallel structure in till, Peitso, Kalviii. Photo V. Okko. and bands of colour caused by iron solu ti ons (Fig. 12). This light and loose deposit , rich in fine sand, is likely to extend to t he bedrock. . The fine sand is well sorted and st rat ified, as it is the case with deposit s accu mulate d by wind or by flowing water. It cont ains, however, so me separat e block s and boulder s. Near F rost, in the N part of the parish of Munsala , this st ruct ure changes t o a peculiar breccia , where roundish , oval , and compres sed balls of sand alt ernate with less sorted and more den se matrix of fine sand and silt (Fig. 13). Another »breccia moraine» of t he same kind has been found by Maki nen in t he vill age of Leppalahti in the parish of Piet arsaari. In many places t he fine sand deposit extends te t he surface, but some times, as by Rodso road in t he N part of the town of Kokkola, and in F orsby of c · . t he W side of the road Fig. 12. Drift of Kokkola, Alaveteli. Photo G. Brander between Pnn nainen and (Brander 1M3j. 20 Fig. 13. _Breccia moraine. near Frost, Uusikaarlepyy, Photo Y. Okko. the Purmo church , it is covered with nonstratified sto ny t ill t hat is steeply limited to t his sandy sediment (Fig. 14). In t he N part of t he map sheet there i ~ also found in the parishes of Pyhajoki and of Alavieska till-like man t le over strat ified drift. TILL FABRIC Investigations made in different areas (Richter 1936, Holmes 1941, Kivekas 19·!G, H yyppa 1948, Lu ndqvist 1948, Virkkala 1949) show that the long axe s of rock frag ments imbedded in t ill are often parallel 'li th t he trend of glacier flow. In 1946 so me analyses of t ill fabric were made also for t he Illap sheet of Kokkola. At every point of observation one main directi on could be regularly ascertained. These t rends are drawn in Fig. 6 with dotted heavy arro ws (the dots of which indicate Fig. 1-1. Contac t between stony till mantle and fine sand deposit, Forsby, Pietarsaari. Photo V. Okk o. points of observat ion). In 21. the N part of the map sheet the arrangement mostly parallels the glacier flow, from WNW to ESE. An exception is formed by one analysis (on t he road Pyhajoki-e-Oulainen 14 km. SE from Pyhujoki church) , where the trend according to Heinonen is N-S. In the main area the orientation of till"is from NW to SE. The re sult of one analysis made"in the death ice topography area in the SE part of the map sheet differs from this direction. .It points to a maximum W- E which is t ransvers al to the long direction of a local ridge. RANGES OF GRA.IN SIZES '. The s u r f a ce 0 f t i l I is usually covered with vegetation. Only stone fields, jagged boulder rims, and erratic boulders a:re visi ble. They are concentrated in the middle of the map sheet , where t heir occurrences continue from the coast between K alajoki and Kokkolato the p arishes of Sievi and of Toholampi. In so me places t he cover of st ones and boulders is fairly unbroken (Fig. 15), but generally the amount of stones and boulders is normal, growing only in small areas to coherent st one and boulder fields. These are situated on irregular moraine terrain. Stones are concentrated on the tops of moraine hills as bars and on their gentle slopes as rims. Both belong to shore deposits, although their material is primarily till. Boulder fields are found as results of quarrying near .t he exposed bedrock, as boulder rims in ancient shore-lines, and at the bottom of depressions, where they are enriched by frost. Erratic boulders are often so big (the biggest 12 X 10 X 5 m.), that it is diffi cult to find out, whet her they are lying in situ (Leiviska 1907) or whether they have been t ransporte d by ice . The erratics occur either as separate, fairly fresh boulders (F ig. 16) or as boulder groups, composed of several blocks (Fig. 17). In such a group Fig. 15. Moraine covered with blocks, Luikku, Kannus. the blocks lie quite Photo G. Brander. 22 Fig. Hi. Big erratic boulder lying 200 J11. W of the Rautio esker. Photo G. Brander. Fig. 17. Big erratic disrupted in block s, Pentin silta , Lohtaja. Photo G. Brander. close to each other and t heir faces are so similar that they must have disrupted in blocks on their present locali ty. It is evident that during t he Icc Age t here were in the bedrock places with joints and with other marks of disintegrat ion so that the glacier could quarry out big blocks and carry t hem for at least a short distance. Th e i n tel' i 0 r 0 f .ti ll is less stony t ha n the uppermost part. T he main component consists of a gra yish brown sand and fin e sand gro undmass, wi t h dispersed separate rock fragments of varying size and shape. These are often angular and on their faces glacial striae can he noted . 23 , ,. In t he groundmass fractions • . less than 2 mrn , pred ominate. V The average curve, based on 60 A 28 mechanical analyses, shows ~V in Fig. 18 how this grain size is divided into different frac tions. An except ion to t he com W mon type is made by the drift ct: of Kokkola, becau se it contains '0 t;::? more fine sand (curve 2) , and ~ t::-:::: by t he compact t ill (curve 3), o Fig. 18. )lechanir.al compositio n of ground-mass where t he share of cluy is more in till. 1 = average curve, 2 = drift of Kokkola, important t han usual. Fig. I D 3 = compact till from Ypperi, Kalajoki. 2 ' " ' >o " 7,,5 X~, ~ ' 0 Ka lqjoki + I I J Fig. 19. Regional distribut ion (If grain sizes less than 2"mill. in ti ll, 24 illustrates the regional distribution of g r ain sizes less than 2 mm . in till. With the ex ception of some occurren ces of sandy till (7, 9, and 13), till everywhere mostly consists of fin e sa nd. This grain size predominates in the Kokkola drift, whereas the sum of silt and elay is most abundant in the northern part (1- 5) and in t he Toholampi area (24-26). L IT H OLOGIC R E LATIONS In most eases erratie boulders eonsi st of t he same roek kind as t he local bedr oek. Some times, however, t he same roek kind is found to the NW of a discovery point of erratic. It thus seems evident that at lest some of t hese boulders have been carried to SE. In the N part, of the map sheet, in the parishes of Alavieska and Merijarvi , a t ransport of t ill to t he sa me trench has been stated (Laitakari 1937). The till in t he village of Somero (t he parish of Alavie ska) has come from the compass bearings between 290 -350' (expressed in azimuths). The boulder train of the K unnari peridotite on t he NE border of the map sheet has at first t he direction 120', but little by little the train becomes wider and its wings take the directions 109 and 130'. In transport by glacier till was mixed up . By comparing the lithology of t he till in the village of Somero - where rock kinds have been determined on the ground of 2 000 boulders (Lait akari 1937) - with the pre-Cambrian map of roeks, t he average length of transport has been calculat ed (Kivekas 1946). Boulders from the local bedrock totalled 19,4 per cent, which toge ther with boulders transported altogether less than 10 km. formed 31 ,4 per cent, boulders carried from 10 to 20 km. formed 28,,4 per cent, and such from a distance of 20-22 km . 37,2 per cent. The rest, 3 per cent , represents boulders from unknown sources. To these belong i. a. boulders of sandstone, the occurrences of which lie at the bottom of the Gulf of Bothnia. • Lithologic relations of the bedrock arc illustrated in Fig. '20, which shows combinations of stone counts made of st ones the diameter of which is 5-10 em. The figure indicates, that t he lithologic relations in glaeial drift change according to the bedrock. In t he wide migmatite and gneiss areas of the sout hern part these rocks reach their maximum also in till (stone counts 18-20, 24-26, 30 , 32), whereas in the granite are a between K alajoki and Eskola (8, 12, 21, 22) and in Toholampi (35 and 36) granit e forms t he chief eomponent in till. The influence of the loeal bedrock is st ill clearer in st one eounts made in the gabbro and diorite areas lying S of the town of Raahe (1, 2), in the peridotite are a of Ala vieska (9), and in the leptite are a in the same parish , as well as on t he schist zone between Kalajoki and Sievi (13, 14, 16). 25 2 · if' "Ok~ 0 10, 20, J O 1 5 ~ 2 ,,+ + .J 2 Do , 3 D• 0 0 0 4 ~ 6 1+++++++ 1 6 0 7 - Fig. 20. Combination of stone counts. Stone count sectors: 1 = granites. 2 = hornblende granites and -diorites. 3 = gneisses, 4 = Ieptit es, 5 = quartzites, 6 = basic rocks. Bedrock: 2 = granite, 3 = hornblende -granite and -diorite, 4 = gneisses and migmatites, 5 = Ieptites, 6 = quartzite, and 7 = basic effusivea. Underlined sto ne counts indicate lithologic relat ions in stratifi ed drift , others in till. In some stone counts t here are also separate roek fragment s the source of which does not lie in the mapped area . Such are pieces of sandstone, mudstone, white or light reddish quartzite, white dolomite, and certain diabases.As t he frequency of these increases t owards the coast of the Gulf of Bothni a (Fig. 21), it is evident, that their sources are situated under the sea. 4 23 55/4-0 26 so- Raulio+ TonOlomp i1" CD• " Fig. 21. Percentage of stones originated Irum the basin of the Gulf of Bothnia. 1 = white or reddish quartzite. 2 = dolomite. 3 = sandstone and mudstone, -1 = diabase. ORlO lX The unassortedncss of till, a ngular s hapes of rock fragments as well as their striaetcd fa ces are evi dence of the glacia l origin of t his sediment. Fur t hermore , t ill fabric and lithologic rela t ion s indicate that t he material has been currie d by t he ice flow to its present localities. In transit t he load has been mixed up a nd crushe d. T he distribution of boulders, wh ich have been transported from certai n sources, stone counts , and t ill fabric sho ws analogou sly thut the main transport took place si m ult uneously with the strongest a brasion or during the first ice flows. 27 T he similar distribution of g round mo raine indicates t hat in t he wh ole area t he load carried by glacier was ne arly the same quantity, as the glacie r proceede d on a fai rly wellsmoothcd peneplane . It seems prob able t ha t t he basal part of t he ice with heavy load beca me adhered t o the floor in It subglacial posit ion as soon as t he t ransporting capability of the gla cier began to diminish (Ahlman 1938, Lundqvist UJ40). After getting free fr om the load the ice lllU)' have moved a nd h as perhaps given t he finis hing touch to thc drumlins (Ebers 19:17). One p art of the load has not accumulated until at the ice m argin. The structure of the Kokkola drift, its mechan ica l composition, and especially the miorofossiles found in it point to s uc h orig in. According to Brander (194:l) they are ev idences of an inter-Glacial period, but t he investiga tions made by H yyppa in 194 6 (unpublis he d) a nd by t he author in t he same year indicat e that t he microfossiles are of the same type as in late-Gl acial se diments elsewhere in South Finla nd (Hvyppa 19:17). T hc' pollen flora m ay be illustrat ed by the following examples: H:up df'cid lll>US tJ('t '5 i l ' i ll" ~ Bet ul a Ainu .. nnm", T Hin I 1 \ For sb v. Pi etnrsnari . ·· 1 4U 3 I:; 71 i 1:1 I :2 I » .. ." 100 1 4 84 I Jl \ 3 >, l} •• • lGO 1 :l 84 12 , 4 I '/ " 1 200 I 2 72 :2B 1 :, [) " " 250 2 3 Sf} 10 Ii J> >} . .• 450 1 1 8f) 12 1 I 1 . Rddsa, Kuk knlu ...... i 1)0 13 2ii 44 17 2 ; >} ,. 1 80 7 20 60 13 I a " .. :::::: HiD 8 :W 64 7 1 spec. :2 spec. , 4 I'" ,. I 2.fO I 5 II ,. • ••• •• 1 280 VI ,...s 12 I fl I II I) ...... 2HQ I 22 71 s 'I 7 i . • ...... , 3111 14 7~ III 8 I " ,.···· · .1 320 1!l 162 11 Anal yst : K . Salminen . T he di at om flora consists, besides of fresh wat er di at oms ( .llelosira islandica spp . heloetica, M . qran.ulata}, a lso of some salt wat er species of the genera. Coscinoiliscus, Gra mmatophora a nd Rhabdonema. T he same forms are charact eristic of lat e-Gl a cial sea sediments, deposited in front of t he ice margin, us d uring the deposition of the sediment sen. water was mi xed up with fres h melting water. On t he other hand, the folded , in SOUle places breccia-like structure and st ony m antles on t he drif t show t hat t he glacier has pushed fo rwa rd over the se dime nt s. T hi s last progress may be caused by t he flow from the no rth, because the youngest st riae in K okkola have this trend. Alrea d y in 1910 Makinen assumed t hat t he glacier had here advanced O \'Cf frozen sand dep osits and t aken bi ts of t hese a long in the ice flow. 28 On t he NW side of the Gulf of Bot hnia a similar deposit , K ali x.pinn mo, is found, which has bcen explained (Bes kow 1935, Lundqvist 1943) as a result of ice oscillation. I n the Kokkola a rea there is, ho wever, one p art of t he sediment still in its pri mary positio n . In only a few p la ces is t he sediment mixed up again for ming a ne w- born glacial drif t . I n other pla ces t he sediment is covered wit h a till-like mantle. Dea th ice topography as well as possib le end moraines is built up in the marginal zone of the ice shee t , when t here has been more load than commonly was the case. The arrange me n t of end moraines shows that the margin of the ice sheet had the general tren d from SW to NE. The small knoIls and ri dges of the death ice t opography are composed of tiII enriched in a fla t t errain. During t he depositing of till there a mass of ice blocks wa s buried in same. These ha ve lain wholly imbedded in ti Il and close d depressions as weIl as smaIl k et tles now mark t heir ancient locations. Under such conditions the ice must have been stag nant (F lint 1042). II. "LUVIOGLACIAL DEPOSITS (STRATIFI>:D DRIFT) D ISTRIBUTIOX Su ch pl aces, where fluvioglacial dep osi t am si tu. extend to the surface, are marked in green on the map. These occurrences form on the SE part of the shee t narrow chains, lyi ng one beh ind the other in t he ge neral directi on from SE t o NW. Very often the green bands are bordered with are as of gravel, Band, and fine sa n d, which are coloured lighter green on t he map . I n t he inland the borders are narrow, but towards t he coast they become wider . Almos t all sa n d areas join to the occurrences of Iluvioglaoial depo sit s. The light green coloured area chiefly includes fluvioglaeial material , which has later been spread and assorte d by t he work of waves. Due to t his fln vi oglacial deposits are in many p laces covere d with shore sand . The distribution of fluvi oglacial drift ca n thus be cons idered on t he basis of the co mmon occurrence of both colours. Thus understood, fluvioglaeial drift for ms here much more coherent and mu ch longer chains than the dark green figures indicate. The longest chains cross the map sheet from K au stinen to Yk spihla ja and from Ull ava to Lohtaja. The third chain is made up of a sa nd area, stretching from Eskola to Kalajoki. Furthermore t here are between K au stinen and Herronen, in Sykarainen, and between Sievi and Rautio fluviogl acial deposits, lacking sandy extensions. AIl these last-mentioned belong to the SW ends of the long esker chains tha t are sit uated outside the map sheet (Brander 1934). 29 A C C U ~ I U LAT IO K FO R:\IS The most com mon typ es of accumulati on forms of fluvi oglacial deposits: long ridg es with narrow t ops and stecp sides, the so-called es kers , arc rare in t he map sheet of Kokkola. Thcy are foun d in t he E part of t he sheet, in Norrby, Ullava, Eskola , and in Rautio, bu t towards the coast the eskers becom e lower and they are buried under shore deposits. Th e to ps of the ridges, resembling shingle bars, form also here the core of sand pl ains. The course of eskers is usually fairly rectilinear, bu t someti mes the es kers wind like rivers, even t hough the winding does not influence t he main course of an esker. Very often t he flat tened plains join t he esker ri dges.These fla t for ms hecome more common to wards the sea coast. They may have been for med by t he wave erosi on, which flattened the esker when rosing from the sea and cut off its uppermost par t unt il the coarser grave l beds situate d deeper down were laid bare. These layers extend now to the surface and form gravel plains, which t hus lie in their primary position. Only few kettles are to be found and t hey are of small dimensions. As far as they have existed earlier , they have later become filled up with shore sand. Likewise , parallel es kers are rare. ST}tUC TU lm Fluvioglacial deposits consist of sorte d and strat ified material. Th is for ms alternate laycrs of sand and gravel. Th e layers lie either parallel or cross one another, while their inclination and compass direction alt ernate . Most us ually t he layers stoop in t he same direction as t he slopes do. The limits of the layers are mostly distinct (Fig. 22), but Fi,!!. 22. Gravel and sand layers in Eskola esker. Photn '9. Ok ko. 30 sometimes secondary changes are foun d in them (Fig. 2:l). BEsides this, also t he primary position of whole strat a may ha ve later been disturbed. T hey have got depressions and folds, wh e n blocks of icc buried in Iluvio glacial drift wast ed away. Fil!. 23. Defurrued contact between pant and sa nd layers in the esker uf Svkaraine n. Phot o Y. Okko. . . T he struct ure of drift depends upo n the assortment of deposits. Thus t he degree of assortme n t determines the distinctness of layers. Sometimes the distinct strat ificat ion is lacking and the same bed contains both sand and well rounded stones. The succession of ass orted layers is very varied. On t he surface there occur somet imes sand, sometimes gravel and pebbles and it is impossible to judge from the surface what grain sizes there are in the layers beneath the sur fa ce. The 10 meters deep exp osed section in E skola es ker indicates t hat long layers of even t hickness are rare. The thick layers are sharply edged between other layers and are to be fou nd again a little farther away. Stony beds are u sually sit uated in t he uppermost part of t he sections. At t he bottom there are assorted sand and gravel. Only in one diSCOVEry poi nt, in Sundby near the to wn of P iet arsa ari . does t he se ction go t hrough the whole Iluvioglacial strata. From under it a smooth, water-worn s urface of th e bedrock becomes bare at the depth of abo ut 2. 5 meters . The abrasion of water has been so unimportant that on the surfaee there have re mained weak glacial seratc hes coming from t he direction ;J20°. Certain layers have also int erior structure, e. g. the cobbles of stony layers have placed t he mselves Hatways either horizon tall y or parallel to t he bedd ing. In sandy layers there OCCUI'S cross bedding and in layers of sti ll finer fract ions the parallel structure predominates. T his kind of silt a nd clay has been mct with at t hree places inside fluvioglacial drift. T he undisturbed structure of these sediments indicates that they ha ve been deposited in the present localities and their microfossiles (Table I ) point to the late -Glacial brack ish wat er flor a, which is of the same type as in the drilt of Kokkola. Table 1. T he percentage of pollen particles (analyst: K . Salminen) and dia tom gronps (analyst: K . Molder) found in eskers. r'ouon Diatom s i i i per r-en t. per cent I Hei~h t I J) b ('f) \'t'r ~' T)c"t h X'J. Iluint Qu :lI i t~· of t he sedtnn- nt 111 m . in r ill (a l'l,r. ) ,• ~ 1~ lg )~ , I ;:: ~ j , ;: I~ " i E I ~ 1 i :!+ Sykdrdinen varved siltclay 120 2flO 2 4., 45 1 8 5 I , 1 194 1 ! :!.j • , 3001 I 3D 51 l U H 3 18D ' ~fj • 1 grayish day 360 I 14 75 0 15 3 \ 82 I blue clay 3Hu 1 2: 78 I :27 " I 10 72 1117 20 total amount , III Jylhii I st ratified sand and fine sand 60 110 i- 2 ll:! • plastic clay i,n piece, s 125 - 121 1 -10-1- -288i- 113 , " » 160 1 114 Jylhii J[ stratified sand GO GO 24' 172 4 I ' - 1 1 - I I 115 • varved fine sand and silt 80 - ~ , .!:! - , - 1I1i , gray ish eiltcluv 105 - -= - , 1 per cent 3 Eskula va rved ailtclay flu 3flO /- ; 5 1871 8 lO i 4 , 3GO I 118D • ,• 31 12 7G I U I oj • • 370 211 :77 111l 1 I U · • , I 330 I I 3 ;85 11 I i I RA'SGE S OF GRAIK SIZES T he loose cons truction of fluvioglacial dep osits is caused by the la ck of silt and clay. Whenever these grain sizes are found, t hey form t heir own layers, but mostly fln vi oglacial drift is quite free from t he m. Ordinary ridges, es kers, are commonly built up of coarser fractions such as stones and gravel, whereas flattened plains are sandy, especially on the ir s urfa ces. .Many exceptions have been met with in the coastal region, where fluvioglacial d ep osit for ms stony plains, which sca rsely rise ove r their surroundings. Fig. 24 sho ws some results of mechanical analyse s made of fluvioglacial material, They indica te tha t gravel and sa nd form the main p art of 32 .o:::.2:.-_--.:;;=..----.:1.0 2;:.:...0 ...;;:::...,;.:;~--4, 0 7.0 2:;0 ~m IOO"n d eposits, whereas fine sand and S t ill finer grain sizes have there a more un important share than they 80 , have in till. The degree of assort m ent and the prevailing grain si zes vary both locally and regio nally, and neither is the assort m ent complete. 20 Hlj'+-H-+--+-+-t----~ LITH OLOGIC CO) rPOSlTI OX St one counts made from flu 0 8::::_ _ -L_ 1.----L_l-_ .-J vioglacial deposits, some of whi ch Fj~. 2·1. Ranges of grain sizes in stratified dnft .l = Rauti jar vi, Lchtaja, 2 = Ohteen ar e presented in F ig. 20 (marked ka ngas Kannu s, 3 = Kallis, Kaarl ela, 4 = with underlined numbers) indicate Sykdrainen, Toholampi, [) = Rahko sen- harj u, Ullava, 6 = Sundby, Pietarsaari. that fluvioglacial drift does not lit hologically differ greatly fr om the till of its vicinity. Both reflect t he local bedrock, but t he amount of far travelled cobbles is perhaps greater in fluviog lacial deposits than it is in till. The mixing up has been so effective that the lit hologic composition of stratified drift is unvarying from t he surface to t he bottom. The stone cou nts made fr om Norrby esker show that drift ha d been carried to its present location from the longit udinal dire ct ion of the esker or in t his case from NW, where the bedr ock is composed of pegmatite granite (Fig. ~5) . The stones of this origin reach the maximum of their amount in Iluvioglacial drift already at the distance of 4 km, fro m the SE lim it 20 80z 60 .. - ., 60 . ,, --. ---- - 20 20 o o t --t-' ...... ---- .r- ...... --' - --;::""1"'< x x x x x x X t- .-.. 0-- '"I .....- __ --.J ---- . X l( x x 4: N ORRB Y -----I,' x .; x l( x -f ::; """"R-"-/...." ~...x x x F i ~ . 25. Share of pegmatite granite stones in 1'i urrlJy esker, Alaveteli . 33 of pegmatite. On the contrary again, in t he esker there could not be found the peridotite of Seisartrask, which is situated 2 km. NE of the esker. There was plenty of granite gneiss in the esker as far as the SE limit of the before-mentioned pcgmatite granite area. ORIG-IS The structure , the outwashing and the ass ort ment of strat ified drift as well as the roundedness of it s cobbles indicate that t hese deposits have been accumulated by melt-v..·ater streams. These atreams have , of course , been situated on the site of present eskers, consequently in many cases on the divides of present rivers an d even in some places (t he esker .Iolkan harj u in the Norrby chain and t he eskers in Eskola) on floors lying higher than the vicinity (Leiviska 1907). Only few esker chains have been deposited in depressions of the t errain, where flowing water ought to have streamed, had it been able to choose its course freely. However, it did not happen thus, as the eoursc of other eskers is independent of the relie f. At the place of t hese eskers in the ice sheet there were obviously radial creva sses or other fractures , in which melt water was collected. The lithologie composition of stratified drift indicates that the transport - and thus the flow of water - was directed from the centre towards the ice margin. Thc great sand ma sses of esker chains, which increase towards the Gulf of Bothnia, were then carried to their present places from the sea basin, where on the ground of the lithologic composi tion of till occurrences of sandstone are supposed to be situat ed. Fluvioglacial material was carried by melt water only short distances. The coarsest grain sizes, as stones, gravel, and sand, seem to have been deposited almost immediately after they were carried into the melt water stream. The work of flowing water was so restricted that it sorted t he drift again, washed the fine st grain sizes away, and wore the cobbles rounded. It follows that t he ice, when trying to fill up the crevasse where stream flowed, carried drift into t he stream. Melt water must have flowed in the basal part of the ice, for only there did it come into contact with the load. Till could not reach very high in the ice, beeause the topography of the floor was smoot h and the ground moraine now covering the bedrock is thin. It is, however , diffieult to think t hat melt water flowed in open crevasses, for in that case the water body in front of t he iee margin would have extended its arms into crevasses and prevented t he water flow already before the crevasses were sufficiently deep to reach into thc basal part o f the ice loaded with moraine. Furthermore, the fact that the crevasses remained open presupposes stagnant ice (F lint 1942). It see ms rather so that the crevasses were later closed, then forming tunnels 5 2355( 19 34 (Okko 1945), where water would have flowed under a week hydrostatic pressure. If the pressure, for some reason or other, diminished, the flow of water st opped . Then the mouth of the stream an d the lowest course of t he melt wa ter tunnel turned into a long b ay , where sedimentation to ok place more slowly. This makes it com prehens ible that in so me places clay occurs inside flu vioglacial deposits. Judging from microfossilss t his sediment has been deposited in brack ish water during the late-Glacial birch peri od . SH ORE FORMAT I ONS SH ORE D EPOSITS Shore dep osit s are of wide distributi on in t he map sheet of K okkola. There they comprise the main part of t h e light green coloured borders of t he esker chains , but furthermore sh ore deposits ve neer also ot her deposits. They extend from the presen t coast to t he highest tops of the area. Shore deposi t s are commonly t hin, on ly seldom does t heir thiekness go beyond one me te r . Thicker covers a re found both on t he sides of es ker chains and on t he inland facing slopes of hillocks. Sometimes the waves have t hro wn up cobble bars on t h e tops of hillocks. On the terrai n with t he flat or gently s loping surface the t hin mantle of shore dep osit s commonl y smooths away irregul arities of the bedrock an d thus lacks its own topographic forms . The smoo thed forms are ch aracterist ic of sand plain s bordering on esker chain s. Their surface commonly slopes gently away from t he flu vioglacial cen tre, but the plains also joi n together and for m wide fields, which follow es kers 'from the inl an d to t he coast . The shore bars , dunes, and fluviogla cial ridges make them uneven. The sandy shore bars, which are particularly common on the sides of eskers, are here pre valent. Their successive bars p arallelling with the ge neral trend of t he shore-line conti nue from t he presen t coast far in to the interior. The shore deposits accu mulated on the unev en subsurface are sharper t han the forms described above. ' They form either boulder rims or rampar ts, which are locate d on the tops as well on the slopes of hillocks. The shore deposit s consist of assor ted sediments , the layers of which slope to t he trend of the surface. Coarser deposits accumulated at water level or in shallo w wa ter cover finer sed iments deposited in deeper water. The structure of shore deposit s po ints to the con tinual regression of the sea-level. OT HEH S HORE :\I A RKS The ubrasion marks, such as outwa sh belts null wave-cut cliffs, are rare in the flat terrain of the K okkola map sheet. This is due to the 35 rapid uplift t hat has no t allowed wave erosion to d ire ct its influen ce for a long t ime to the same level. The anci ent shores are found to be situated at almost every altitu de, which indicates that t he s hore-line has re treated fairly evenly all over t he mapped area. The altitu de between 90- 100 meters is, however, abraded more intensively than commonly is the case , which points to the fact that t he shore-line stayed t here for a longer time. ORIGI'S The common occurrence of shore dep osits and the unifor m st ruct ure of dep osit s provide evidence that the sea-level ha s by degrees ret reated to the present position. Simultaneously dry land in creased at the cost of water. The same phenomenon is to b e perceived on the present coast, where land ri ses approximately 0,91 m , in a century (Witting 1943). The uplift was earlier still stronger (Brander 1934, Sauramo 1937). Owing to t he manner of regression of the shore -line t he shore marks are t he older, t he greater the altitude at whi ch they are situated. The same age order is shown by the diatom flora of s hore deposits. The flora indicate s that most shore deposit s are of marine origin . The salt or brackish water diatom flora is fou nd on the present coast as far as the altitude of the shore marks in E skola. The shore dep osits in the E part of E skola esker at the height of !l2-!l3 m. still contain brackish water dia toms (Campylodiscu8 clypeu8 and Diliioneis interrupta) , though the main flora is already composed of fresh water diatoms (ll1elosira arenaria, several E pithemia species and Eunotia Clevei) . Because the salt and brack ish wat er diatom, are lacking in the shore dep osits at the higher altitu des, t he a brade d belt at the height of !lO-I OO m . in E skola forms there t he upper most lim it of the Lit t orina Sea. The di a tom flora of t he above-describe d phases of the Bal t ic, ciz, the post Littorina and Li ttorina Sea, (Back man and Cleve E uler I!l22, I!l37) differs so greatly from t he diatom flora of the K okk ola drift and from t hat of the fluvioglacial dep osits th at they cannot be of the sa me phase. The strat igrap hy of the lat ter is of an entirely different kind, and it is certain that this flor a represents the stages of t he late-Gl acial Sea, preceding the Ancylus-Lake. \ VIN D DEPOSITS On t he open coasts of the K okkola map shee t sand dunes have acc um ula te d under the influence of strong sea winds.Dunes are found especially at Ykspihlaja, Lohtaja, and K ala jok i, where they are situated on sandy fields surrounding the esker chains. On t he coast region dunes ' arc still living a nd lack protecting vegetation wherea s in the inland the only dunes to be found are st at ionary, covere d with trees. On the present dune coast there is to be seen a certa in zonarity, so 36 that nearest to ,t he coast-line on th e shor e bar there are small pre-dunes , . behind t hese a wide deflation surface , which is followed by a belt of large migrating dunes (Fig. 26). The alt it udes of these dunes vary fro m . .- Fig. 26. .Migrating dune, Tuomipakka, Kalajoki. Photo V. Okko. 10 to 15 meters. The belt of migra ti ng dunes is several kilometers in length, and, being parallel with the trend of the shore-line, separates t he dune coast from the forest-growing or boggy inland . The belt has an uneven long profile, as there appear dnne hillocks protected by vege tation, mi gr a ting dunes, and furrows caused by erosion. The inclination of the stoss-side of a migrat ing dune is 2"_5° and that of t he lee-side 18"_ 28" (Mattila 1938). The slopes beco me gentler with increasing age. The sec tions made in dunes (Fig. 27) show that the dunes are composed Fig. 27. Cross-section of a stationary dune, west of Lohtaja church yard. Photo G. Brander. 37 bot h of parallel and of crossbedding layers. The parallel structure is to be found in the undermost part, covering shore deposits beneath the dune. In the uppermost part an irregular crossbedd ing structure predominates. This indicates that deflat ion , deposition , and the direction of wind s have varied greatly. Wind deposits are lithologically and mechanically assorte d. The following mechan ical analyses show that they chiefly contain fine sand: Grain atzes in mm , s ami lle l Depth D illCO"CI)t point In em. x o, I > 2 I 2-1 IH,'I 0t,; 1<0," 1 Pietaraaari, Filboda ...... 50 - 0.3 0,5 11,5 87,7 I 2 Lohtaja, Kirkkomaa ...... 150 - - - 15,5 84,5 3 , I Alaviirrct ...... •.. 30 - - 0.5 27,1 72,,1 4 Kalajoki, Tuomipakka ...... 30 - - 0,5 28,7 70,8 5 Lchta ja, Vongan pakka ...... 20 0 ,2 2,2 10,8 66,3 20,3 Strong winds have carried also coarse sand, even gravel into dunes , but these layers are thin and rare. Th e chief p art of wind deposits contains ligh t silicic minerals, quartz and feldspars, from which t he colour of sand is derived. Furthermore t he sand consists of small mica sheets, hornblende, ilmenite , and magnetite. Ilmenite and magnet it e form here the smallest and he aviest mineral grain s. Th ey have often enriched in certain layers, giving them a dark colour. Du ne sand contains ap proximately 60 per cent quartz, 23 per cent feldspars, and 8 pel' ccnt micas (Rosberg 1895). The locat ion of dunes in connection with esker cha ins ind icates that the wind deposits are of fluvioglacial origin (Leiviska 1005, 1907 b). In the coastal zone there has occurre d enrichment of sea sand (Leiviska 1007) and flu vial sand (Rosberg 1895), but their share in t he origiu of wind deposits is unimportant. Th e growth of a dune depends both upon the velocity of wind and upon thc grain size of sand.According to Mat tila 's observations (1038) the wind blowing 5,5 m .jsec. at t he height of 2 meters move s sand along the surface, but when the win d blows more strongly it lifts sand to the height of 3-3, 5 meters. The wind depo sits arc accumulated even th en on t he lee-sides of migrat ing dunes, for according to Brander's observa tions sand is lacking in peat deposits behind th e dunes. Sand flies best, ,\~ h e n ice crust covering mineral grains reduces their vo lume weight. The rate of migra ting dunes varies between 0,5-1,9 m. per year (Mattila. 1938), but du nes are on the whole of brief dur ation. Veget ation begins to fasten their surface already in the coasta l zone and the travels of migrating dunes Illay be only a few hundreds of meters. 38 SILT AND CLAY DEPOSITS DISTRIB1JTI01\ Silt and clay together form sediments , which fill up depressions and river valleys. They seldom extend to the surface, being covered with shore and alluvial deposits and peat bogs. The widest occurrences of these sediments are found in river valle ys, whereas in t he SW part of t he area silt an d clay deposits are entirely lacking. For instance in the 4-5 m. high cliff of the river Uusikaariepyy there is found only sand on t ill. In the ground moraine areas the thickness of clay rarely goes beyond one meter. In river valleys the sediment bed is much thicker, in that of the river Lest ijoki somet imes over 15 m., but its average thickness is even here approximately 4-5 m. ORIGIN AXD QUA L IT \- The oldest clay and silt sediment, g I a cia I e I a y, was deposited at the bottom of the water body in front of t he ice margin . Glacial clay is a light grey or faintly reddish, varved sediment. Each varve consists of two laminae, the light summer part containing fine sand and silt and the darker grey wint er part being ric h in clay. The undermost varves deposited nearest t o the ice margin 'are coarser and t hicker than other varves. Glacial clay commonly lies on glacial drift and forms the basal part of t he sediment bed. It is exposed only on the slopes of river valleys, where the Ioosesediments have been wa shed away from its surface. On the borders of eskers glacial clay is embedded under beach sand. P a s t - G I a c ia I e I a y covering glacial clay is comp osed of t he finest grain sizes , which flowing water and sea waves have washed from deposits of earlier date . In the area are t wo kind s of post- Glacial clay, the older, Ancylus Lake clay, and the younger , Litiorina Sea clay. On t he Littorina Sea clay there rests without limit the sediment of th e present Gulf of Bothnia, otherwi se called post-Littorina Sea clay. All these post Glacial clays are more weakly stra tified a nd contain more organi c matter t han glacial clays do and furthermore t hey are often dyed black by ferri c sulphide. When t his clay becomes dry t he colour turns light grey. Then the clay also shrinks and becomes cracked. The walls of the cracks turn a brown colour. Frost breaks the uppermost layer of this clay into angular grains. The differen t kind s of post -Glacial clay can be best distinguished on t he ground of microflora. Such investigat ions were made by Brander in the valley of t he river Lestijoki. Brandel' present s th e following summary of the stratigraphy of silt and clay deposits (Fig. 28): 39 :z :z . [Himanka) 1. On the moraine , consequ ently undermost in the sedi ment bed, there is a thin layer of var ved, reddish grey glacial clay; Hilli /a 2 Luhtio 2. This clay is covered with Ancylus Lake clay, the thickness of which diminishes from the Pitk§sensuvanto inland to the coast; 3. The basal part of Ancylu s Lake clay contains almost regu Tokola larly a few salt water diatoms in the fresh water plankton flora. J unka/a The thickness of this layer increa ses towards the coast; 4. The topmost part of Ancylus Lake clay is deposited in fresh «onnos water, which has gradually become shallower, as it contains a great nu mber of epiphytes and bottom diatoms. This layer becomes thin Ta/ni o ner towards the coast; POlviko.ski 5. The Littorina Sea sediments covering Ancylus Lake clay reach as far as the height of about 93 meters; 6. Littorina Sea clay is deposi ted between 93-45 meters in brackish water ; 7. From the altitude of 45 • meters to the present sea-level • the brackish water sedi ments are covered wi th salt wa ter clay. Toho/ampirar Starting from the height of 30 met ers it forms the chief part of N the sediment bed ; 8. On post-Glacial clay there is almost always a mantle of alluvial sand. It somet imes con tains salt water diatoms and Ah ola sometimes fre sh water such. ALLUVIAL D EPOSIT S SykiirMne/J Alluvial deposits here include I all sediment s accumulated by the <5 V> o rn 3 40 activity of running wa ter. A p ar t of these deposit s has drifted t o the mouths of rivers, where it has been accu mula te d into deltas or has come u nder the influence of t he surge. A second part has been dep osited alread y in t he standing waters of rive r s or has spread as alluviu m on t heir flood pl ains. For this reason alluvial dep osits for m narrow occurrences along the ri vers. On the _coast the alluvial area becomes wider, which is par tly due to the fact that the alluvium has no t yet p aludificated, partly t o the fact that o wing t o t he retarded uplift t he a mo unt of alluvi al deposits h as increased. Alluvial dep osits contain all t he matters that rivers have transported: stones, gravel, sand, silt , organic rerna.in s, and humus solutions. The current has assorted t hem , even though the spring flood and breaking up of t he ice disturb sedimen tation. Sand and fine sand form the most common grain sizes in the alluv ial deposits but the humus content is there more important t han in shore and win d dep osits. CHEM ICA L SE DI l\t E~TS When ground water emerges to the surface as springs on the bor ders of sa nd areas or joins t he water of la kes and rivers, precipitati on of dissolved mat ters from the water takes pl ace.In t he mapped area a few unimportant occurrences of siderite and vivianite have been found. In p eat bogs they form thin lenses, which contain both siderit e and vivianite in varying combinations. Vivianite forms also smal l knolls in postgla cial clays, and it has bee n ascer tained around anima l bones, buried in the Li ttorin a Sea clay (Salmi 1948). P recipitation of iron hydroxide is fairly common and the occurrences of bog iron ore are numerous , but of no practical importance. S HELL DEP OSITS Shell deposits in F inland concentrate themselves on the SW coas t of Finland , wh en ce they exten d along t he coast of the Gulf of Bothnia as far as the K okkola map sheet . Only three small occurrences (Tigers tedt 1887), which contain shells of Mytil'l18 edulis have been found.T hese shells arc present also in Littorina Sea clay. SUBSURFACE W ATER R ain water entering the ground (p recipitat ion .';00 mill . per year) gathers on the bedrock and in its fractures as ground water . Entering downwards in pe rmeable deposits, water dissolves minerals and becomes hard. The wa ter table lies on the divides higher than it does in river valleys and it lies higher in the inland than on t he coast. Wh en flo wing slowly towards rivers and the sea subsurface wa ter is divided int o separate p arts. One p art e merges as springs on the border of sand and clay areas, t he se cond p art flows along alluvial and shore dep osits covering clay, and t he t hird par t is pre ssed into porous layers under clay and gets there under hydrost ati c pressure. Owing to this division the surficial deposits of river valleys and plain lands give less grou nd water t han elsewhere, where t here is a suffieiency of it . In the river valley s ground water has been conducte d from t he spring s on the border of moraine terrain and flood plai n. SOIL PROFILE Rain water, which permeates through debris on the surface, is able to dissolve iron, alu minium , calcium, phosphor and other substances fro m certai n minerals. Owing to t his , the la yer under debri s becomes whiter. A p art of the di ssolved substunces, especially in the case of iron and alu miniu m, precipitates again, forming a rusty brown enrichment layer, Bihorizon. I n the sandy dep osits the soil profile is most visible and sometimes t he enrichment layer for ms t here a hard crt-layer . On t hc whole, the soil horizons become more discernible on the inerease of t he absolute height and consequently with increasing geologic agc, but, depending on the quality of debris a nd on the mech anical composition of t he minaral depo sit under it, they vary on surfaces of the same age. PEAT DEPOSIT S DISTRIBUTI05 The relatively ri ch precipitat ion, t he flat top ography, a nd the impenetrable floor have brought abou t the for mation of bogs. I n the map sheet the share of bogs comprises 43,5 per cent of t he land area (Back man 1919). Most bogs are situated in the hill y landscape of Su ornen sclka (F ig . 29). According to Valovirta, t he chief part of the bogs belongs to t he Nort h-Finnish soligenic bog complex type, where the wat er y Carex whit e moors predo minate. The South -Finnish ombrogeni c Sphagnltm [uscu an rai sed bogs are found in the SW part of t he area. Peat bogs gro wing birch and spruce occur mostly along rivers and little strea ms and on t he sea coast, where t he development of bogs has star ted only in present times. Eutrophic brown moors are rare. 6 '!. 355/ -19 42 M ' ,. 10 lj 2Qkm RAAM < 30 % 3 0 'd) ~ 40 SO PyIJij/o + 50 60 60 70 > 70 Fig. 29. Geographical division of landscape, abundance of peat deposits, and distribution of investigated bog areas. 1. River landscape of Oetrobcthnia, II. Hilly landscape of Suomenselka. III. Plain landscape of South Ostrobothnia. • = peat bogs containing mainly Carex-peats. o = peat bogs containing mainly Sphagnum-peats. P EAT T YP ES Inventory investigations of peat supplies have hitherto been carried out on 20 peat bogs (Fig. 29). On the base of these Salmi has calculated the frequency of peat kinds as follows.. 43 Sphagnum peat . 25,9 per cent Eri ophorum-Sphagnum peat . 13,9 » » Scheu chzeri a-Sphagnum peat . 0,9 » » Carex-Sphagnum peat . 13, 1 ,) » Carex peat . 11,4 ,) ,) Sphagnnm-Car ex peat . 28,8 » » Ligniferous peat . 5 , 5 ,) ,) Bryales peat . 0,5 " " The relations of peat kinds in different bogs differ considerably from the averages. Salmi has observed that the Sphagnum peats predominate in the granite and quartzite areas and the Carex peats in the biotite gneiss areas. According to Salmi it may due to the fa ct that the iron and potash content of t he latter rocks has furt-hered the forming of Carex peats. The peat stratum in the bogs of t he mapped area is rather thin , about 50 per cent of t he bogs being less than 0, 5 rn , in depth. The peat strat um is thinnest in the coastal region, whereas in the interior, where the bogs are older, peat bogs 4-5 m . deep are found. The average thickness of pe at may be about 1,5 m. STRUCTURE AND D E VBLO PMEh~ OF BOGS The forming process and the later development of peat bog s is reflected in their stratigraphy . The bogs of the mapped area are chiefly co mposed of terrestric and sernite rrestrie kinds of peat, which usually lie on mineral ground. About 95 per cent of peat deposit s in Middle Ostro bothnia are formed through t he paludificat ion of forest land (Backman 1919). In some places at the bottom of peat strata there are also found limnist ie sediments, mud and ooze, whi ch show that the bog has primarily begun it s develop ment wit h t he filling up of shallow water basins. Their pal udification has commonly started already at sea-level, for the Jimnisti c sediment s contain salt water diato ms and remain s of littoral plant s close beneath t he peat strat a. Also nowadays the paludification starts eit her with t he filling-up of shallow oozy bays of t he sea, or , as ofte ner see ms to be the case, with the over-growth of lagoons. The small ponds be t ween sandy bars as well as the ends of bays turn into Carex- and Egllisetum-growing swamps , whi ch later on change into treegrowing Sphagnum dwarf shru b peat bogs. Thus the peat stratum becomes thicker, and the bog spreads, making the surrounding forest land swampy. Its veget ation depends upon the lithologic composition of the ground and upon water relations. Different kinds of palu difieation join so closely together th at t he wide peat bog com plexes always contain areas of different origin. 44 DEVELOPMENT OF FLORA AND C LDIATE By exammmg macroscopical remains of plants and pollen particles buried in the course of time in peat layers, it is possible to establi sh the ancient flora, which has for med a peat str atum during the various phases of the development of a peat bog. This development is t o be seen in the profiles and in the pollen diagram s (Figs. 30 and 31), where t he rf 2J.,m Hf S 10 0 / 0 2 0 .JO ~ SO 60 70 80 m 1 1...:----1 o.s 2 3 ITIIIIIIIIIllJ 1.0 " 5 1 3 j\i ~ j f.s 6 ~ 2 .0 7 ! it? 1 8 1\>:: :1z.s ffi~• ~.:.."O'.:.. •_.:....,..:.."-~~ 9 :..(.:r ."":;'... '-:- ::""" fa t"~"c-o-o-c""-~i o 3 .0 f 1 t l ': '".;'?;.}) 2 c=J .J C=:J 4 ~ .; ~ Fig. 30. Profile and pollen diagram of the bog Hongiatonneva at Toholampi. Curve on left sh ows huminosity of peat. Sig ns used in profiles: 1 = Sphagnum peat, 2 = Eriophorum peat, 3 = Carex peat, 4 = Bryales peat, 5 = Equisetum peat, 6 = coarse detritus ooze. 7 = fine detritus ooze, 8 = sand, 9 = silt , 10 = clay, 11 = clay ooze. Signs in pollen diagrams: 1 = Picea, 2 = Pinus, 3 = Betula, -1 = Alnus, 5 = rare deciduous trees: Tilia with black, C = Corylus, U = Ulmus, Q = Quercus , Da = Carpinus. regularity of the pollen lobes of t he different species of trees are indicators of climatic condition s. The pollen diagram s examined in the mapped area can be divided into three pollen horizons, viz., the uppermost horizon or the post-Littorina, the Littorina horizon underlying this, and the Ancylus horizon , of which t he last-mentioned forms the first post Gla cial st age. In t he map sheet the late-Glacial epoch is visible only in Iimnistic sedi ments. The pollen flora in different horizons has the same 45 main features, whi ch are characteristic of these horizons else where in F inl and (e. g. H yyppa 1937). The microflora of the late-Glacial sediments favours t he hirch and shows that a warm climatic peri od thcn prevailed in the area, hecause, in spite of the nearness of t he ice margin also some pollen p articles of rare deciduous trees (ct. p. 27) had fallen t o the bottom of the water body. T he share of conifer pollen was t hen insignificant. IS.*$m H I .J to 0 70 8 0 "" os () <:: " '-. 1.0 ~ " 9' <," 9' /.S "() c' C\. c. 9 ' 2 . 9' CfUt 9 ' CJ U' 9 Z. CZ ~l. c» ~ , //2.93 t> U 2.92. c:: C, (Jui' l. " 3 . U Z.? 2 t.. ceo , ..I2 " c roro r -.....J 3 CIUr c ,u ~ ,.....""','... u , c, q , u> " o.J...L"""'=£tL:~d~=I-_.....J__--'--""'_ Fig. 31. Profile and pollcu diagram of the bog .Iatkonevn at I\: ulviii. In the An cylus period t he pollen lobe of pinc becomes stronger and pollen of rare decidu ous trees as well as pollen of alder are rarc . The pollen lobes of deciduous trees incre ase at the beginning of the Littorina. During thi s period alder and rare deciduous tree s attain their maximu m. At the end of t he Li t t orina , spruce , which has a narrow pollen lobe , in creases and reac hes it s culmination in the post-Littorina. Simultaneously, or a lit tle later , the po llen lobe of rare deciduous trees breaks off and other de ciduous trees be come less common. Such developmen t of forests, as reflecte d in t he pollen diagrams presented above, shows t hat at the 46 end of the late-Glacial epoch the clim atic conditions have been fa vour able, perhap s corresponding to those of the pre sent day. In the Ancylus period t he climate became continenta l, pine-f av ouring, and at t he end of the same period it again turned hu mid and warmer than before . During the post-Lit torina the climate becomes cooler towards the present time . The macroscopic remains of plants , imbedded in the ooze under peat stra ta, indicate a similar development of the climate. According to Valo virta's examinations these remains show that the main part of the present flora was already growing on th e shores of the Ancylu s Lake. Also Naia» flexilis grew there (Backman 1935), but it died out from the area at the end of t he Ancylus period. On the Lit torina Sea coast A lnus glutinosa was more common t han Alnu s incana ; the relation was thus opposite to the present conditions . The opti mum of the climate permitted the spreading to th e mapped area of exacting plants, such as Ca.rex IJseudocyperus, Ceratophyllu m demersurn, C. submereum, Lycopus eUl'Opa eUB , Najus marina , R1tl)p'ia ma ritima, R . spirali«, Zannichellia repens, and Z. pedicellata. During the post-Li ttorina t hese plants, which are regarded as ind icators of a favourable climate, begin to become extinct. F irst Cerato IJh yUm" submersuni die out, then Rup pia spiralis , and Carex pseudo cy pe r'l18, whereas Ceratophyllum demers um, Carex diandra , Naja» ma rina , and Ruqrpia mariti ma , which were co mmon in the Lit torina period , become rare. PLEISTOCENE DEVELOPMENT MOYEMENT AXD :MELTING OF THE I CE SHEET The traces of glacial erosion (Fig . 6) show that t he movement of the ice flow took place from t hree different directions. These are (in order of age): I movement direction from 285°-300° (in azimuth s) II , » » 325°-340° »» III , » » 345°_ 360° » » The cen tre of the ice sheet evidentl y cha nged its place from the \Y side of the map sheet to its NWN side (Helaakoski 1n43, Ljungner 1945 , HYYPF ii 1n48). Th e I and II stages of the movem ent abra ded strongly t he bed rock and caused stoss-and-Iee topography. During the t hird movement stagc th e glacier glided over the area very ligh tly and eroded only the projecting kn obs of rocks. The traces of the first and second s tage originate fro m the most effect ive activity of the glacier , .whereas the traces of the third stage may have been caused by the last movement of the shrinking ice. The thin load of glacial drift was carried by the basal ice during the I and II movement stage, although even then the ave rage transport distance was rather short. The main part of t he moraine was accumulate d su bglacially and now forms ground moraine cover on t he bedrock. Th e uppermost part of the ice, which contained less till, may have still conti nued moving an d have smoothed t he subglacial mora ine topog raphy. After t he II move ment stage the ice sheet covering t he mapped area began to melt. Th is happened by t hinning during a long time, because t he area is situated near the centre of the ice sheet. Melt water Illay have partly evaporated, partly it has collected in the crevasses, which were parallel with t he second movem en t direction . There the melt waters pushed their way in to the basal part of the ice containing moraine, from where running water assorted and washed glacial drift at the bottom of its bed and accumulat ed it. Deposition took mainly place sub glacially, for till and st rat ified drift do not differ lithologically from each other . Only the fine grain sizes, sand, silt , and clay, were transported to the terminus of the glacier , where they have been deposited as varved sediments in deep water . Between the second and third movement stage t he ice margi n retreated over th e mapped area. From this melting stage the drift of 48 Kokkola, in dis tinct end moraines (Le.i'viska 190i), and possibly the strat ified deposits of the N part, situ a t ing beneath a t ill-like mantle, deriv e th eir origin. This mantIc , as well as the breccia moraine of Frost and of Leppalahti, and the stony moraine in Forsby on the fine sand sediment were for med during t he last oscillation or, the third movemen t stage . As the margin of the ice then e nded in a water body over 200 meters deep (Sauramo 1938), it is possible t hat the icc, after getting free fr om the basal load, was bu oyed up to a floating position controlled by the water level. The smooth erosio n of the third movement would be explained by the uplift of the water. With the melting period t here is temporally connected a discovery of ma mmot h remains, whi ch was made at A laviirret in the parish of Lohtaj a, The discovery consists of two well p r eserved pieces of ab out iO em. long th igh bones (determined by V . 111. Klemola , Ph.D.) . These bones (Fig. 32) were buried in glacial siltclay at the pre sent shore lin e near the mouth of t he riv er Viirretjoki (found by farmer -Iuho Rautava in 1924 and about in 1930), where they had dropped out eit her from the ice edge or from a floating iceberg . CHA"KGING Ol<~ TH E SHORE- LINE According to the microflora, found in the drift of Kokkola, in esker clays in Eskola, J ylha and Sykarainen , a s well in ot her glacial sediments every where in the .mapped area, the melting of the ice took place at the Fil!. 32. One' of th e mammoth thigh bones compared to that of elephant . (l ~ usi Suomi 1936). 49 end of the late-Glaci al epoch, when the climate was compa rat ively mild and birch-favouring, whereas the water in front of t he ice was cold and brackish . This sea covered the whole area , as its shore-line is situated at least 200 m. higher than t he present sea -level (Bra nder 1934, Sau ramo 1938) . The in vestigat ion concerning varved sedi ments (Sau ra mo 1928) shows t ha t the area was freed from ice between the years 1l00-1300 after the Second Salpau sselka stage or 500-300 years before the end of the late Glaci al epoch, During the first post-Glacial period, the Ancylus Lake st age, the highest hills of t he area were laid bare, and after that the exten t of emerged land increased rap idl y un der t he influence of lan d upheaval. Before t he cnd of t he Ancylus t he area above the average altitude of 100 meters rose from water. The first traces of water turning brackish again or of the beginning of t he Lit torina Sea stage appear, according to the invest iga tions of Backm an (Backman an d Clove -Euler 1922, Backman 1935, Backman and Clevc-E uler 1937) and Brander (Okko 1949), in t he E part of t he p ari sh of P yhajoki (the Hetetl ampi- area ) at t he altitude of 107 m , ab ove sea-level, while in the parish of Sievi (the Ristila-area ) they appear at t he height of 104 meters. The main indicator diatom of t he Lit torina Sea , Cam pylodisc1ts clype1ts, was fou nd fir st in post-Glacial clay at Toholarupi church at the height of 92 meters, in Sievi 100 ,5 meters, and in Pyh ajoki 101 , 1 meters above sea-level. The in crease of heights to the NW depends on the t ilting of ancient shore -lines. At the beginning of the Littorin a Sea stage, about 5 000 yea rs B. C., t he retreat of t he shore-line was ret arded and then t he existing coastal zone was washed more strongly t han earlier. Since then the rate of regression has constantly diminished . When t he shore-line passed the average altitude of 50 mete rs, spruce began to be common, and the shore-line was lying at t he height of 40 meters, when t his trce attained its first post-Glacial maximum, which marks the end of the Littorina peri od. The coastal zone, lying bencat h the altitude of 40 meters, was laid bare du ring t he pos t- Littorina period. The retreat of t he shore-line is clea rly seen on t he present coas t , where t he uplift was approximately 9, 1 mm . per year in t he yc ars 1898-1927 (Witting 1943). Simultaneously with the land upheaval there occur s also coas tal and fluvial dep osition , under the influen ce of whi ch t he alluviums of rivers and the basins of bays , connected by narrow sounds with t he sea , turn into dry land faster than do the open coas ts. The increase of dry land is especially fast on t he sheltered coast of Kruununkyla , where 7,2 hectares of new land grow annua lly fro m the sea (Brander 1934 ). So considerable an in crease of t he land area, depend s to a grea t exte nt, upon alluvial depo sition , which here takes place at t he bottom of a low basin, almost entirely isolated from t he sea. 7 2355/.(9 50 On the open coas ts t hose islands and headl ands gro w fastest, on t he shores of which waves an d coastal currents contin ua lly drive up sand . Under t he influen ce of the above-mentioned action t he shore-line is continually t urn ing towards t he sea and t h e face of the landscape changes rapidly _ DEVE LOP ) IENT OF E MERGED LAND Land rising a bove the sea-level becomes gradually dry a nd ycgetation in vades its surfaee. Sandy flatlands begin first to grow alder a nd willow shru bs, while small lakes between sand bars, as well as shallow oozy bays are filled u p and begin to paludifi cate . Only the sand dunes on the open coast s are bare , but before long E lsp n u«, Empetrusn, and Callusui get a foo thold on t heir surfa ce and little by little t he wind deposits are covered by pine forest s. Simult aneously the water table sinks and water running along the surface see ks it s way to rivulets and rivers, which discharge into t he Gulf of Bothnia . When flowi ng over the plain sediment fillings in old valleys t he ri vers overflow their banks in spring and spread alluvia l deposits over the su bmerged plain. Thus the thickness of alluvi um increases year after year. On t he uppermost part of surficial deposits, which is lying ab ove t he water table, t he soil profile is forming everywhere, for rain wat er leaches certain substances away from the whiterring A-horizon, carrying them to the B-horizon, which turn s brown. Some of t he dissolved matters are transporte d into ground wate r and t hey d o not precipitate uu't il gro und water ag ain co mes forth . The swa mps are turning in to peat bogs a nd when their peat strat u m grows in t hick ness, the bogs will sprea d to forest lands. Their area is thus on th e increase. P REHISTORIC SETTLEMENT AND THE R ETRE AT ING SHORE-LINE The prehistoric settlement has follo wed on t he heels of the retreat ing sea. The oldest dwelling-places of Ston e Age man are situate d on the area, whi ch was laid bare at the en d of the Ancylus period, even though t he main Stone Age set tlements are found in a zone risen from the Lit.torina Sea .H ere the younger the s tages are t he more below t he highest Littorina Sea coast line are the various styles of Stone Age implements a nd objects situated . During the t ypical comb ceramic pottery cult ure the shore-line lay a t t he altit ude of 6\ meters , du ring t he boatsliaped shaft-hole axe culture 51 at .53 meters, and at the end of t he cord ceramic pottery cult ure at 40 -43 meters above sea-level. At the end of the Sto ne Age the shore- line was about 40 m, higher than at p resent , as Stone Age dwelling-places have not been found beneath that line and as the cord ceramic pottery culture is ever ywhere in F inland the youngest culture stage of the Stone Age. The settlement see ms to have followed also th e retreating post Lit.torina Sea coas t, even t houg h discoveries are few. In t he vicinity of th e shore-line , howe ver, several burial-places or cairns have been found. Some of these con tain objects originating from the Bronze a nd Iron Age cultures. Judging fro m t heir height s these cai rns lie in the area laid bare 1500-3000 years ago . The fis hin g-place in Alaveteli is considered to be a lit tle younger, originating from about 500 A. C. (Backman 1936). The continuance of t he same method of fishing until the 1i th cent ury is to be regarde d as a mark of the antiquity of t he presen t set tlemen t, t o which also some names of localities point. CI VI LIZAT ION AND SURFICIAL DEPOSITS INFLUE X CE OF DEPOSITS ox THE PRESENT SETTLEMENT T he distribution of surficial deposits has almost decisively determined the location of the present settlement . It no longer follows so much t he sea coas t , but has been concentrated upon more fertile deposits, viz. upon alluvia l an d clayey plains of river valleys and coastal lowlands, offeri ng the best possibilities for agric ulture, whi ch forms the chief means of livelihood of t he present popul ation. Also the drift of K okkola has been early cultivated, even though its surface is in many places very sto ny , and t he settlement is there dense. The b oggy ground morai ne areas between livers have remained sparsely se ttled, wooded regions, which the net of roads has avoided up to recent times. The set tlemen t is thin on sandy esker chains, too , although many roads originating fro m ancient times follow them from the interior to the sea coast. TECHN ICAL USEOF DEPOSITS In connection with the revision of the map sheet attent ion was also paid to the t echnical use of deposits. The occurrences of deposits suitable for t echnical uses are to be see n in Fig. 33. The es kers and the loose outwas hed surfaces of ground moraines contain gravel suitable for highways, and it is taken thence for local use. In the map shee t there are only t wo noteworthy occurren ces (Nos 1 and 38 in F ig.:13), Lapaluot o, south of the town of Raahe, and the E skola esker, which provide gr -avel also for t he State Railways. 52 .< 2' " , ''' gral'''' for railways, mora ine dcpo e it RAA"" 2 .. grm' el f or roads, 3 Iil !l r k k clay, •• g ru t'el [or railways, {ludogl . .s • g ra rel fo r roads , and s hore deposit 6 .. gra.to/·f {o r CQ1IN"c te, 7 CD sa-nd f or l"O of i n~q t ile», " " • e -sa·n d tor -mlUIQll.r y , " 9 0 Quartz 8untl " ' 0 • sand f or thinn ing of cray " 0 bri ck clay .e '0 " + S iderite 1IJi.. .l~ . 1.1 •• ",. X V irimu1c 1<'010./010 + . F uel peats e" 4 20 so Toholampi!. 1 52- u "ava 4 5 0 ~55 e" " Fig. 33. Occurrences of surficial deposits suitable for technical uses. The eskers and shore deposits con tain gravel and sand suitable for various building purposes, though the too great humus content of the lat ter has a detrimental effect as regards t he making of concre te . The well asso rte d wind deposits are too finegrained (see p . 37) for uee in t he building industry and t he hug e quantities of fine sand in dunes have not yet found a technical use. Quart z sand, which con ta ins 0 , 2 5 per cent FC20 3, has been fou nd onl y in one unimportant occurrence near La ke Ullavanjarvi, 53 There are in the area a few occurrences of useful brick clay . The best qualities of clay for brickyards are obtained from varved se di ments, which seldom reach to the su rface. Besides these , raw material for local brick-works is taken fro m t he sulphide- bearing Lit to ri na and post Littorina Spa sediments. The wid e bog areas of t he in terior contai n large quantiti cs of peat suit ablc for fu el, bu t ac cording to t he in vestigations made hitherto, t he productive peat strata arc too thin for the production of fuel peat on a large scale. Instead of t his the mo st decayed peat can be vcry well used fo r do mestic fue l. T he possibili ties of ge t t ing moss litte r are also limite d , for in t he bogs of t he area t here is only a thin cover of raw Sphagnum peat. It can, however, everywhere satisfy local needs. LIT ERATURE AH L:\IA 'S~. H . \V:SO"N , 1938. tiber dRS Entsteh en von Tot eis. Geol, F oren . For-h. Bll. uo, BA<:K )I A ~, A. L., 1919, T orv rna r ksun d er sokn inga r i m ellerst a Ost er botten . Acta Ior estalia fennic a 12. - +- und ASTRID CLEVE-EULER. 1922 , Die Fo saila Diat om eenfl or a in Ost er botten. Act a forestaHa Iennica 22. -'1)-. 1935, Borich tigung zur Clyp eusgr enze in S ima und Ka rsama ki. Soc. Scient. Fennica. Co mm . B iologica e V. 2. - -) -. 1935, D ie n ocdlichst en Fossilfund c von Naja s Ilexilis und Carex pseud o cyper us in Finnla nd. Soc . Sc ient. F erm ica . Com m . Biologicee V. 3. - ')-. 1936, S m ittesmossen , en forhi storiak fiskep la t s i m ellers ta Osterb ot t en. P en n ia 61, N:o 4. _ - oc h e LF-VB·E u LER . A STRID, 1937, Om Litorlnagransen i H aapa .vesi oeh d iat om acefl oi-an pa Su omcn eelk u. A ct a Soc. p ro Fauna et F lora F enn ica 6. - 1/-. 1943. Cer at op h y llu m sub m ersu m in N or cleuropa wahrcn d d el' Post .gla aia l ze -i t.. Acta So c. p r o F au n a et F lora F ennicu 3l. B ESKO\\', G.. 1935. Prakt.isk a oe h kvart .arge o logisk a r ceultat uv gruein vent.cr ing i No rrbott ens Inn. Summ a ry in Geol . Foron . P or h . Bd. 57. BRA :'HHm. G. , 1934 , The Gen ere.l Geolog ical Map of Finland. Sheet C 3 Kucpio. E xplanation to the m ap of su rfic ia l d e posits (in Finnish). Geological Su r vey nf Finla nd. - ,)- t . 1943, Neue B eitruge zur K cn n tnis del' inter glazia len Bildun gen in Finn la n d . Bull . Comm. geol. F in!. N :o 12 8. Eaen s, ED ITH, 193 7, Zur Ent st eh ung d el' D ru mlin s a ls St.romlinienkorper; Zehn weiter e J ah r o D r u m Iin forsch u ng (1926 - 1936). Neues .I ahr b . f . Min ., Oeol. uno P al., B d. 78, A b t . B . F LD"T. R . F .• 1942, Glaci er Thinning during D eglaciation: pt . II. Glacier Thin nin g inferred from geologic D a ta . Am. J o u r . Sci., vol . 53. -~-, 1947, Glacial Geology and t h o Pleis t ocen e Epoch. J ohn Wiley & Son s. I nc. New Y ork , U . S. A. G R..\ ~u. •r. C ., 1031. D ie geogr-aph isch en G ebiete Pinnla nds. Publ, l ost. Geogr . Urriv . Ab oen sis N: o 6. H A U!~ E S . H., 1944. D ie Ba n k u ng a ls r egio n nl e Ob erf'lachenerschein ung im pra kambr-isch en F el sgr-u nd d es Sch a r-enh ofes im stulwest .lichen Einnlan d . F erm in 68. X :o 3. H F.LAAKOSKI, A . R ., 1943, :\l a nn erjaiit ik on Iiikuntosuunnista, Poh janm aalla jn Tumpereen ympar-ietossa. F cnn ia 67 . N :o 1. HOLlIES. CHAUNCEY D .• 1941. Till fabric; Bull. Geol. Soc . of A m . Vol. 52. H v vr-r -x. ESA, 1937. P ost -Glacial Changes o f Shore-Line in South Finla n d . Bull. Co m m . geol, F inI. N :o 119. _ - . 1946 , Origin of eskers. L ect u re b efo re the Geol. Soc . of F inlan d . -~ - '- . 1948. T ra cin g of Source of the P yrit e -St on es from Vih ant .i un t h e Basis of Glacia l Geology .Bu ll . Comm. gc ol. F'in l. N:o 142. K IVEKAs . E . K .• 1946, Zur K cn nt .nis d el' m echani sch en chcmisc h cn und m incralo rrischcn Zu sammensetzung d el' F'inniach cn :\[orfinen. Act a run-alia fenniea 60, 2. 55 L AITAKARI, AARlS"E . 1937, Annual R ep ort of the Activities of the Geologinen T oi mi kunta (t he Geologica l Survey of Finl and) for t h o year end ing D ecemb er 31st, L936. H elsinki. L EIVISKA. I., 1905. -a ber d ie K tist enbildungen d es Bot t .niachen Meee busens zwisc h en Tornio und K ok kola . Fennia 23. ~ : o l. _~_. 1907, U ber d io Oberflach cnbildungen Mitt.el-Ostb ot t.niena und ih r e Ent st eh u ng. F ennia 25. N :o 2. _ .)_, 190 7 b . D ber d ie E n teteh ung der- Dtln engobict e a ll d er Kttst .c d es B OH ni sch en Meerbuaena. F ennia 23. N :o 2. L .1 U ~G ~ER , ERIK, 1932. Spalt entekton ik u n d Morphologic d er Sc hw ed isc h en Skage rrak- K uetc. T ell III: L icfer ung 1. Bull. of the Gool. I nst it. of U psala . vet. XXI. ____ • 1945, Den sista nordiska ned isningens for-lopp (Verlauf der let zt en nor d ischen Vereisung}. Geol. F oren . F or-h. Bd. 67. L UN DQ VI ST , G., 1940, Bergslagene minerogen a jordarter. Sv. geol, u nders, See. c, N :o 43 3. _)_. 194 3, Norrfarul s jordarter. Sv. geol. unders. Ser . C, N :o 457. _ .)_. 1948, Bloc kene orient .er -ing i olika jordart .er, Sv. ge ol. unders, Ser -, C, N: o 497 . )'fATTILA, J OR M A . 1938,L ohtajan lent ohiot ik ko. K yronmaa IV. Vaa sa. OKKO, V., 1945, Untersuch u ngen tiber den Mik keli-Os, F ennia 69 , N :o 1. -"-"-. 1949,G. B rander's Dat a of the Lit t orina Shore-Line in North an d Mid d le Ost ro bot .hnia . B ull . Corum. geol . F in!. N: o 144 . RICHT E R . K.• 1936, Ergebnisse und A u ssicht on d er Gefugefo rschung im p om m er sch en Diluviurn . Geol. Rundschau Bel. XXVII . R OSBERG, J . E .. 189 5, Bot t envikens finska deltan. Geog r. f or en . m ed d . 2. 1894. 1895. SAKSELA, MARTTI. 1933 , T he General Geological Map of Finlan d . Sheet B 4, K ok kola . Explanation t o t h e map of pre-Cambri an rocks (in F in nish ). Geological Surve y of F inla nd . S.'\L:Ul, ::\lARTTI, 1947, The h ea t value a nd percentage of ash in peat . T oknillin en ai kak ausleh t.i N :o 4 , H elsin k i. _ )_, 1948. 7.wei su bfoss ile T ierk noch enfund o aua P ohjanmaa . Bull. Co mm. geol. F in!. 1\'0 142. SAURA MO, MATTI, 1929, T he Quat or nary Geology of Finland. Bull Co m m. geol, F inl. N: o 86. _ ,)_ , 1939, T h e Mode of t h o Land U ph eaval in F ennosca ndia during La t e-Quat er nary T ime . Bull. Com m . gecl. F inl. N :o 125. S EDERHOL:\I, J . J .. 1887 , Om d e Ieee bildningarna vid b and elen Gamla K a r-leb y Uleuborg. ::\Ied d. fro Jndust r-istyrelaen N :o 4. _+_, 191 3, \Veit ere ~I i t t e il ung en tiber Bruchspalten mit besonder er Beziehung zur Geomorpholcgie von F ennoskandia . Bull. Comm. geo l. E inl , N :o 3 7. T IG ERST EDT. A. F.• 1887 . Beskrifning ofver en pH Bergst.yrelsene fcrordna nde a n sta.lld rosa lungs jtir nvagslinj en fran Ost crmyra st at ion t ill Gamla K arleby . :\Ied d . fr o I ndust ri st yrelse n N :o 4. Vm KKALA, K .; 194 8, T h e Ge neral Geological Mop of F inl and. Sheet D 4. Nurm es. E x pla nation to t he map of surficial dep osits. Geological Survey of Finl and. W ITTING, R . J ., 1943. La ndhojningen utm ed baltiska. ha ve t under aren 1898 1927. F ermin es, N:o 1.