Swartkrans: A cave's chronicle of early man

wartkrans ACave's Chronicle of Early Man

c. K.Brain

November 1993 Transvaal Museum Monograph Transvaal Museum Monografie Transvaal Museum, Pretoria

N8 O.

Transvaal Museum, Pretoria 1993

e

First edition, first impressicn Eerste uitgawe, eerste drul- ,_...... •

"""'""

Fig.l0 Vertical south-north sections through the Swartkrans cave, as visualized in 1974 by Brain (1976), showing the suggested stages 01 development 01 the cave. The Outer Cave is shown to have contained a single deposit only, through which solution channels ramify.

Fig.11 Vertical south-north sectlons through the Swartkrans cave, as visualized by Brain (1976), showing suggested stages 01development 01the cave, foHowing the discovery of the Hanging Remnant, and Ihe assurnption that the Lower Bank must exist. The Outer Cave was then assumed to contain deposits o, both Members 1 and 2.

the former 'pink' breccia, but included the basal travertine (Member 1A) and the thin deposil 01 'orange breccía' in Ihe Inner Cave, interbedded between travertine layers (Member 1e). which had been accommodated by further subsidence 01 the Iloor block. Member 2 was undivided bul comprised both the extensive breccia deposit in the Quter Cave as well as the 'stratiñed brown' breccia 01 the Inner Cave. The presence of later deposits was recognized, but they were not formally designated. A sequen ce of suggested stages in the fermation

of the Swartkrans deposits, as visualized at thattime, is shown in Fig. 11 (Brain, 1976). The realization that Member 1 in the Outer Cave represented a Hanging Remnant, stuck to the north wall, led to the search tor its stratigraphic counterpart, the Lower Bankon the cave traer, as described in the Introduction to this volume. This involved the systematic rernoval 01 natural overburden obscuro ing the walls and contents 01 the entire Outer Cave and the excavation 01selected parts of the deposit.

28

SWARTKRANS STRUCTURE & STRATIGRAPHY

THE CURRENT INTERPRETATION OF SWARTKRANS,. STRATIGRAPHY A plan of the Swartkrans cave, with the exception of lhe Lower Cave, but indicating the position of the Hangíng Remnant ís shown in Fig. 12. Also visible is the permanent metal grid thal has be en erected oVer the main excavation area (see also Fig. 13). Since Ihe time 01 the formal recognition of Members 1 and 2. lhe excavation has provided further insighls into the complexity of lhe filling, now known to have resulted from repeated cycles 01 deposition and erosion within lhe cave. Al present, five Members are recognized, each separated from ils older counterparts by an erosional discontinuity. There is no question lhat many olher separate deposits have fitled erosional

spaces in the Swartkrans cave fill during its 1,7-million-year history, but lhese have been lost by erosion or mining. The importanl point is that the Swartkrans cave has funclioned as a sediment trap, by virtue of its slructure, with openings lo the surface tlbove and olhers leading downwards to lower caverns. Under the inlluence of alternating ciimatic cycles, almosl certainly of a worldwide glaciaJ-interglacial nature, episodes of deposition in the Swartkrans cave have been followed bythose of erosion, creating a depositional mosaic 01 considerable complexity. It now appears lhat Members 1 and 2 occupied much of the GUler Cave, soulh of lhe Hanging Remnant, but the positions in which Members 3, 4 and 5 have been found are indicated in Fig. 14. A vertical section through lhe filling 01 lhe Guler Cave, as it is currently visible, is shown in Fig. 15.

Fig.12 A plan 01 the Inner and Outercaves al Swartkrans, as currently exposed, showing the position 01 the Hanging Remnant 01 Member 1, and the permanent excavation grid.

smMl

hanging remnan!

N

1 o

5

t:-=::.::J

m

Fig.13 An overview 01 the .Swartkrans cave, laken Irom aboye the north wall, looking soulh over the permanent excavalion grid.

29

SWARTKRANS STRUCTURE & STRATIGRAPHY

Fig.14

[:+./\1 Member

A plan 01 the Swartkrans cave, as currently exposed, showing the positions 01 lnñllinqs desiqnated Members 3, 4 and 5.

f.;:·.:.~

Member 4

•

Member 3

N

1 o1 _ . 15 m

Fig.15

s

SECTION A - B

N

A vertical sectlon running northsouth through the filHng of the Outer Cave, as it ls currentty visible, alonq the secticn line as shown in Fig. 12.

~MEMBERI

~ LowerBank

~!;fl~§.1 TRAVERTINE _ MEMBER4 M5A Unit

t:::·:::·:l

MEMBER 2

~

DOLOMITE

o IlwwI

5

.....

6 """"

SWARTKRANS STRUCTURE & STRATIGRAPHV

30

SUGGESTEO STAGES IN THE fORMATION Of THE . CAVE ANO ITS OEPOSITS

OOlOMITE WATER

The suggested formational staqes 01the cave and its contents are presentad as a series 01 reconstructed and somewhat generalized sections (Figs 16-24) running diagonally acrcss the cave trorn the southeast to the northwest corners. Many 01 the features described in these suggested stagas can be seen by visitors lo Ihe site and, fer the benelil 01 such people, a reute leading past 25 points 01interest has recently been constructed, while details 01what can be seen are given in an illustrated guide (Brain and Watson, 1992),

TRAVERTINE

MEMBER 1 Lower Bank MEMBER 1 Hanging Remoant MEMBER 2 MEMBER 3 STRATIFIED MEMBER 2

Fig. 16. Slage 1. A cavern has been dissolved in the dolomitic country rack at a considerable depth below the surlace, in the phreatic zone, below the level 01 standing water. lts form has been determined by joints and planes ot weakness in the dolomite. lt has connections to lower caverns and the tloor ot the main cavern ls strewn with dolomite blocks. The age of the cavern íe probably Miocene.

NW

SE

~'Nr:~_~--~=---:;

_;

~

-=-.'""""'

__

~r:o~ ~ ..~~--"=~ -. - "'=~~-_ ~--=:.....: ==-= ~~ ~ =---=::-:ra...= -: ......-:.-..,¡;:~ -:;-=..;: _ ~;::i:>lOo.:: •~ _

-_...:lIo:

'it..::=u:--_

f-r.l--T::-:o..;

=-w-

~

......:.-=-.:.

~ -......

=->o.::oo....~ .

:-r-:

.

~=-_-....:~-d!J.

:o.:: ~ :-:-= ~ -:::-ir...:: - - ....:: ~~"""~-:..:; _ =--~..=o.....:-----=-=--=-~ _

=-=-

""",..::lo V>

>

--j

O

>

-n

m

--j

Jl

>

m

z

o

--j

ce

-J

I \

)

/

NORTH

I

I

I

i I

I

MEMBER 3

I

'c

\.

°,-1..,1"'1 I I 1/ + I I I Ji< I I I 1;0

'1 1 1 I 1 1 I 1 1 1 1 1 1 I I

I

654321~123

EAST

O

I

¡-¡

l' ¡-¡

N

¡

.m

¡,

! 12

B. DEPTH PROFILE - TOTAL N= 77

83);

."

oo,

'"

'''E:

I

,

A. Plan of Swartkrans cave showing the Member 3 gully, the permanent grid, the number 01 artefacts in each grid square and the depth ranges over which these occurred. B. Profite te show oeprbs below datum at wrucn all moneo Member 3 artefacts were found.

Flg.7

A. GRID SQUARE DISTRIBUTlON

SWARTKRANS MEMBER 3 ARTEFACT DISTRIBUTlON

I

(

I

f f I

/

z

.., '"

m

Gl

>-

lE

tn m ;;:

i\;

>o --
--< m

m

'"b

180

STONE ARTEFACT ASSEMBLAGES

o

¡ 6CM

Fig.8 Artefacts from Member 1 Lower Bank, 1. Casual ccre on a sub-anqular, elongate quartzite cobble showing bipolar flaking. one large cortex ñake (Type 1) and two subslciary tlakes removed from tne distal end. opposed to severa! small scars and crushing al the proximal end. Condilion: fresh. Dlmensicns: 121 x SS x 40 mm. Catalogue no.: SKX 12098, Grid reterence: E2/N4. Oepth: 550-560 cm. 2. Casual care on a sub-anquiar quartzite cobble shcwinq oipotar tlakínq. A single tarqe cortex flake (Type 1) has been removed from the distal end. Opposed at the proximal end on the same tace are severa! smaJl üake scars and crushing. ccndmon. fresh. Dímensions: 78 x 66 x 52 mm. Catalogue no.: SKX 9905. Grid reterence: E3/N4. Depth; 610-620 cm. In both speclmens the opposed scarring at the proximal end of the cobble rs due te lndirect percussion resulting trom the blow that detached the large cortex tlake.

181

STONE ARTEFACT ASSEMBLAGES

i

O

6 CM

Fig.9 Artefacts trom Member 1 Lower Bank. 1. Core/end-chopper on a ñatttsn, angular cobble of chert. bltaciauy ñaked al the distal eno lo remcve severa! small flakes trom both faces, and two parallel flakes and crushing on the right proximal edge. Condition: fluvially abraded. Dimensions: 73 x 63 x 37 mm. Catalogue no.: SKX 13408. Grid reterence: E2/N5. Oepth: 490-500 cm. 2. Polyhedron on a weathered nodule ot quartz, multi-taceted with tndícaticns 01bilateral flaking. Condition: tresh toslightlyabraded. Dimensions: 76 x 73 x 69 mm. Catalogue no.: SKX 7111. Grid referenee: E5JN4. Oepth: 530-540 cm.

182

STONE ARTEFACT ASSEMBLAGES

2

I O

i

4CM

Fig.10 Artefacts Irom Member 1 Lower Bank. 1. Sice-ñake fragment of chert with concave, scraper-Hke retouch. Ccndition: fresh. Dimensicns: 33 x 59}( 13 mm. Catalogue no.: SKX 14822. Grid reterence: E4/N4. Oepth: 690-700 cm. 2. Flat chunk ot quartz with two steeply retouched scraper edges. Condition: fresh. Dimensions: 55 x 44 x 15 mm. Catalogue no.: SKX 21334. Grid reterence: ES/54. Oepth; 220-230 cm. 3. Modified flake fragment of chert with ñat, lnverse llaking on the lett lateral edge. Condition: tresn. Dimensione: 62 x 67 x 24. Catalogue no .. SKX 4103. Grid reterence: E4/N6. Dapth: 660-670 cm. 4. Cortex flake fragment 01 quartz with retouched/modified right lateral edge. Condilion: fresh. Dimensions: 37 x 35 x 10 mm. Catalogue no.: SKX 14427. Grid reterence: E4/N3. Depth: 590-600 cm. 5. Flake of quartzüe with point platform, distally snapped and with inverse marginal modification of the right lateral edge. Condition: fresh. Dimensions: 40 x 34 x 10 mm. Catalogue no.: SKX 16241. Grid reference E4/55. Oepth: 190-200 cm. 6. Small flake fragment of quartz with dorsal modification ot the right lateral edqe. Condition: lresh. Oimensions: 18 x 16 x 10 mm. Catalogue no.: SKX 21306. Grid reterence: ES/54. 230-240 cm. 7. Flake fragmentof quartz with distal modification on the dorsal face. Condition: fresh. Dimensione: 22 x 12 x 10 mm. Catalogue no.: SKX 13244. Grid reterence: E4/N4. Depth 590-600 cm. 8. Small chunkof quartz aüemately flaked to form a beco Condition: tresh. Dimensions: 19 x 17 x 9 mm. Catalogue no.: SKX 13283. Grid reference: E4/N4. Depth: 580-·590 cm.

STONE ARTEFACT ASSEMBLAGES

183

o

i

4CM

Fig.11 Artefacts Irom Member 1 Lower Bank. 1. End-struek. eortex (Type 1) flake 01 chert. Condition: fresh. Dimensicns: 97 x 55 x 21 mm. Catalogue no.: SKX 8692. Grid reterence: E4/N5. Depth: 680-690 cm. 2. Small, side-struck cortex ñake (Type 1) of quartz with ínverse distal modíñcatton. Candition: fresh. Dimensions: 20 x 23 x S mm. Catalogue no.: SKX 8165. Grid reterence: E5/N4. Oepth: 650-680 cm. 3. End-struck flake (Type 6) 01 chert with plain platform and unfcñrecttonat dorsal flaking. Ccndüion: tresn. Dimensicns: 38 x 24 x 9 mm. Catalogue no.: SKX 6199. Grid reterence: E2/N4. Depth: 550-560 cm. 4. End-struck Ilake (Type 6) of quartz with a dihedral platform, semi-corte of perccss.cn aeo right, in verse modification. Condition: fresh. Dlmensions: 58 x 34 x 18 mm. Catalogue nc.: SKX 5601. Grid reterence: E4fN5. Depth: 620-630 cm. 5. Hinged, end-struck cortex flake (Fype 4) ot quartzite, with a plaln striking p'atform and distar. marginal mocññcanon. Condition: slightly aoradec. Oimenslons: 31 x 29 x 10 mm. Catalogue no.: SKX 14030. Grid reference: E4/NS. Depth: 520-530 cm. 6. Hinged, side-struck flake (Type 5) ot quartzite with a point prattorm. Condition: fresh Oimenslcns: 42 x 51 x 14 mm. Catalogue no.: SKX 9535. Grid reference: E2/N2. Depth: 350-360 cm. 7-8. Angular chunks ot chert with coneave spalling suggestive ot thermal fracture. Condítion: tresn. Dlmenslons: 41 x 37 x 20 mm and 37 x 26 x 12 mm Catalogue nos: SKX 21039 and SKX 7018. Grid reterences: E5/S5 and E4/N4. Oeptns: 180-190 cm and 730-740 cm.

184

STONE ARTEFACT ASSEMBLAGES

1 O

1

6~

Fig.12 Artefacts from Member 2. 1. Sub-spheroid of quartz. CondiUon: tresh. Dimensions: 74 x 64 x 59 mm. Catalogue no.: SKX 2101. No provenance. 2. Sub-spheroid of quart: Oondition: lresh to slighUy abraded. Dlmensions: 103 x 102 x 89 mm. Catalogue no.: SKX 19621. Grid reference: W2/S2. Oepth: 170-180 crr

STONE AATEFACT ASSEMSLAGES

.'

185

,.

,':··{:':\W\V\ .:~

¡

o

Fig.13 Artefacts from Member 2. 1. Large cobble end-tlake (Type 3) 01quartzfte with inclined cortex plattorm. Condition: fresh. Dimensions: 91 x 87 x 23 mm. Catalogue no.: SKX 1650. Grid referenee: E6/N4. Depth: 160-170 cm. 2. Large cobble slde-tlake (Type 4) 01 quartzite with plam striking pJatform and sorne right lateral edge mcdfication on the dorsal face. Ccno'ñon: fresh. Dimensions: 95 x 105 x 42 mm. Catalogue no.: SKX 2367. Grid referenee: Ea/Nl. Depth: 90-100 cm. 3. Larqe, thick, end-struck flake (Type 1) of quartzite with cortex prattorrn and semi-cone 01 percussicn. Circumlerence en ventral face shows four radial flake scars suggesting modificatían lar use as a naturally hqh-backed. radially struck coreo Condüion: tresh. Dimensions: 130 x 117 x 65 mm. Catalogue no.: SKX 2159. Grid reference: E4/N1. Depth: 70-80 cm.

STONE ARTEFACT ASSEM8LAGES

186

i

o

6 CM

".

......

~ :".~

.

~.u·

\- ,

-,

I

\

\ \

\

~

-,

,