GEOLOGY OF NELSON BAY , ROBBERG,

KARL W. BUTZER Departmentsof Anthropologyand Geography,the Universityof Chicago

Nelson Bay Cave is located on the southern face namely Nelson Bay (or Wagenaar's)Cave and Hoff- of the Robberg Peninsulaon the south-easternCape man's Cave (East Ghwanogat), were probably coast of South Africa,near PlettenbergBay. Co-ordi- initiatedby wave-cuttingat about 15-20 m. However, nates are approximately 230 22' 30" E and 34? 6' 10" S, both of these are developed in a breccia fre- and the mouth of the cave is at about 19-21 m above quently found at the contact of the quartzite of the MSL. Systematic excavations were carried out in Silurian Table Mountain Series and the quartzitic 1964-5 by R. R. Inskeep (1965), and in 1970-1 by sandstone of the Uitenhage Series. The R. G. Klein (1972a, 1972b)and Inskeep(this volume). age of this 'contact' breccia remains uncertain. At The generalgeology and geomorphologyof Robberg Hoffman'sCave the Table Mountainquartzite dips at has already been studied by John Rogers (1966) 100 to N500E,the overlyingContact Breccia at 27-25? and mappedat a scale of 1:7200. Rogers'smeticulous to N700E, and the Uitenhage Series above at 100 work supersedesthe cursoryobservations of the older to N800W. Comparableangular unconformitiesare literature and makes it unnecessary to outline the evident at Nelson Bay Cave, except that the Contact bedrock suite or structure,except in so far as they Breccia dips at 6-9? to N500-90'E. In each case the concern Nelson Bay Cave. caves are almost exclusively cut into this breccia, in The present paper is based on field investigations situationswhere the brecciais unusuallythick and was in 1970 and 1971 followed up by laboratoryanalyses. fortuitouslyexposed in the cliff face in relation to a The results are described in adequate detail since particularsea-level. Just as the Contact Breccia was they are informative beyond the context of the prerequisiteto the developmentof large caves at these archaeological sequence within Nelson Bay Cave. particularsites, this same formationhas remainedthe Most of the existing literatureon cave sedimentology primarylocal source of mineral sediment. refers to limestones or dolomitic lithologies, whereas The Contact Breccia at Nelson Bay Cave can be next to nothing has been published on quartz- subdivided into three units: sandstone and quartzitecaves, of which Nelson Bay (a) The lower bed, over 3 m thick, consists of Cave provides an excellent example. Thus inter- coarse-to-cobblegrade, subangularto angularquart- pretation of this cave sequence poses a number of zite rubble set in a silcrete, sandy loam matrix. interesting and novel problems. Furthermore, the Colours of the matrix vary from white to pale yellow of sediments Nelson Bay Cave providepaleo-environ- and yellow (10 YR- 2,5 Y), dependingon the degree mental information that is related to a relative and of superficial weathering. Stratification of rubble chronometric stratigraphy, and which is comple- limited, sorting moderate. mented by several categories of faunal analyses (Klein 1972a, 1972b) and oxygen isotope studies (b) The intermediatebed, about 1,5 m thick, has presently under way by N. J. Shackleton. These poorly sorted, fine-to-boulder grade detritus, sub- data complement the external sequence of geo- rounded to subangular,set in a comparablematrix. morphological and pedological events (see Butzer Marked stratificationof pebbles. & Helgren 1972), so contributingto an understanding (c) The upperunit, about 2 m thick, is comparable of Quaternary palaeoclimates in the southern and to the lower bed (a), except that stratificationis more south-easternCape Province of South Africa. pronounced. The intermediateand upper beds of the Contact The Origins of the Cave Brecciahave suppliedmost of the coarser detritusin The cliffs of Robberg are punctuatedwith notches, the cave infilling. Superficially, the matrix of the caves and other erosional features that are primarily Contact Brecciais oxidized by weatheringor impreg- a direct result of wave-cutting at various times. nated with some secondarycarbonates. In the process However, the great majority of these features are of disintegration,slabs and splices peel off the roof closely related to lithological variation, bedding, and along the bedding planes. This appearsto be mainly other structuralfeatures of the bedrock.This reserva- in response to pressurereleases, although weathering tion also applies to the bulk of Rogers's inventoryof along fissures and cracks is indicated by superficial possible indicators of former high sea-levels (Rogers corrosionof the siliceousmatrix, presumably through 1966: Table 12), even though the great majoritymay a combination of soil and rain waters, aided by sea- well be relevant to various stages of wave erosion. salt. The quartziterubble within the Contact Breccia Rogers's frequency graph (1966: fig. 17) singles out is another matter. It is jointed and fractured but, two levels of recurrentfeatures that, also in view of despite such potential lines of weakness,now seldom their morphology, must be attributedto former sea- breaks up when detached from the intact breccia levels at about 30 m and again at about 15-18 m. Thus, whereasthe matrix graduallydisintegrates into The two largestcaves on the south face of Robberg, fine-grainedconstituent parts or alteration products, 97 S. Afr. Archaeol. Bull. 28: 97-110.

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions the quartzite rubble remains largely uncomminuted. The SedimentAnalyses Frost is practicallyunknown along the south-eastern Excluding several suites from other sites on Rob- Cape coast today, and only three of twelve climatic berg, a total of 31 sediment samples were collected stations between George and Port Elizabeth have in Nelson Bay Cave during the 1970 season, and ever recorded subfreezing temperatures.In fact the 38 duringthe 1971 season. All of these were processed mean lowest temperatureof each year ranges from in preliminaryfashion while in the field, including +1,4 to +5,30C at these same stations (Climate of determination of colour (dry, from the Munsell South Africa, 1954), and frost or frost-weathering Color Charts),structure, consolidation, stratification, must be totally absent in the far less extreme micro- any calcification or oxidation features, humus and environment of the cave. This does not, however, other organic forms, and estimated texture. preclude the possibility of effective frost-weathering The 1970 collection was subsequently analysed in the Pleistocene at times of cold, pleniglacial in the Paleo-Ecology Laboratory of the University climate. of Chicago, including: (1) Hydrometer analyses, The formation of Nelson Bay Cave was initiated using a 5 per cent solution of sodium pyrophosphate by wave-cuttingat a time when relativesea-level stood as a peptizing agent, and subsequentlypassing the at +15-20 m, judging by maximum roof elevation sand fraction through a set of standard sieves (63, at +21 m and a floor rising from the back of the 210, 595 and 2 000 microns). The samples were cave at +11 m to a rock threshholdat + 18-20 m. previouslydecalcified in 25 per cent hydrochloricacid Wave-generateddeposits are restrictedto beach sands after first removing all shell or bone fragmentsthat and sphericalbeach gravelsin the rear of the cave to did not pass the 2 mm sieve. Secondaryferric concre- a maximumelevation of + 12 m. This presupposesa tions were removed from the final residuesand their low-level entrance, presumablya large fissure along weight subtracted from the original input. The the bedrock unconformity,that has long been filled resulting textures were classified according to the with sedimentbut which once allowed storm waves to U.S. Soil Survey system, with sorting of fines as surge up into the back of the cave. These marine defined by Payne (1942). Sand percentages are deposits at + 12 m presumablyreflect a part of the given as the 63-200 micron fraction. (2) Calcium + 5-12 m sea-levelstage widely representedalong the carbonate determinationsby the Chittick gasometric south-eastern Cape coast and which is most apparatus.(3) pH and mV values, electrometrically, reasonably correlated with the Eem Interglacial in distilled water. (4) Semi-quantitativeestimates of (Butzer & Helgren 1972). In terms of C14 years the sand grain micromorphology and composition, age is substantially greater than 40000 B.P. The including degree rounding, frosting and the ratio of correlationof the preceding+ 15-20 m stage remains primaryquartz to quartzite-derivedsands. The great conjectural,but an early Eemian age now seems very majorityof the samples were furtheranalysed by the unlikely in view of more recent field-work (1973) Soils Department of the University of Wisconsin, at Klasies River Mouth and Swartklip. underthe supervisionof E. E. Schulte,for: (5) Organic The development and gradual enlargement of matter by the Walkley-Blackmethod, which involves Nelson Bay Cave from the + 15-20 m stage to the addition of sulphuricacid to a weighed sample with later phases of the + 5-12 m stage presuppose a standard potassium dichromate; after reaction the considerablespan of time, no matter how indefinite. excess chromate is backtitrated.(6) Available phos- And the cavern is appropriately large, measuring phorus,extracted with 3 per cent NH4F in 10 per cent 36 m long and 18 m wide on a trapezoidalplan, and HC1. In alkalinesediments, such as those represented ranging from 2 to 8 m in height. After the initial here, this method extracts mainly P2 bound to car- notch(es) was cut into the Contact Breccia, enlarge- bonates and in various soluble organic forms. (7) ment followed the relativelyweak bedding planes of Available potassium, mainly potassium salts, by the this breccia and both the north-easterlydip of the standardextraction method. (8) Free Fe2O3,by reduc- rock and the orientation of the cave axis reflect on tion to ferrous iron by Na2S204 in a sodium buffer. this structuralproperty. After the external shoreline Analysis of the 1971 collection was completedafter dropped to below 10 m or so, the fissureat the back submission of this paper (March, 1972) but the key continued to serve as a conduit for rain and ground results are includedhere. water-both to enter and drain away after heavy Beyond the fine-sedimentstudies, 27 collections of rains-and as a sluice for slow sediment removal. crude detritus (greater than 1,5 cm) were studied by However, this exit has been ineffective for all but the various morphometric techniques, primarily solubles and clays since waves ceased to flush it out. modified after those of G. LUttig,outlined by Butzer This can be deduced from the estimated 1 000 m3 of (1971: 166 ff): (a) p is the index of rounding; (b) CV mineral sediment preserved,none of which appears of p is the coefficientof variation to express the uni- to predate the + 10-12 m beach deposit and a third formity of rounding properties;(c) E/L and E/i are of which is extraneous.Yet at least 3 000 m3 of Con- ratios that provide indices of flattening, with L the tact Breccia were destroyed during the course of major axis, 1 the minor axis, and E the height of the cavern formation, so that a volume of as much as pebble. Finally some 4 600 pieces of 'non-artefactual' 2 500 m3 was removed prior to the time of the stone were lithologically classified. + 10-12 m beach. The more important categories of analytical data 98

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions TEXTURE CaCO3/pH PIT FILL 0 Iy adp

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-25 40 ~~~~~~~2'060 806 % 20/ 4'0/ 60/ /8.0 6.5 7.0 7.5 Fig. 1. Composite SedimentaryProfile of the Main Excavation, Nelson Bay Cave. Texture refers to matrix of non-carbonateresidues under 2 mm.

99

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions are summarizedin figures 1 and 2, and are incor- mass of humic sandy or silt loam with lines and con- porated into the subsequent sections describingand centrationsof stratifiedcrude rock. The approximate then interpretingthe sedimentaryunits. sequenceof the deep pit is as follows: (a) The lowest ferruginous zone (Oxidation Horizon Ia) is a dis- The Strata of the Main 1970-1 ExcavationArea continuous level of stone concentrationsin a matrix The sedimentaryunits exposed by Klein's excava- of brown (10 YR), loam with many, coarse and tions in 1970-1 consist of a lower suite, primarilyof distinct mottles of reddish yellow (7,5 YR) colour. natural origin, and an upper one that is primarily (b) 10-15 cm. Dark gray brown (10 YR), humic silt composed of culturalhorizons and shell heaps. These loam with coarse, angularblocky structure.Abundant are here described,beginning with the mineral sedi- hearthdebris. (c) 5-8 cm. Partlycemented, yellow red ment units, using the field nomenclatureas a matter (5 YR), stony sandyloam with darkred brown(5 YR), of convenience. Unless otherwise stated, units are ferruginouslaminae (Oxidation Horizon Ib). Abun- uncementedand moderately compact, sorting poor, dant artefacts, some charcoal and fired, red (10 R) and contacts abrupt (0-2 cm) and straight or wavy. loam. (d) 15-20 cm. Dark gray brown (10 YR), For discussion of radiocarbondates see Fairhall & humic, sandy loam with medium subangularblocky Young (1973) and Klein (1972a). structure. Dispersed crude rock and many distinct Basal Loam. 0-15 cm. Very pale brown (10 YR), coarse mottles of red yellow and yellow (7,5-10 YR) sandy loam with coarse angular structure. Few, colour. Artefacts and common traces of fired, red distinct yellow (10 YR) mottles, with limonite or (10 R-2,5 YR) loam. (e) 5-10 cm. Crude rock with a pyrolusite staining of former organic impressions. basic matrix of gray to dark gray brown (10 YR), Closely similar to weathered matrix of subjacent humic sandy loam, and pockets of loamy sand. In bedrock (Contact Breccia). Stratum dips 25-30? large part ferruginizedin bands of diffuse stains of laterallyto axis of cave. prominent red yellow (7,5 YR) or dark red brown Pale BrownLoam. 60-90 cm. Pale brown (10 YR) (5 YR colour; surface semicementedand smoothly sediment very rich in organic colloids, grading eroded (Oxidation Horizon Ic). Masses of stone upward from loam to clay and from weak medium, artefacts, traces of bone and fired, red (10 R) loam, subangularblocky to strong, coarse angular blocky with organicmatter rangingfrom 1,8 to 8,4 per cent, structure.Common, distinct yellow (10 YR) mottles phosphorusonly 35 to 85 p.p.m., potash 100 to 200 in top 10 cm. Dispersed stone throughout,including p.p.m. Despite basal irregularities,horizon is almost several blocks of kaolinized and oxidized (yellow horizontal towards cave axis but dips 6-7? to back. 10 YR) Contact Breccia from roof. Two samples RubbleHorizon. 0-15 cm. Discontinuous level of showed abundant and varied organic impressions crude rock, consisting entirely of quartzite with and all contain 5,5-9,0 per cent organic matter. Phos- conspicuous corrosion of edges. Originally lacked phorus levels vary from 25 to 150 p.p.m., potash fine materials with incomplete matrix derived from 145 to 200 p.p.m. Three discontinuous lenses (less overlyingbed. Morphology and random distribution than 1 cm to 5-8 cm thick), rich in carbonaceous comparable to modem, dry caves with very slow materials and charcoal fragments, are derived from accumulationof rock. hearths; they dip 18-300 towards cave axis. The GrayLoam I. 20-50 cm. Brown to dark gray brown stratum itself dips only 15-20?. (10 YR), silt loam, with structureranging from weak, Black Loam I. 25-50 cm. Dark brown (10 YR), medium, subangular blocky to strong, very coarse humic loam, with moderate, very coarse, angular angular blocky or prismatic. Dispersed crude rock blocky structure.Concentration of crude rock and a near front of cave. High concentrationsof phosphates few, distinct yellow (10 YR) mottles in upper part, and potash in back of cave, with low to moderate organic concentrations(? reworkedhearth) at base. humus content (0,8-4,5 per cent), indicating organic Organic matter varies from 4 to 8 per cent, phos- compounds.Dips 3-12? (average60) to back of cave, phorus 100 to 175 p.p.m. and potash 240 to 300 p.p.m. with increasingevidence of oxidation in large pockets Bed thins a little but remainshorizontal towards back of common, distinct red yellow (7,5 YR) mottles, of cave, and dips an average of 190 towards centre. some ferruginouslenses, and pyrolusite on red faces Black Loam II. 30-60 cm. Brown (10 YR), highly (Oxidation Horizon 2). Upper contact very wavy, humic loam to silt clay loam, with coarse subangular and clear to diffuse(2-10 cm). to angular blocky structure. Dispersed crude rock Gray Loam II. 0-30 cm. Discontinuous bed of and a few, distinct yellow (10 YR) mottles. Artefacts brown to pale brown (10 YR), silt loam, with coarse, and traces of fired, red (10 R) loam or rock record subangular blocky structure. Rare, dispersed roof occupation, as do 7,5-10,0 per cent organic matter, detritus.Top dips 1-8? to back of cave. 130-150 p.p.m. phosphorus and some 200 p.p.m. Yellow Stony Loam. 20-50 cm. Complex, inter- potash. Maintainingconstant thickness,this bed dips fingering lenses that allow local differentiationinto 6-10? to back of cave; laterally, the base dips 190, as many as three subunits: (a) Basal 0-20 cm. Light but upper boundary uncertain, possibly demarcated yellow brown (10 YR), loam to silt loam with dis- by undulating stone concentration. persed crude rock. (b) Intermediate10-20 cm. Pale Black Loam III. 30-70 cm. Alternatingferruginized to very pale brown (10 YR), loam to silt loam, with and non-ferruginous horizons in a high-variable local fossiliferous pockets of micro-fauna. (c) Top 100

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions 10-20 cm. Light yellow to brown yellow (10 YR), humic loam, interbeddedwith very dark horizons of silt loam, with dispersed crude rock, grit horizons fine charcoal, phosphates (105 p.p.m.), and ash, as or lenses of crude rock, includingkaolinized slabs of well as white shell ash. C14 date on carbonaceoussoil: Contact Breccia; locally with some phosphates and 5825 ? 125 B.P. (UW-187). potash; fossiliferous pockets of micro-fauna; oxida- HIG. 10-20 cm. Packedshell and hearthswith some tion ranges from a few, distinct red yellow (7,5 YR) matrix of light brown gray (10 YR), humic loam. mottles to extensive yellow (10 YR) banding or BSBB/I. 10-35 cm. Gray brown (10 YR), humic general discoloration (Oxidation Horizon 3). All sandy loam with hearths, phosphates (110 p.p.m.), horizons include artefacts,some bone, and fragments bone and some corroded shell. C14 dates on car- of shell. Carbonaceoussoil from the middle of the bonaceous soil; 6020 ? 160 B.P. (UW-176) and yellow Stony Loam gave a C14 age of 18100 B.P. 6050 ? 80 B.P. (UW-186). (UW-175), possibly too young as a result of contami- B/I. 10-55 cm. Packed shell and ash horizons with nation by younger organic acids. A second date, of matrix of light brown gray (10 YR), moderately 18660 ? 110 B.P. (GrN-5889)on shell (Vogel 1970), sorted, sandy loam. Interbeddedwith 2-5 cm lenticles probably comes from this horizon. Overall dip is of clean well-sorted, coarse sand of eolian origin. 2-5? to back of cave. C14 date on shell: 5350 + 65 B.P. (UW-217). Brown Stony Loam. 10-30 cm. Gray to very pale GAL.0-20 cm. Loose shell, shell ash and hearths brown (10 YR) loam, with dispersedcrude rock and with matrix of gray (10 YR), humic loamy sand. medium, subangular blocky structure. Contains Pit Fill. 0-50 cm. Mixed cultural debris, largely artefacts, bone and some shell. Dips 2-50 to back derived, with matrix of light brown gray (10 YR), of cave. humic, moderately sorted, loamy sand. This completes the sequence of essentially natural A suite of youngerstrata are exposed in the Inskeep sediments, and the overlying suite consists primarily excavations at the threshold of the cave. These of cultural strata. All contacts are abrupt and wavy, remainto be studied,but this segmentof the recordis with most beds showingpronounced lenticular sorting complementedby the fill of Hoffman's Cave, which into decalcifiedorganic-mineral residues, hearths, or shows eolian deposition continued unabated until shell heaps, frequentlywith complex interdigitation. 4200 B.P., with some stabilizationthereafter (Butzer Abbreviated field designations (see Klein 1972a; & Helgren 1972). 1972b)are utilized in the following description. The Nelson Bay Cave strata below the Rubble GSL. 10-15 cm. Occupation residues including Horizon include severalvariants of the Middle Stone conspicuous hearths, fired sediments (red to light Age. The Gray Loam lacks artefacts in the Main red brown, 7,5 R-2,5 YR) and decalcifiedshell ash. Excavationarea, while the Yellow and Brown Stony Highly variable in colour and composition, with Loams have a Late industry, as yet texture generally that of an inhomogeneous loam unnamed (Klein 1972a, 1972b). Levels GSL through with rare crude rock. C14 date on charcoal: 11950 ? J have 'Pre-Wilton' (as used by Deacon 1969), 150 B.P. (UW-177). levels Rb through GAI 'Climax Wilton', both Late CS. 20-35 cm. Gray brown (10 YR), loam with Stone Age industries(Klein 1972a). abundant crushed shell and several hearth horizons with potash enrichment (250 p.p.m.). C'4 dates on The Strata of the Sump Pit charcoal: 11540+110 B.P. (UW-162), 10285 ? 85 The stratigraphic information from the Main B.P. (UW-164) and 10150 ? 90 B.P. (Pta-392). Excavation area is complementedby that from the BSBJ. 25-35 cm. Loose shell, bone debris and Sump Pit dug in 1971 to help lower the watertablein hearths with matrix of light brown gray (10 YR), the cave. The strataare describedbelow with reference humic loam with rare crude rock and potash concen- to figure 2: tration (210 p.p.m.) C14 date on carbonaceoussoil: (a) Greater than 40 cm. Stratified, loose, clean, 10540 ? 110 B.P. (UW-178). very pale brown (10 YR), sorted coarse sand as J. 20-25 cm. Loose shell debris, fired horizons and matrix to well-rounded beach gravel, subrounded hearths with a matrix of light brown (10 YR), sandy crude rock from roof, and occasional waterworn clay loam with rare crude rock. C14 dates on charcoal artefacts.Upper contact gradual. and carbonaceous soil from hearths at contact (b) 30 cm. Well-stratified,weakly structured,light between J and overlying bed Rb: 8990 ? 80 B.P. gray (10 YR), sandy loam as matrixto grit and coarse (Pta-391)and 8120 ? 240 B.P. (UW-181). gravel that grades upwards from a beach facies to Rb/Rc/Rc/C. 30-50 cm. Loose, partially crushed increasinglyangular, crude rock with greaterorganic shell and shell ash, with limitedmatrix of light brown components organic matter 3,0 per cent, phosphorus gray (10 YR), loam. C14 date on marineshell: 8570 ? 188 p.p.m. and potash 135 p.p.m. Artefacts and 170 B.P. (UW-184). debitagenot waterworn.Upper contact clear (2-5 cm). Ra. 10-20 cm. Packed shell, with a little matrix of (c) 50 cm. Well-stratified,packed, crude angular light brown gray (10 YR), loam. C14 date on shell: breccia of quartzite and kaolinized Contact Breccia. 9080 ? 180 B.P. (UW-179), on charcoal: 6065 ? 125 Incomplete matrix of gray brown (10 YR), humic B.P. (UW-222). (3,9 per cent organic matter) loam with crumb BSBH/G 15-35 cm. Dark gray brown (10 YR), structure and many, prominent and large mottles

101

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions TEXTURE CaCO3/pH (g) |C lay /iltS CaCO3 pH g) A

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25 (a) *~* 0 20 40 60 80 % 201 40/ /8.0 /8.5 7.0 7.5S Fig. 2. GeneralizedSedimentary Profile of Sump Pit, Nelson Bay Cave. Not to scale. Texturerefers to non- carbonatematrix. of red brown (2,5-5 YR) colour. Hearths and arte- p.p.m. potash. Upper contact abrupt and straight. facts 175 p.p.m. phosphorusand 425 p.p.m. potash. (e) 7 cm. Weaklystratified, yellow brown (10 YR), C'4 date pending on fine charcoal. Upper contact silt loam with coarse angular blocky structure. abrupt (0-2 cm) and wavy. Artefacts and ash traces. Upper contact abrupt and (d) 30 cm. Massive and compact, dark gray (10 straight. YR), loam to silt loam with strong medium angular (f) 5 cm. Well-stratified,pale brown (10 YR), blocky to prismaticstructure. Common, faint, yellow loam as matrix to occupation debris, with 2,4 per (10 YR) mottles in lower parts, but the top 0-15 cm cent organic matter, 175 p.p.m. phosphorus and show many, large and distinct mottles of red yellow 260 p.p.m. potash; many, large and distinct mottles (7,5 YR) colour in which ferric precipitates create or bands of yellow (10 YR) colour. Upper contact a crumb structure. 4,5 per cent organic matter, abrupt and straight. 90 to over 250 p.p.m. phosphorus and 320-675 (g) 10 cm. Laminated, compact, brown to. light 102

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions gray (10 YR), loam with occupation debris and fine heating and the creation of repeated intermineral lenticles of shell ash. stress. However, alternation of heating and cooling The artefactsfrom beds (a) through (d), although have proved of limited effectiveness in laboratory small in number, are of type, studies, while few of the major hearth horizons in while those of (e) and (f) are too few to be diagnostic; Nelson Bay Cave have any cruderoof rubblein them, unit (g) is probablyWilton (R. G. Klein, pers.comm.). so that this factor is of limited importanceat best. The Sump Pit section is separatedfrom the Main (iv) Chemical weathering can operate in initial Excavation by some 12 m, and there are no direct rock disintegration as well as in subsequent, i.e. stratigraphiclinks. Although the beach deposit at postdepositional,alteration. Exposed rock is generally the base of the Sump Pit is unique, other sedimentary covered with saline solutions or salt precipitatesas a propertiesare not. In particular,the three oxidation result of the saline 'sea mist' generated at times of horizons (beds c, d and f) invite correlation with high wave agitation. Such salts swell and contract in those of the Main Excavations. Next the breccia, response to changes of moisture and temperature bed (c), is lithologically comparable with Black (see Evans 1970). In porous rock, such as the matrix Loam III, while the prismatic-structured,compact of the Contact Breccia, salts can create intermineral bed (d) is identical on all counts with Gray Loam I stress, with granulardisintegration as well as splicing (23,5 per cent clay in Sump Pit compared with off of superficial fragments by concentrated salt 27 per cent in Main Excavation, 14,5 per cent sand efflorescenceor subflorescence.A second mode of to 12 per cent, 5,0 per cent CaCO3to 3,4 per cent, chemicalweathering is the slow corrosionof quartzose 4,4 per cent organicmatter to 3,7 per cent 675 p.p.m. and silcretematrices by percolatingand condensation potassium to 685 p.p.m., and both greater than waters that are moderatelyalkaline as a result of the 250 p.p.m. phosphorus). Since the sedimentaryand abundantsodium salts. As a consequence,roof rock oxidation-alterationcriteria match, we have no hesi- is superficiallyimpregnated with minute quantitiesof tation in correlatingas follows: evaporite that react to hydrochloricacid, while the SumpPit Main Excavation subcutaneous rock is abnormally porous and may Beds (e) and(f) Yellow Stony Loam (Oxidation even break down in acid. Furthermore,some parts of Horizon 3) the roof show oxidation or secondaryimpregnation Bed (d) Gray Loam I (OxidationHorizon with iron oxides, as well as kaolinization. Finally, 2) algae, fungi, lichens and bacteria are present in Bed (c) Black Loam III (Oxidation Hori- varying proportions and concentrations on rock zon 1). surfaces or in fissures, contributing an uncertain component of biochemical and biomechanical There is no direct correspondencefor either the changes and stresses. The impact of these complex basal beach or bed (g). The top of the mixed beach- chemical agencies is to aid in spalling or grain-by- cave facies of bed (b) is at c. 12 m above MSL, which grain disintegration of the matrix of the Contact is the elevationof the lowest depositsof Black Loam I Breccia, loosening out the quartzite rubble, which in the Main Excavation.It is thereforeprobable and may be superficially corroded. Most of the fine lithologically reasonable that the Black Loam is detrital component is obtained in this way, while broadlyequivalent to the detritalbed (c) in the Sump postdepositionalalteration further breaks down the Pit. This would imply that the beachproper is at least Contact Breccia matrix into kaolinized and/or in part contemporarywith the Pale Brown Loam. oxidized material that ultimately returns to its com- At the top of the column, bed (g) was deposited in ponent parts as a 'cave earth' with releasedquartzite standing waters, a facies also absent in the Main rubble. Excavation. The closest resemblance is with level (v) Stone tool manufactureproduces crude detritus GSL, or possibly, the Brown Stony Loam. that ranges a full spectrum from well-fashioned implementsto Interpretationsof the GravelMorphometry incidentalstone chips. Since almost all of the raw material used was quartzite, bulbless The crude detritus in Nelson Bay Cave has been artefactual debris is difficult to distinguish from produced or modified by several agents that require natural rock splices. It was consequently necessary some discussion. to examineall crudedetritus for percussionbulbs and, (i) Spallingof the Contact Brecciaof the cave roof since these are poorly developedin fissuredquartzite, is primarily a result of dilation and fracturing, in the gravel analyses systematically excluded 'fresh' response to pressure release through active under- angular flakes with elongated, tapering shapes. All mining of the cavern. flakes or chunks of exotic rock, viz. chert, jasper, (ii) Accelerated spalling can result from frost- agate and vein quartz,were also rejected.In this way, weathering, the products of which should be more debitage was excluded from the sample, although angularand flatteras well as less oxidizedor corroded unmodified manuports in quartzite or quartzitic than rubble due to the slower process of pressure sandstone are next to impossible to recognize. release. The many agencies capable of producing crude (iii) Thermoclasticweathering in response to fires detritusin Nelson Bay Caveemphasize that the gravel in a cave will favour spalling by means of differential morphometryis difficult to interpret. None of the 103

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions indices selected for analysis provides conclusive stratigraphicboundaries, although the strong cemen- results, seen in isolation. Thus, all of the samples tation of crude detritus into a few horizons mini- above the beach deposit are angular to subangular, mizes the effect of 'smoothening'the overall curves. heterogeneous in terms of rounding, highly detrital, Finally, the sampleswere not uniformlyselected from and conspicuously flat (as opposed to spherical) in the Table Mountain Quartzite rubble released from shape (fig. 3). Basically this reflects the fractured and the Contact Breccia: without careful microscopic inhomogeneous nature of the once strongly-jointed examination it was often impossible to distinguish quartzite rubble embedded in the Contact Breccia. quartzitic sandstone or weathered quartzite of the In other words, the primary morphological and Table Mountain Series from more quartzosesamples morphometric traits are inherited. This is compli- of Brecciamatrix or, possibly, from occasional pieces cated by the presence of some primary changes in of quartzitic sandstone from the Uitenhage Series rubble morphometry among the quartzite rubble that may have been washed or carriedinto the cave. within different strata of the Contact Breccia. Samples Although the samples measured were homogeneous from the Pale Brown and Black Loams are further in a purely lithological sense, within a reasonable skewed by their collection from 20 cm horizontal spectrum of quartzite and quartzitic sandstone, a spits in what are, in part, dipping strata (fig. 3). The small and variable percentage of younger rock was result has been to mix several of the samples near unavoidable.These many caveats emphasize that the

10 20 30 40 % 10 20 30 40 50 60 7080 90 %

YELLOW _ Coefficient of < Detrital *O. HOIndex Ferruginization Variation (14) E/L [lL J STONY dLPCopnt Cop LOAM 00 ~~~16

LOAM 14 12/ 131.5A/'//' ...... HORIZONGAYllllillluull' 13

BLACK

7 LOAM

PALE BROWN LOAM

3

cure f fr eblesloge tan10cm

[m Bedrock'~

BEACH O 0

Fig. 3. MorphometricGravel Analyses from Nelson Bay Cave. Index of rounding(p), indices of flattening(E/L and I/L, where B is thickness,L major axis, 1 minor axis), ferruginizationindex (per cent of rock fragments ferruginizedand discolouredfrom total lithological sample), coefficientof variation of p (divided by 4), and detritalcomponent (per cent p ? 8 per cent). Restrictedto pebbles 2-10 cm in length, except for one separate curve of p for pebbles longer than 10 cm. 104

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions graphic results of figure 3 cannot be interpreted slow rate of sedimentation. mechanistically.None the less, several of the con- The Rubble Horizon is a selectivequartzite residue, vergent trends are both significant and diagnostic. with 86 per cent of the lithological spectrum (264 The beach gravel (no. 1, fig. 3) is quite unique in pieces identified)quartzite, compared with ranges of terms of a high mean roundingindex and a relatively 47-73 per cent in the underlyingand overlyingstrati- homogeneous degree of rounding, despite the pre- graphic units. Only 1,1 per cent of the quartzite sence of many subangularpieces of partly-modified retainedadhering matrix, as comparedwith 2,8-16,2 roof debris. Unusually high sphericityis indicatedby per cent in the other levels. Another 1,1 per cent of both the E/L and 1/L ratios. This must be attributed this sample consisted of oxidized matrix, compared to a dominance of rolling over sliding motions in with 4,6-29,8 per cent in the other levels. The remain- transport, presumably as pebbles were churned ing 11,4 per cent consisted of quartzose matrix. around in a confined space by indirect wave action. Thus, the lithological composition of the Rubble However, wave surges can 'pile up' at least 2 or 3 m Horizon is unique. A second characteristicof this in confinedrock fissuresduring periods of high seas, level is that 60,3 per cent of the rubble (greaterthan so that beach pebbles to a maximum elevation of 2,0 cm in major axis) falls into the size class over 12,5 m may have been generatedwith a MSL of no 10 cm, compared with only 15,4-49,9 per cent in more than +9 or 10m. the other horizons. Furthermore,the extreme size The gravel from the Basal and Pale Brown Loams grades of 20 to over 35 cm are not even represented (nos. 2 and 3, and the mixed sample 4, fig. 3) repre- elsewhere in the sequence. This, and the relatively sents quartzite released from the Contact Breccia high sphericity, suggest no comminution of the with little mechanical change. Some 24-33 per cent quartzite rubble released from the Contact Breccia. of the total lithological collection from these levels The last hallmarkis a conspicuous,yet very superficial consists of oxidized matrix, in part attached to corrosionon the edges of most pieces, a phenomenon quartzitefragments, and in most cases in process of present in the modern crude detritus that litters the decomposition. floor of Nelson Bay Cave and other Robbergshelters. Within Black Loams I and II there is a notable However, this edge-corrosionis insufficientto modify increasein angularcomponents (from 40-60 per cent the index of rounding appreciably. to 70-85 per cent), a trend to increasedmean angu- Altogether the Rubble Horizon, which is just as larityand heterogeneity,as well as reducedsphericity. distinctiveas the beach gravel, must be attributedto In sampleno. 9, mechanicalfracturing is so ubiquitous weatheringagents and rates similarto those of today. that practicallynone of the quartziterubble from the The modem counterpartsare also similar in respect Contact Brecciaremained unmodified; this subjective to quartziteconcentration, large calibre, and absence evaluationis verifiedby the unusuallylow coefficient of fine matrix. The single problem of interpretation of variation.Some 80 per cent of the relatedlithologi- surroundsthe lack of fine matrix, since the selective cal samples consist of fresh, i.e. unoxidized and nature of the quartziteresidue can only be explained undecomposed, rock which, in view of the highly by total disintegrationor decomposition of almost humic and otherwise fine nature of the basic sedi- all of the less resistant Contact Breccia matrix. The ments, must be attributed to accelerated spalling best explanationis very slow breakdown,allowing fine rates rather than to reduced chemical weathering. weatheringproducts to be removedby erosion about Finally, the subjective impression of the rubble in as rapidly as they formed. It is therefore highly these strata is unequivocallythat of fresh, cryoclastic probable that the Rubble Horizon marks a pro- debris-with marked comminution in size of the tracted period of very slow weathering, certainly parent quartziterubble into a striking proportionof without frost, and presumablyin relation to a tem- highly angularrock splices, lackingany trace of edge- perate or warm external environment. corrosion. By all criteria the crude detritusof Black Interpretationof the gravel data from the Gray Loams I and II must be primarilyattributed to accele- Loam and Yellow Stony Loam (nos. 14-17) is rated spalling as a result of frost-weathering.This is difficultand somewhatequivocal because of a number particularlyso in the case of samplenos. 5, 7, 8, and 9, of minor contradictions between the trends of the with the likelihood that sample 6 marks less extreme differentindices. For the lower Gray Loam and the conditions. upper Yellow Stony Loam, there is a reasonablebut Black Loam III shows declining angularity, an inconclusive case for some frost-weathering and increasein unmodifiedquartzite chunks, an irregular colder climatic conditions. The overall subangular but none the less conspicuous increase in sphericity, class of rounding is partly due to the presence of and a high percentageof oxidized rock specimensin unmodified roof quartzites-many of these sub- the total lithological sample- the last property due rounded-in all of the samples, and in the case of in large part to postdepositionalferricretion. The suite Gray Loam I is accentuated by evidence of edge- of samples 9 through 11 can best be interpretedby a corrosion, possibly as a result of slow sedimentation decline in frost effectivenessand, by implication, a rates. The writer feels that the Gray Loam I and warming trend. This is compatible with the other upper Yellow Stony Loam fall well outside of the sedimentaryproperties, viz. sorting by runningwater, range of variation of either the Pale Brown Loam or post depositional ferricretionand, ultimately, a very the Rubble Horizon, and that they suggestweathering 105

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions environmentsintermediate between those responsible tion of quartziticsandstone, and there is little positive for the Pale Brown Loam and the indisputablycryo- evidenceof beach sands except at the base. Finally, as clastic Black Loam. However, the sum of fracturing discussed above, the crude detritus indicates accele- evident in these upper strata couldhave been a result rated roof spalling with frost-weathering. of weathering agencies other than frost. This only In Black Loam lI the record of human and animal serves to emphasizehow anomalous the cold climate occupance is even more intensive, with significant of Black Loam II must have been. organicresidues. Sands are essentiallyautochthonous The trude rubble of the cultural horizons post- in origin, although rounded, extraneous quartz is dating 12000 B.P. was far too limited for systematic presentin the upperhalf of the bed. Frost-weathering study, and probably was overwhelminglydisturbed attained a maximum.This unit fills in the persistent or -importedby man. hollow along the axis of the cave and beddinghas not been appreciablydisturbed. By the time sedimentation GeneralInterpretation of the SedimentSuite came to a close, the cave floor was almost level but Following the descriptionof the sedimentaryunits with a distinct, general dip towards the back. The and the specific interpretationof the gravel analyses, reasons for the steep lateraldips and apparentslump- it is now possible to attempt a more generalexplana- ing of the precedingstrata are obscure, but under- tion of the depositionalhistory of Nelson Bay Cave. mining by erosion is a good possibility. The Basal Loam is quite similar to weathered Deposition of Black Loam III initially continued Contact Breccia, and the shallow, irregulardevelop- the trends evident in Black Loam II. Considering ment suggests a residualproduct derived in substan- the substantiallylower levels of organic matter and tial part from weatheringof the cave floor, rather phosphorus, and the great abundance or artefacts, than disintegration of roof materials. A relatively man was now directly or indirectly responsible for damp and probably temperatemicroclimate can be most or all of the organicresidues. In fact the irregular inferred.The presenceof a few artefactsand admixed, stone horizon at the base may demarcatea numberof diffuse organic matter-in limited but discernible shallow pits, so that future excavation of this quantity- speaks for cave occupation at this early importantMiddle Stone Age horizon may well reveal stage, quite possibly preceding accumulationof the the presence of archaeological features. Unfortu- beach deposit at the back of the cave. lately, the watertableduring the 1971 excavationswas The Pale Brown Loam is a thick deposit containing so high that it was impossibleto maintainsuch close unusually high proportions of organic colloids and vertical and horizontal control. The later units of clay, with low proportions of crude rock. This Black Loam III coincide with lines of crude detritus suggeststhat much of the finersediment is extraneous, with increasinglycoarse and better-sortedinterstitial rather than derived from disintegrationof Contact materials.Since these sands show no eolian or beach Breccia. The high frequency of rounded quartz properties, it is most probable that these terminal grains among the angular, quartzite-derivedsand sediments reflect on selective sorting by running indicates that beach sands were introducedin some water. Wet conditionsare also implicitfrom the post- quantity. It is likely that short-distanceeolian trans- depositionalferruginization. port, from a beach near the cave entrance, was a Oxidation Horizon 1 dips 50 or more from the significantdepositional agent during the later stages front to the back of the cave, with ferruginization of accumulation.This would be a reasonable inter- in close proximity, i.e. 30-40 cm, of the former pretation in conjunction with the beach deposit at surface. This and the lack of systematicmottling at the base of the Sump Pit, assumingthat the two facies depth both indicateimpregnation by iron-richsurface overlap in time. However,the concentrationof beach percolation or lateral seepage waters, rather than sands within the upper Pale Brown Loam could just oxidation at the watertable.It is possible that such as well reflect on a younger transgressionto a level impregnationbegan during the last phases of sedi- considerably below + 10 m. Finally, all of these mentation of Black Loam III, and that these deductionsmust be consideredas tentative since the mineralizingsolutions are responsible for the local Pale Brown Loam is reworked, as indicated by its preservation of fragmentary bone. In any event, steep, wavy bedding. In view of the oxidized nature ferruginization continued for a protracted period of the crude detritus, conditions in the cave appear after sediment removal had begun to exceed local to have been damp and roof spalling relativelyslow sediment supply. The presence of abundant, perco- duringprimary accumulation, or during redeposition, lating waters rich in sesquioxides presupposes an or both. The organicmatter, phosphorus and clay are unusually wet, external climate with more active best explainedby organic residuesintroduced by cave chelation than is evident today. However, the domi- animals and man. Several discrete occupations by nance of anhydrous forms of iron suggests marked Middle Stone Age groups are indicated by the dis- seasonality of cave moisture or, otherwise, a subse- turbed but none the less clear hearth horizons; bone quent period of quite dry microclimate.No record is unfortunatelynot preserved. of prehistoricoccupancy is preservedfrom this long Black Loam I is also redeposited,while preserving interval of non-deposition,and the crust-likesurface basic stratigraphicorder. The sand fraction is domi- was scouredclean by runningwater before or during nated by the angular grains derived from disintegra- accumulationof the Rubble Horizon. 106

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions The Rubble Horizon, whose genesis has been limoniticzones suggesta slow impregnationof surface discussed already, was ultimately buried by Gray sediment by water dripping from the ceiling and, Loam I, in many ways similar to Black Loam I. since the pH was high, ferric solutions would have Strong organiccomponents are indicatedby well over been precipitatedalmost immediately.The presence 250 p.p.m. phosphorus and 600-700 p.p.m. potas- of hydrated iron- in contrast to the dominance of sium, although organic matter in the restrictedsense anhydrous forms in earlier oxidation horizons- ranges from 3,5 to 4,5 per cent only. Artefacts are indicates that the cave environmentwas perennially lacking in the Main Excavationarea, although there moist at the time of impregnation,and that the sub- are traces of charcoal and of partly-corrodedshell soil has remainedmoist ever since. The final oxida- fragments(recognizable microscopically). Phosphates tion horizon(s) finds a parallel evolution of humic in a quartzite cave must be attributed primarilyto soils on nearby coastal sands, terminating a little faecal residues or bone derivatives,while the bulk of before 16000 B.P. (Butzer & Helgren 1972). the potashcan only be ascribedto wood ash. Although The Brown Stony Loam appears to representthe the phosphates, in isolation, could be attributed to mineral residue remaining after almost complete decomposed owl pellets or to the faeces of undeter- decompositionof shell and other organicrefuse, inter- mined mammals,the presenceof abundantwood ash mixed with natural sediment derived primarilyfrom and shell fragments points indisputably to human the cave roof. Compared with the youngest cave occupancy, as of an intensity unrivalled thereafter. strata,the natureof the humificationand compaction, The restriction of artefactual remains, of Middle as well as the decalcification, suggest a relatively Stone Age type (Klein, pers. comm.), to the back of damp microclimate. the cave as exposed in the Sump Pit is therefore The thick complex of hearths and middens that enigmatic. comprises strata GSL through GAI are primarily Ferruginizationof the topmost Gray Loam I pro- 'cultural'sediments. They provide fascinatingexam- ceeded with respectto a surfacedipping an averageof ples of accelerated sedimentation, periods of non- 60. However,Oxidation Horizon 2 is morphologically deposition, complex interdigitation, and periodic distinct from the banded, partly-induratedferric leaching-all related directly to human occupance. precipitates of Black Loam III. This may reflect The C14 dates indicate that the time interval from on the more impermeablenature of Gray Loam I, 12000 to 5000 B.P. is representedby a discontinuous which is poorly sorted and rich in silt. The strong suite of beds. prismatic structure of the surface of this bed near Several points of interest can be summarized: the back of the cave, where Gray Loam II is absent, (a) The three lowest beds (GSL, CS, BSBJ) are suggests a long hiatus during which the cave floor decalcifiedand the mineral spectrum is still broadly was alternatelyvery wet and relativelydry. Impregna- comparableto that of the Brown Stony Loam. These tion by percolating,ferric solutions and a dominance horizons were deposited with few major temporal of anhydrousiron are best associatedwith this period breaks between about 12000 and 10000 B.P. The of seasonal soaking. condition of these deposits suggestsa dampermicro- Grey Loam II suggests a similar origin to that of climate than that coeval with accumulation of the Grey Loam I, but there is considerablyless diffuse overlying strata. Such an interpretationis corrobo- humus. Despite the continued absence of artefacts, rated (either for the Brown Stony Loam or GSL) there also are traces of charcoal and shell fragments. by the subaqueousdeposit (g) of the Sump Pit. The Yellow Stony Loam records two or more (b) Beginning with level J, rounded quartz sands intervals of accelerated roof spalling, and high become conspicuous and, except for the midden Ra, proportions of the sands and grit reflect on disinte- sands remainthe leadingsize componentof the loose, grating Contact Breccia. Particularlyinteresting is mineral matrix (see fig. 1). With level B/I the sand the preservationand abundance of bone, including component becomes typically eolian with a strong pockets of rich micro-faunalremains, and of horizons grade-size maximum near 100 microns, improved of shell fragments and artefacts. This would imply sorting, and with rounded quartz far outweighing that the pH has remained relatively high since the quartzite-derivedsand of local provenance.Primary time of deposition, and that man and owls alter- lenticles of eolian sand occur in the midden complex nated in their use of the cave. B/I and sand grains frequentlyshow typical micro- Roof spall near the cave entrance shows a high pitting or 'frosting'(but see reservationsin Butzer & incidence of oxidized Contact Breccia (see fig. 3), Gladfelter 1968: 473 ff. on the implicationsof frost- not necessarily embedded in an oxidized sediment ing). The inconsistent C14 dates appear to indicate matrix. This would suggest that much of the sesqui- that the complex of beds J, Rb and Ra were deposited oxide in this stratum first accumulated during with few major interruptionsc. 9000-8000 B.P. The weathering of the cave roof. However, the typical appearanceof eolian, littoral sands is consonant with mottling of the upper units (Oxidation Horizon 3) the increasingsignificance of fish remainsand marine militate for at least some postdepositionalalteration. birds (Klein 1972a). The superficial nature of the oxidation level, the (c) After another break, the sedimentary data 2-5? dip, and the presence of shell all argue against indicate a major phase of habitation during the a high, perched watertable. Instead, the shallow accumulation of the horizontal complex BSBH/G, 107

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions NELSON BAY CAVE

CORRELATION C14 AGE(B.,P.) STRATA INDUSTRIESMICROCLIMATE

ZLU 0j B/I, GA IWarm, 0 5 BS H/G,G,I CLIMAX Dry 0o ~~~~~~~~6,00088? BSBH/G 586/ WILTON 9,000-8,000 J, Rb,Ra PRE 12,000-10,000 GSL,CS, BS8J WILTON LATE GLACIAL BSL Damp >16,000 .Oxi.Horizon- 3- UNNAMED Wet >18,000 . ....:: YSL LSA Cold? - - - UPPER - G 2 _ Seasonally Wet PLENIGLACIAL I------Oxi.Horizon 2Cod --- GL II MSA? Cold?

Temperate or Rubble Horizon Warm, INTER- Dry PLENIGLACIAL

.';.. Wet D ,..I .::1:. Oxi.Horizon 1 BL Ill ~~~~~Cold,but ~~~~~~Warming LOWER BL II Very Cold PLENIGLACIAL BL I Cold

? TRANSGRESSION

EARLYGLACIAL - -

------Temperate or ------_ Pale Brown Warm, Loam Damp ?40, 000 ?--

10m BEACH

Basal Loam ~~Temperate, Basal~~oam Damp Uj INTERGLACIAL

Notch Cutting and Erosion 15-20m BEACH of Cave

108

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions H/G and BSBB/I, c. 6000 B.P. This is demonstrated geological verificationof the growing body of radio- by marked decalcification,leaching, an increase in carbon data to the effect that the Middle Stone Age organic matter and, above all, by high phosphate extends back to beyond 50000 B.P. (Vogel & Marais levels. 1971; Vogel 1970; Klein 1970; John Wymer, pers. (d) The unleached shell middens all have a low comm.). In fact, the beginningsof the MSA can now density and include little mineral sediment. That be demonstratedduring the last, i.e. Eem Interglacial, component which is smaller than 2 mnmin size so that the earliest MSA appearsto be at least 50 000 already includes 55-65 per cent calcium carbonate years older than it was assumed to be in the mid- and for bulk samples the non-carbonate residue 1960s. In other words, the roots of the MSA are no appearsto average between 10 and 20 per cent. This younger than those of the European Mousterian, implies that a metre of loose, organic midden ulti- although the South African MSA may have persisted mately weathers and compacts to no more than somewhat longer. 20 per cent residue by mass and possibly to as little as 5 cm in thickness. Acknowledgements Although comparativedetails are beyond the scope Field and laboratory work were supported by of this the conclusions are paper, sedimentological National Science Foundation (Washington, D.C.) complemented and find corroboration in the by grant GS-3013 (to R. G. Klein and K. W. Butzer). biological record of the cave with strata, beginning D. M. Helgren (Chicago) collaborated in the field the Yellow Stony Loam: mammalian faunas (Klein during the 1970 season and, together with John 1972b),fish and mollusca (Klein 1972a), and oxygen Piccininni(Chicago), assisted in the sedimentological isotopic temperatureson mollusca (N. J. Schackleton, analysescarried out in the Paleo-EcologyLaboratory pers. comm.). of the Universityof Chicago. Furtherdeterminations Stratigraphicand PaleoclimaticConclusions by the University of Wisconsin Departmentof Soils were made possible through the courtesy of The previous information can now be integrated E. E. Schulte. H. J. Deacon (Stellenbosch) into a broaderscheme of cave evolution time providedvalua- through ble critical comments on a preliminary and in responseto differentclimatic A tenta- draft of the settings. manuscript,while John Rogers tive attempt in this direction is made in figure 4. (CapeTown) provided discussion in the field. The diagramswere The external time-stratigraphicframework of the drawn by ChristopherMueller-Wille. correlationcolumn is adaptedfrom Van der Hammen et al. (1967). It must be emphasizedthat a synthetic chart of this type is an author's interpretationof the References best of the available hypotheses. In this particular BUTZER,K. W. 1971. Environmentand archeology: instance the major weaknesseslie in (a) the lack of an ecological approach to prehistory. Chicago: detailed radiocarbon resolution of the strata older Aldine-Atherton; London: Methuen. than 20 000 years, and (b) the uncertaintiesof internal . 1973a. Spring sediments from the Acheulian and external correlations for the Basal and Pale site of Amanzi (Uitenhage District, South Brown Loams. Consequently,apart from the Rubble Africa). Quarternaria16: in press. Horizon, next to nothing is known about intervals . 1973b A provisionalinterpretation of the sedi- of non-deposition prior to the Yellow Stony Loam. mentary sequence from Montagu Cave (Cape It is equally important to note that stratigraphic Province), South Africa. In C. M. Keller, resolution prior to the Black Loam is minimal. Archaeologyof MontaguCave. Univ. Calif. Publ. Despite these reservations, the Nelson Bay Cave Arch: in press. sequence provides a remarkablycomplete record of DEACON,H. J. 1969.Melkhoutboom Cave, Alexandria the Upper Pleistoceneand Holocene, yieldingvaluable District, Cape Province, a report on the 1967 information on microclimatic variation and, by investigation.Ann. Cape Prov. Mus. Nat. Hist. implication, for external environmental change as 6: 141-69. well. Together with the sedimentarysequences from BUTZER,K. W. & HELGREN, D. M. 1972. Late Ceno- Amanzi Springs (Butzer 1973a), Montagu Cave zoic evolution of the Cape coast betweenKnysna (Butzer 1973b), Klasies River Mouth (Butzer, in and Cape St. Francis, South Africa. Quaternary preparation),and Hoffman'sCave (Butzer& Helgren Research2: 143-169. 1972), the Nelson Bay Cave profile contributes Climateof South Africa. 1954. Part I: Climate statis- towards an understandingof the mid to late Quater- tics. Pretoria: South African Weather Bureau. nary records of man and his environment in the EVANS, I. S. 1970 Salt crystallization and rock southern and south-easternCape Province. Perhaps weathering: a review. Rev. Giomorph.dyn. 19: the most striking implication at the moment is the 153-77.

<- Fig. 4. A tentative Stratigraphicand PaleoclimaticInterpretation of Nelson Bay Cave. Time-stratigraphic units after Van der Hammen et al. (1967). 109

This content downloaded from 128.62.59.252 on Fri, 13 Mar 2015 20:58:19 UTC All use subject to JSTOR Terms and Conditions FAIRHALL,A. W. & Young, A. W. 1973. Radio- PAYNE, T. G. 1942. Stratigraphicalanalysis and carbon dates from Nelson Bay Cave. S. Afr. environmentalreconstruction. Bull. Amer.Assoc. Archeol.Bull. 28. Petrol Geol. 26: 1697,-770. INSKEEP,R. R. 1965. University of Cape Town ROGERS,J. 1966. Thegeology of Robberg,Plettenberg excavations at PlettenbergBay. Scientific South Bay. Unpubl. Honours Project, University of Africa 2: 575-7. Cape Town. KLEIN,R. G. 1970. Problems in the study of the VAN DERHAMMEN, T., MAARLEVELD,G. C., VOGEL, Middle Stone Age of South Africa. S. Afr. Archaeol. Bull. 25: 127-35. J. C. & ZAGWIJN,W. H. 1967. Stratigraphy, . 1972a Preliminaryreport on the 1970 climatic succession and radiocarbon dating of excava- the Last tions at Nelson Bay Cave Glacial in the Netherlands. Geol. (, 46: 79-95. South Africa). Palaeoecology of Africa 6: Mijnbouw 177-208. VOGEL,J. C. 1970. Groningenradiocarbon dates IX. . 1972b. The late Quaternarymammalian fauna Radiocarbon14: 444-71. of Nelson Bay Cave (Cape Province, South VOGEL,J. C. & Marais, M. 1971. Pretoria radio- Africa). QuarternaryResearch 2: 135-142. carbon dates I. Radiocarbon.13: 387-94.

REVIEW

Flora of Lesothoby Amy Jacot Guillarmod.Published Take a practicalexample; you find a piece of plaited by Verlag von J. Cramer, , 1971. fibre in association with Later Stone Age artefacts 474 pp. No illustrations.Price in South Africa in the surface layers of a rock shelter, and approx. R50. you subsequently see a Mosotho woman tying up The bulk of this book is a check list of Lesotho headloads of brushwoodwith a similar-lookingfibre flora, but, fortunately for the archaeologistand the rope. You ask what it is made of, and the woman ethnographer,the contents are not limited to this answers,'Leloele'. So you look up Leloele in Guillar- purely taxonomic aspect. In addition to a brief but mod's book and find it could be Crytanthuslutescens comprehensivehistory of Lesotho,with usefulsections or any of a number of Kniphofiaspecies. Unless you on topography, climate, ecology, land tenure and happen to be botanicallyinformed you are probably land usage, there is also a Sotho glossary of plant none the wiser and will have to wait until you can names and an invaluablesection on the uses made of consult C. A. Smith's Common Names of South particularplants with special emphasis on domestic African Plants (Botanical Survey Memoir No. 35, usage. This type of informationis of immensepracti- Government Printer, Pretoria, 1966). You will then cal value to the archaeologist,especially to those con- discover that the plants in question are Ifafa Lily cerned with the Iron and Later Stone Ages of the and Red Hot Poker, which means a little more to highveld areas of southern Africa. The identification most of us. But this is a criticism which is readily of plant remainsin excavations,instead of remaining overcomeby the combineduse of the two books cited. as a dry list appendedto the site report, can be inter- Dr Guillarmodhas made a substantialcontribution preted in human terms; we can reconstruct, with not only to the botany of Lesotho, where some plant relativeconfidence, the seasonaluses of variousplants species are becoming extinct through overgrazing in the diet, in the household, as materials for the and erosion, but also to ethnographyand the record- constructionof artefactsand buildings, or as medici- ing of traditions,which are likewiseundergoing radical nal, spiritual,or decorativeadjuncts to daily living. and rapid changes. We urgently need this sort of There is one snag to the use of this book in the record before it is too late. field; no common names of plants are included. PATRICIAVINNICOMBE

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