Last interglacial sea levels and coastal caves in the Cape Province, south Africa

QUATERNARY RESEARCH 25, 189- 198 (1986)

Last Interglacial Sea Levels and Coastal Caves in the Cape Province, South Africa

Q. B. HENDEY

South African Museum, P.O. Box 61. Cape Town, 8000 South Africa

AND

T.P. VOLMAN

Intercollege Program in Archaeology, 265 McGraw Hall, Cornell University. Ithaca, New York 14853

Received June 3, 1985

The dating of the 6 to 8-m shoreline in southern Africa as early Pleistocene prompted a reassess- ment of evidence from archaeological cave sites on the south coast of the Cape Province which had suggested that this shoreline is of last interglacial age. The successions in the caves at Klasies River Mouth and Die Kelders have been misinterpreted. In fact, they confirm a pre-last interglacial age for this feature. These sites, together with Herolds Bay Cave, indicate that in southern Africa the only last interglacial shoreline above present sea level is at about 4 m. and that it dates from isotope substage se. 0 1986 University of Washington.

INTRODUCTION

The Quaternary sea levels of southern Africa have been studied as intensively and are as controversial as those in other parts of the world. Only recently has there been a measure of agreement on the magnitude and timing of the sea-level changes that occurred during the late Pleistocene and Ho- locene (i.e., last interglaciation to the present; isotope stages 5 to 1) (e.g., Hobday and Orme, 1975; Tankard, 1976a; Barwis and Tankard, 1983). Perhaps the most widely accepted opinion is that during isotope substage 5e of the last (Eemian or Sangamonian) interglaciation the sea was about 6-8 m above its present level. This elevation is consistent with the 2 to 7-m limits set for the sea level of this period on the basis of evidence elsewhere in the world (CLIMAP Project Members, 1984). The correspondence between the local and global records indicates that the southern African coastline has been tectonically stable at least since the period of the 6 to g-m-high sea level. The belief that local sea

levels during substages 5a and 5c were at and slightly above present sea level (e.g., Tankard, 1976a) is less convincing, since it is inconsistent with the global record indicating sea levels of 8-20 m below that of the present [see Hails et al. (1984) for references]. This inconsistency has tended to be dismissed without comment, but it requires an explanation. Clearly, it cannot be due to local tectonic uplift since, had such uplift occurred, the earlier 5e shoreline would not have remained close to the global limits.

The solution to this problem emerged during a study of past sea-level changes in the Saldanha region of the Cape Province (Fig. 1; Hendey and Cooke, 1985). This study revealed that the 6 to 8-m shoreline in southern Africa is far older than had hitherto been supposed, dating back to an early Pleistocene interglaciation, with an age in the order of 1- 1.5 myr. Hendey and Cooke (1985) also concluded that there is only one last interglacial shoreline, at about 4 m, that is above present sea level. Al- though there is no direct evidence from the Saldanha region that relates the latter shore-

189 0033-5894186 $3.00 Copyright 0 1986 by the University of Washington. All rights of reproduction m any form reserved

190 HENDEYANDVOLMAN

Ella Province

km -35

- 33

20

FIG. 1. Approximate locations of the southern Af- rican regions and archaeological sites mentioned in the text.

line to a particular substage of the last interglaciation, it is assigned to 5e partly because its elevation falls within the global limits cited above, and partly because the local shorelines are unaffected by tec- tonism and 5e was the only substage when global sea level was higher than that of the present. In addition, evidence from archaeological cave sites on the southern Cape coast, notably at Klasies River Mouth, supports the correlation of the 4-m shoreline with substage 5e. The southern Cape record was mentioned in passing by Hendey and Cooke (1985), and is discussed in more detail below. We first, however, re- view the evidence indicating an early Pleis- tocene age for the 6 to 8-m shoreline.

THE 6 TO 8-m SHORELINE IN SOUTHERN AFRICA

A past high sea level of about 6-8 m above that of the present is recorded at many places along the coast of southern Africa, south of 25”s. It is represented by a variety of features and deposits that suggest the sea-level event concerned was one

of the longer of the Quaternary high stands. The record of the 6 to 8-m sea includes the sedimentary succession that makes up the Port Durnford Formation in Zululand (Hobday and Jackson, 1979), wave-cut platforms and caves in Natal and the southern Cape (e.g., Maud, 1968; Singer and Wymer, 1982), coastal dune complexes in the southwestern Cape (Hendey and Cooke, 1985), and diamondiferous marine sediments along the coast of Namaqualand and southern Namibia (e.g., Hallam, 1964; Carrington and Kensley, 1969) (Fig. 1). Al- though it undoubtedly dates from the Pleis- tocene, opinions on the age of the 6 to 8-m shoreline varied until the original study of the Port Durnford Formation by Hobday and Orme (1975), after which it almost in- variably was referred to the last interglaciation, and more particularly to substage 5e (e.g., Tankard, 1976b).

This dating was first contradicted by Corvinus (1983), who assigned a middle Pleistocene age (ca. 400,000-700,000 yr) to the 6 to 8-m “C Beach” in southern Na- mibia on the basis of its association with Acheulean artifacts. Corvinus also claimed a middle Pleistocene age for the 4-m “B Beach,” and correlated it with isotope stage 7 (ca. 200,000 yr), because she believed it was overlain by final Acheulean and early Middle Stone Age (MSA) artifacts that antedated the last interglaciation. It is evident from her discussions, however, that only a few unequivocally Acheu- lean pieces are involved-none in clear primary association with the “B Beach” or younger deposits. There are also no com- pelling reasons why any MSA occurrences overlying the 4-m beach, and thus the beach itself, antedate the last interglaciation. That a pre-last interglacial age does apply in the case of the “C Beach” seems to be beyond dispute.

Support for Corvinus’ (1983) opinion came from the study of a skull belonging to an extinct bushpig, Kolpochoerus paiceae, found in a consolidated coastal dune at Skurwerug near Saldanha (Hendey and

SOUTH AFRICAN SEA LEVEL 191

Cooke, 1985). The Skurwerug dune complex was developed adjacent to the 6 to 8-m shoreline, and the K. paiceae skull was in- corporated in the dune either while it was being built up or after its formation. An earlier study of deposits in the area revealed that the Skurwerug dune cannot date from the Pliocene (Hendey, 1981a, 198lb), and since the K. paiceae specimen is more primitive than the middle Pleisto- cene variety of this species from the nearby fossil site at Elandsfontein, and since it most closely resembles 1 to 2-myr K. lim- n&es from East Africa in terms of its evolutionary development, an early Pleisto- cene date for the Skurwerug dune and the 6 to 8-m shoreline was concluded. Although this is somewhat earlier than the 400,000- 700,000 yr suggested by Corvinus (1983), the latter is simply a minimum age and therefore not inconsistent with the estimate based on the Skurwerug evidence.

Because both estimates are appreciably earlier than the widely accepted 125,000 yr (substage Se) date for the 6 to 8-m shoreline, the evidence for the latter date was reexamined, starting with that relating to the Port Durnford Formation. It transpired that a curious lapse in logic was included in the otherwise impeccable study of these deposits by Hobday and Orme (1975). The lowermost unit of the Port Durnford For- mation contains a vertebrate fauna long re- garded as being of middle Pleistocene age (Du Toit, 1954; Cooke, 1963), yet Hobday and Orme (1975) chose not to accept this as direct evidence for the age of the formation, but simply to regard it as the lower age limit of the deposits. They then referred to an “Acheulian artefact” that was “probably derived” from the formation, and to a “Sangoan hand-axe” from the sur- face of the deposits, and concluded that these specimens indicated a “middle Upper Pleistocene” upper age limit for the formation (Hobday and Orme, 1975, p. 148). The deposits then were dated to the interval between the lower and upper age limits, and a last interglacial age was pro-

posed based on the correspondence between the 8-m sea level in Zululand and the elevation of the last interglacial sea-level maximum on similarly stable coasts elsewhere.

The archaeological evidence for the upper age limit of the Port Durnford For- mation is unacceptable for a variety of reasons. First, a “middle Upper Pleisto- cene” upper age limit for the Acheulean and Sangoan industries is no longer accepted, and a late middle Pleistocene age applies instead Wolman, 1984). Second, the “Acheulian artefact” may be neither Acheulean nor an artifact, and its association with the Port Durnford Formation deposits is uncertain because it was found below sea level “among many pebbles loose on marine beds” of this formation (Davies, 1970, p. 412, Fig. 11). Similar un- certainties exist in respect to the Sangoan handaxe. an artifact neither figured nor de- scribed. In determining the age of the Port Durnford Formation, there is no need, in fact, for the equivocal archaeological evidence to be taken into consideration, but even if it is accepted at face value it does no more than confirm the pre-last interglacial age indicated by the mammalian fossils found within the deposits. A reexamination of these fossils, which include a previously undescribed Kolpochoerus tooth, con- firmed earlier views that they are no younger than middle Pleistocene (Hendey and Cooke, 1985). Indeed, it is likely that this fauna is older than previous studies have indicated. The Kolpochoerus tooth is particularly significant in this respect, since it is in a comparable evolutionary state to corresponding teeth in the Skurwerug K. paiceae skull. This therefore suggests the Skurwerug dune and the Port Durnford Formation are at least broadly contempo- raneous. Other elements in the fauna are consistent with this conclusion.

The evidence for the age of the 6 to 8-m shoreline from other occurrences mentioned by Hendey and Cooke (1985) supports the contention that this shoreline an-

192 HENDEY AND VOLMAN

tedates the last interglaciation, although it does not prove that it dates back to the early Pleistocene. For example, middle Pleistocene fossils and Acheulean artifacts found, respectively, at Duinefontein and Bok Baai north of Cape Town postdate this shoreline and prove that it can be no younger than late middle Pleistocene.

The record of sea-level changes at Klasies River Mouth and other cave sites on the Cape south coast are now examined in more detail.

KLASIES RIVER MOUTH

A series of excavations was made in caves at Klasies River Mouth (KRM) in the Humansdorp district (Fig. 1) nearly 2 de- cades ago, and the results of the ensuing investigations were published recently in a multi-authored monograph (Singer and Wymer, 1982). Although past sea-level changes formed a relatively small part of the KRM study, the importance of this lo- cality to this subject was appreciated. Un- fortunately, the many statements made in this connection include contradictions and inconsistencies that have obscured its true significance.

Early in the monograph, reference is made to the fact that the KRM caves were “evidently cut by wave action” and that “the level of their floors thus relates to high sea levels of the Upper Pleistocene period,” with the floor of Cave 1 (KRM 1) being “about 8 m above the present sea level,” while the higher caves (KRM 2-5) were cut by a sea level of about 20 m (Singer and Wymer, 1982, p. 2). Mention is also made of a lower, 3 to 4-m sea level. In a later discussion on sea levels, there is a statement that the “unique significance of the evidence from KRM is the very strong inference that the earliest occupation is actually contemporary with the 6-8 m sea” (Singer and Wymer, 1982, p. 187). The “earliest occupation” referred to is that by Middle Stone Age I (MSA I) peoples (see Table l), although it is also mentioned that a “few rolled flakes and one rolled handax

TABLE 1. THE MSA INDUSTRIAL SEQUENCE IN CAVE 1 AND SHELTER 1A AT KLASIES RIVER MOUTH (AFTER

SINGERAND WYMER, 1982, P. 27)

Representation by layer

Industrial stage Cave 1 Shelter 1A

MSA IV 13 - MSA III - l-9 HOWIESON’S

POORT - MSA II 14 (rubble layerp

15 16 (rubble Iaye@ 17a 17b (rubble layer)0

10-21

22-36

MSA I 37-40 -

a The “rubble” layers of Singer and Wymer (1982, pp. 14, 16) are made up largely of derived materials.

in the beach shingle of the 6-8 m sea may indicate even earlier occupation nearby, when the lower caves were still being cut” (Singer and Wymer, 1982, p. 198). Thus, there was at least some doubt in the minds of the authors as to when the lower caves (KRM 1) were cut, and when the first human occupation occurred. This doubt was shared by Butzer (1982, Table 4.1) who indicated that KRM 1 was “eroded or ye- modeled” (italics added) during the maximum transgression of substage 5e, which he took to be at 7 m. Nevertheless, Singer and Wymer (1982, p. 194) went on to conclude that “the earliest occupation (MSA I) at KRM was on the sand of the 6-8 m beach and apparently contemporary with the sea at this level.” Shackleton, in an ac- companying report (1982) based on an analysis of the oxygen isotope ratios of shells preserved in the KRM sequences concluded that the 6 to 8-m shoreline at KRM dates from substage 5e of the last interglaciation. A correlation between substage 5e and the MSA I occupation is therefore indicated (Shackleton, 1982, Fig. 14.5).

Since there are ionium dates of 98,000 and 110,000 yr for the MSA II occupation (Vogel, J., personal communication), the correlation of substage 5e (ca. 125,000 yr) with the MSA I is reasonable. However,


the opinions that the 6 to 8-m shoreline is contemporary with the MSA I occupation, and that it dates from substage 5e, are re- jected here.

One of the major objections to the above interpretation of the history of KRM 1 during substage 5e is that it implies the si- multaneous cutting of the cave by the 6 to 8-m sea level and its occupation by MSA I peoples. Although Singer and Wymer (1982, pp. 187, 194) ultimately concluded that this had indeed been the case, they had earlier realized the impossibility of the situation and allowed for some regression of the sea before the MSA I occupation (Singer and Wymer, 1982, p. 28). Butzer (1982, Table 4.1) came to a similar conclusion, and dated the MSA I occupation as “late substage 5e to early 5d,” or approxi- mately 5000 yr after the maximum sea level of 5e.

Relevant here is the observation by Singer and Wymer (1982, p. 17) that “enough time had elapsed since the cutting of the cave for substantial stalagmites to form on the bedrock or beach gravel before the initial occupation.” The principal significance of this observation appears to have been overlooked. If Butzer’s interpretation of events is correct, then stalagmites up to a meter in diameter and 2 m high were built up over a period of about 5000 yr, which is highly unlikely given the conditions that governed stalagmite growth at KRM. Butzer (1982, p. 38) himself ad- mitted that “a great stalagmite boss with a relief of 1.3 m below a joint fissure in the ceiling at the entrance to the Rear Chamber [of KRM 11” almost certainly required “tens of thousands of years to develop.” The slow rate of stalagmite growth at KRM is borne out by the relatively small size of stalagmites that developed in KRM 1C during the 80,000 yr or more since this cave was sealed in MSA II times (Singer and Wymer, 1982, p. 25, Pl. 28). The KRM 1C stalagmites are much smaller than the larger ones in KRM 1, in spite of the fact that the dripping water and speleothems of

KRM 1C suggested to Singer and Wymer (1982, p. 25) “that it had always been wet.” Although it would be pointless to guess at the growth period required by the large KRM 1 stalagmites, it is likely to have been far longer than the time available in the scenarios of events suggested by both Singer and Wymer (1982) and Butzer (1982). On the other hand, if the 6 to 8-m sea dates back to the early Pleistocene as the evidence from Skurwerug and elsewhere indicates, then as much as a million years was available for the stalagmite growth. It is worth noting that the rate of stalagmite growth in KRM 1 must have varied in response to conditions that pre- vailed in the cave, and since there were probably periods of little or no growth, the time required for the development of the large stalagmites is more likely to be mea- sured in hundreds of thousands of years than in millennia. The study of a core from one of these stalagmites may yet resolve this issue and perhaps provide a record of temperature changes on the Cape south coast between the early Pleistocene and the last interglaciation.

The large stalagmites in KRM 1 do not necessarily confirm an early Pleistocene age for the 6 to 8-m shoreline. But, coupled with the record of a rolled hand axe in the 6 to 8-m beach deposits of this cave, the stalagmites strongly suggest a pre-last interglacial age does apply. Furthermore, by eliminating the 6 to 8-m-high sea level from the last interglacial record, the KRM I sequence can be more convincingly correlated with the global record of sea-level changes during this interglaciation.

As indicated earlier, the study in the Sal- danha region by Hendey and Cooke (1985) recorded only one sea level, 4 m higher than that of the present, during the last interglaciation. A sea level of about this elevation is also recorded at KRM. According to Singer and Wymer (1982, p. 30) the 4-m sea postdated the MSA IV occupation. whereas Butzer (1982, Table 4.1) correlated it with the MSA II occupation and substage


5c. All these correlations are discounted here, and the 4-m sea level is correlated instead with substage 5e, which in turn may have coincided with the MSA I occupation. During the period of the maximum 5e transgression, the shoreline would then have been seaward of KRM 1, abutting the low cliff at the southern end of Section S in East Cutting (Singer and Wymer, 1982, Figs. 2.1, 3.1A, and 3.6), rather than being in the cave had it been the 6 to 8-m sea that was of 5e age. The MSA I occupation of KRM 1 during substage 5e, as indicated by Shackleton (1982), therefore would have been possible, although storm waves may still have rendered the cave uncomfortable, if not uninhabitable. Such storm waves also may have been responsible for scouring the cave of much of the deposit that had accu- mulated there earlier. Thus, the MSA I occupation may have commenced after the maximum transgression of substage 5e, as indicated by Butzer (1982). This would agree with the evidence of the molluscan fauna associated with the MSA I occupation, which suggests accumulation during a period of “cooling” (Voigt, 1982, p. 165). The MSA I mammalian fauna also suggests accumulation during a cool period, pos- sibly early substage 5d (Klein, 1976, 1983).

The correlation of the MSA II-IV and Howieson’s Poort occupations at KRM with past sea levels is even more subjec- tive. However, since marine resources continued to be exploited throughout these occupations, the shorelines must always have been within reach of KRM (Klein, 1976), a situation that almost certainly ap- plied during the remainder of the last interglaciation. This was particularly likely during substages 5c and 5a, when global sea levels were no more than 20 m below that of the present. Even during substages 5d and 5b, the shorelines probably were not far away, because the off-shore topography is such that even with a regression of as much as 50 m “the littoral environment would have been less than 5 km distant” (Butzer, 1982, p. 39). Perhaps all that can be safely concluded at this stage is that the

MSA I-IV and Howieson’s Poort occupations at KRM were largely, or entirely, confined to the last interglaciation.

A problematical aspect of the KRM sequence concerns the mode of deposition of the “rubble” layers in KRM 1 (Table 1). They are exemplified by layer 14, a chaotic conglomerate comprised of “beach pebbles and boulders, lumps of calcite, broken stalagmites and stalactites, and fragments of rock wall” in a sand and silt matrix (Singer and Wymer, 1982, p. 17). Although layer 14 contains abundant bones and MSA I1 artifacts, there are no hearths or stratification, and it is clearly not an in situ human occupation deposit. Singer and Wymer (1982) believed that layer 14, together with layers 16 and 17b in KRM 1, was formed by materials rolling down the slope of a large mound of occupational debris that had built up outside the mouth of the cave. On the other hand, Butzer (1982, p. 38) concluded that layer 14 was a storm beach deposit associated with the 4-m-high sea level, perhaps reflecting “once-a-year events” or “one-in-ten-year storms” over a period of a few millennia. The latter interpretation is the less likely of the two alternatives, since it is unlikely that any of layer 15 and other underlying horizons would have survived the repeated storms visualized by Butzer. Furthermore, layer 14 would have included MSA I artifacts derived from the underlying deposits eroded near the mouth of the cave by the storm waves, and apparently this is not the case. In view of the earlier conclusion that the 4-m sea level was of substage 5e age, the correlation of this sea level with layer 14 implies that the MSA I occupation preceded the last interglaciation. While this possibility cannot be dismissed, it is not favored here because of the lack of other supporting evidence. If the storm beach hypothesis is correct, layer 14 cannot be of post-substage 5e age, since sea levels then were 8 m or more below that of the present, and storm waves of an impossible height would have been required to deposit layer 14.

Although the explanation by Singer and

SOUTH AFRICAN SEA LEVEL 19.5

Wymer (1982) for the origin of layer 14 is the more plausible, they may have under- stated their case. Rather than materials simply “rolling down the slope” of the mound outside KRM 1, one or more events of catastrophic proportions is envisaged instead. The materials comprising layer 14 had to move more or less horizontally over a distance of at leasl 15 m inside the cave and this, coupled with the chaotic fabric of the deposit, indicates a transporting agent in addition to gravity. Water is the only possibility. Flooding caused by torrential rains would have provided the impetus required to set off a landslide to deposit layer 14 in the form and position in which it was found. A major difficulty with the landslide hypothesis is the presence in the deposits, apparently in substantial numbers, of beach pebbles and cobbles, items generally rare in the KRM occupation horizons. Un- less MSA II peoples had for some reason transported large numbers of beach rocks to the mound outside KRM 1, these materials must have been transported directly into layer 14 from the beach in front of the cave. If the deposition of layer 14 by peri- odic storms is discounted, it leaves only an exceptional occurrence such as a tidal wave that might have been responsible. Singer and Wymer (1982) discounted this possibility on the grounds that there is no other evidence for such an event along the southern Cape coast. The absence of MSA I artifacts from layer 14, as mentioned above, also counts against the tidal wave hypothesis.

While the origin of layer 14 has yet to be satisfactorily explained, its association with a catastrophic event is supported by one of the more unusual discoveries so far recorded in an archaeological cave site in southern Africa-the articulated skeleton of a leopard found “on the edge of the mound of layer 1.5” (Singer and Wymer, 1982, p. 14, Pl. 14). Although this occurrence was recognized as warranting both an illustration and a brief description, apparently its taphonomic significance was not appreciated. The leopard was probably

either resident in KRM 1, or had sought temporary refuge there, and its presence implies that the cave was not occupied by humans at the time of its death. The animal is likely to have died suddenly and it almost certainly was buried soon afterward, since the skeleton was found in a largely undis- turbed state with no signs of postmortem disturbance by either people or animals. Since it was buried against layer 15 by layer 14, this suggests that the materials comprising the latter unit were introduced into the cave suddenly and in bulk, probably resulting in both the death and burial of the leopard. These circumstances are in keeping with both the landslide and tidal wave events postulated above. The former event may again be the more likely, since the violent storm precipitating the landslide may also have caused the leopard to seek shelter in the cave.

Although a 20-m sea level is mentioned by Singer and Wymer (1982) and briefly discussed by Shackleton (1982), it is not relevant to this paper because no one today would maintain a last interglacial age for the 20-m sea in southern Africa. A late Pliocene age (ca. 1.7-2.3 myr) is likely to apply instead (Hendey and Cooke, 1985).

To sum up, there is unequivocal evidence at KRM for only one sea level higher than that of the present during the last interglaciation. This is the 4-m sea level, which is correlated here with isotope substage Se. The 6 to 8-m and 20-m-high sea levels, which cut the KRM lower and upper cave complexes, respectively, antedate the last interglaciation, the former dating from the early Pleistocene and the latter from the late Pliocene. The KRM caves are cur- rently being reinvestigated in a collabora- tive project under the direction of H. J. Deacon, and it is expected that some of the unresolved issues indicated above will re- ceive attention.

The situation at other sea-cut caves along the southern Cape coast is entirely consistent with the preceding scenario of last interglacial sea-level changes. Two ex- amples are examined below.

I96 HENDEY AND VOLMAN

DIE KELDERS At Die Kelders, on the Walker Bay coast

(Fig. l), a cave complex has formed through erosion at the contact, planed lo- cally at 7-8 m above sea level, between Paleozoic sandstone and Cenozoic coastal limestone. Excavations in one of these caves, Die Kelders I (DKI), extended through MSA levels to reach the top of a wave-generated boulder bed at 2 m above sea level (Tankard and Schweitzer, 1974, 1976; Tankard, 1976~). Tankard and Schweitzer (1974, p. 368) placed cave formation during isotope substage 5e, “by a sea 7 to 8 m higher than present at about 120,000 BP, although high sea levels of a previous interglacial may also have con- tributed” (italics added).

Tankard attributed the beach at the base of DKI to the end of the last interglaciation, relating it first to a sea at 2 m above the present (Tankard and Schweitzer, 1974), and then to a sea level equal to the present (Tankard, 1976~). Although Tan- kard (1976b) recognized that sea levels at these elevations were unlikely during the last interglaciation after substage 5e, he did not take this into account in his interpretation of DKI. As a consequence, the MSA sequence at DKI was assigned to the last glaciation and correlated with all or parts of isotope stages 4 and 3 (Tankard and Schweitzer, 1974, 1976; Tankard, 1976~; Klein, 1975; Avery, 1982; Volman, 1984). This dating of the MSA horizons could well be correct, since an unknown amount of time, represented by sterile dune sands, had elapsed between the formation of the beach and the initial MSA occupation. Nonetheless, there is nothing about the MSA artifacts and associated fauna1 re- mains that precludes a last interglacial age for some or all of the MSA horizons at DKI.

If it is unlikely that the beach deposit in DKI dates from the end of the last interglaciation, it is equally improbable that cave formation dates to substage 5e. Butzer (1979) noted that discontinuous flowstones

and stalagmites developed in the caves at Die Kelders after regression of the sea from at least 7 m above present sea level. Breccia accumulation followed and in DKII, adjacent to DKI, a flowstone in a niche above the present floor includes a few quartzite flakes, apparently MSA, along with corroded limestone roofrock. The implication is that both caves, which now contain MSA horizons overlain by Holocene shell middens (Schweitzer, 1979), once were filled with other deposits, including MSA materials in horizons above the present floor in DKII. These deposits are virtually absent now, scoured from the caves by the same sea level that left the beach at the base of DKI.

It is unlikely that the responsible sea level was only 2 m or less above the present one. The mouth of DKI is only 10 m from the shore and Holocene sea-level changes have not affected its deposits. We suggest that the beach deposits at the base of DKI, exposed only in a narrow trench near the cave mouth, were emplaced by the 4-m sea level during isotope substage 5e. We further suggest that the initial cave formation occurred considerably earlier, during the 6 to 8-m sea level of the early Pleistocene.

HEROLDS BAY CAVE At Herolds Bay Cave, near George (Fig.

l), MSA artifacts and occasional shells were cemented into the top of a coarse beach sand at about 5 m above sea level (Deacon, 1979; Brink and Deacon, 1982). The artifacts are comparable to the MSA I pieces at KRM. Overlying dune sands contain similar artifacts in association with hearths and a shell midden. An angular elastic rubble that contains bones accumu- lated by carnivores and porcupines post- dates the human occupation horizons. This in turn is capped by a flowstone with an ionium date of about 80,000 yr (Vogel, J., personal communication). Although the small salvage excavation in Herolds Bay Cave did not reach bedrock, we concur


TABLE 2. LATE CENOZOIC HIGH SEA LEVELS OF SOUTHERN AFRICA<’

Height above present sea level (m)

Age 1.5

Holocene 4

Late Pleistocene (isotope substage Se) 125,000 yr

6-8 20 Early Pleistocene Late Pliocene

0 Adapted from Hendey and Cooke (1985).

with the assessment by Brink and Deacon (1982) that the cave demonstrates the “presence of a 5 m raised beach” (p. 31), and an MSA occupation “towards the be- ginning of the last interglacial” (p. 38).

SUMMARY

The records in archaeological cave sites at Klasies River Mouth (KRM) and Die Kelders (DK) on the south coast of the Cape Province have been interpreted as indicating a high sea level of 6-8 m during isotope substage 5e of the last interglaciation, and sea levels at or above the present level during substages 5c and 5a. These conclusions are contradicted by recent studies in southern Africa which have dem- onstrated that the 6 to 8-m sea level ante- dates the last interglaciation, and the global record of sea-level changes during this period which indicates that on stable coasts the sea was below its present level during substages 5c and 5a.

We conclude that the KRM and DK successions have been misinterpreted, and that in fact they are consistent with the last interglacial sea-level record elsewhere in southern Africa and further afield. These successions actually support the view that the 6 to 8-m sea level in southern Africa is of pre-last interglacial age, although they do not confirm the evidence from elsewhere that this sea level is of early Pleisto- cene age. In addition, coupled with the succession at Herolds Bay Cave, they are significant in suggesting that the 4-m high sea level recorded in southern Africa is of substage 5e age. There is no evidence from these caves that the sea during substages 5c and 5a was at or above the present level.

The Quaternary high sea levels docu-

mented on the basis of the southern Af- rican record are shown in Table 2.

ACKNOWLEDGMENTS

We thank A. L. Bloom (Cornell University). H. J. and J. Deacon (University of Stellenbosch). R. G. Klein (University of Chicago), and N. J. Shackleton (University of Cambridge) for commenting on the manuscript. The research of one of us (Q.B.H.) is supported financially by the South African Council for Scientific and Industrial Research, and this assistance is gratefully acknowledged.

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Documents

Last interglacial sea levels and coastal caves in the Cape Province, south Africa