previous.gif     next.gif    


By Alfred de Grazia

Part Two: Geological Issues



In September 1976, I happened to meet Ofer Bar-Yosef, Ernst Wrestler, and other archeao-anthropologists from Israel on an excursion through the caves of Southwest Aquitaine. There I learned of the work that had been done at Ubeidiya, a location two and a half hours' drive from Jerusalem. Stekelis, who died in 1967, had brought in Louis Leakey to examine the site, and they got the idea that the Olduvai and Ubeidiya remains were closely related. Yet the latter were placed well under a million years while the former was considered a million years older. For sixteen seasons the Israelis had been on the site, but work had been suspended now for two years.

I was impressed; then and now; with the probability that the East African Rift, including Olduvai Gorge, was connected in time with the Dead Sea-Syrian Rift via the Red Sea. Therefore cultural contemporaneity, I ventured to say, had also to be watched for along the whole length of the Rift. My further speculations about the extreme recency of human beginnings along the Rift were mentioned diffidently and heard with some amusement.

In 1983 the Ubeidiya scholars emerged in Nature magazine with a reevaluation of their hominid remains; they redated them to coincide in time with some of the oldest of the African Rift hominids. Having gone this far, I expect that one day they will go farther and will have to claim that all along the Rift, the hominid sites, "oldest" in the world, must be brought up to the Holocene, perhaps only 14,000 years ago. Earlier in the same year, I had been considering the radiometric datings along the Rift and wrote in my journal of my doubts:

March 10, 1976;

Bones of humans are destroyed by weathering, animals, and disasters - fire, flood, hurricane. Bones are preserved by burial in dry tombs or sand, and by dry ash or tuff at low heat.
? All Rift burials and findings are from fall-out or quick wash flood and dry-out (i. e. volcanism or flood.)
Dating by K/ A [Potassium 40-Argon 40] in Rift questionable in re:

Erraticism of some of dates.

Choice of small grains with more argon because more surface ratio to volume and therefore older dates since argon from air contaminates surfaces.

But younger dates may come from escape of argon at near melt temperatures following flow or fallout.

Questionable behavior of potassium.

Averaging may be used questionably.

Fudging and rejection unjustifiably of "impossible" dates; "reasonable" choice is unreasonable.

Superposition over short term can be achieved by an atmospheric condition of initial high argon content which is absorbed by first-laid rocks and then as successive rock layers are laid down (or sediments) the argon in the atmosphere is escaping and therefore less and less proportionally absorbed, giving upon test a gradient of pseudoage from bottom to top in seeming accord with super-positioning.

?? Were accepted test results all reported and all blind, all from same size specimens and sampled by same procedures?

Regardless of age gradient of tests, tests give old readings. Since 0 argon is found on new deposits and some argon on 3000 and 36000 year old (???) deposits, how can it be said that the argon test is inapplicable to under 1,000,000 y? Such tests should be highly erratic.

Is K/ A a test of the amount of argon in atmosphere at time of deposit?

Couldn't argon 40 be exuded from K 40 by earthquake and intruded into volcanic lavas and kept there as these cooled, giving them long ages? Yes.

If "trace elements" rise to the top of the Earth's crust, and if "daughter" concentrations follow suit; if "trace elements" are essential to methods of measuring rock ages; if rocks are igneous; if igneous flow (fissure or cone) proceeds by erupting lavas from the top rock melt layer, then the next to the top layer of melt, et seq., - then, radiodating will show old dates at bottom of the column, and younger dates as measurements move up.

This is as expected and found. But the layering could occur in a very short time set of eruptions and evidence a series of old ages in some kind of proportions because the daughter traces will be most abundant in the lowest samples and decline progressively as the samples are taken from lower in the plasma melt.

Addressing himself to that part of the African-Red Sea Rift which stands on the continent, R. B. McConnell argued a 2.7 billion year age for its beginnings and limits severely the changes of recent times [1] , compares it with the Rhine Graben and Baikal depression. I have linked all three with the simultaneous world rifting or fracturing of only a dozen millennium ago.

With such old dates, McConnell has to confront a general opinion nowadays that the rift system of the oceans (and, by inference and otherwise, land) is no older than 200 million years. Moreover, the great rifts of the world, oceanic and terrestrial, seem to have been in motion as part of a world system. Spreading in widely separated regions show similarities, including correspondences even when discontinuities are compared [2] .

Gregory, an early explorer of the African Rift Valley, dated the vast diatomite deposits of the lakes to the Miocene Period. But Louis Leakey found hand axes embedded in the lake deposits and therefore called them Pleistocene [3] . Olduvai Gorge appears young to the geologist's eye. All of East Africa seems so, too. The Victoria Falls and Zambezi Gorge seem very young. Suppose the Falls to be of the same age as Niagara Falls; this would place a spectacular bit of Africa within reach of 3500 years of age. A quantavolutionary view of geology tends to bring more and more features more and more together; the Earth's surface tends to be hologenetic and is seen in holistic perspective. Olduvai Gorge could have been created during the Bronze Age of Egypt.

Willis speaks of a geologist's (Combe's) knowledge allowing him to tell that pebbles of tin ore found in the Kafu River came from "downstream" instead of upstream, because the course of the river had been reversed as a result of the great rifting.

Since the pebbles could not be of ancient origin, the story bespeaks the recency of the change and of the Rift.

Flint, in his Glacial Geology (p. 523), refers to the Rift as late Pleistocene. S. Cole discusses some of the material in a manner to support skepticism: the near total confusion of climatic periods (52 and chap. 2); the unreliable use of advances and retreats of lake sands to date Rhodesian cultures (53); the great tectonic changes of the Pleistocene; the fact that neither neolithic nor bronze ages have been found in Africa; the astonishing slowness of culture change ( million years of the same hand-stone); the great destruction of mammals notable in Olduvai beds I and II, then separated by "a million years."

She says (113-4) that Olduvai Gorge "assumed its present form, with narrow floor and steep sides, in Post-Pleistocene times, when erosion cut right down into the Pleistocene deposits, thereby exposing the great series of sediments seen today." Erosion, however, does not "cut right down;" Olduvai Gorge split open quickly, hence the "narrow floor and steep sides."

Cole, like L. Leakey and others, have a way of speaking of "people cultures," "industry sites," "living floors," and "living sites" for the hominids, making one wonder whether they had tile floors and awnings. A uniformitarian image is thus purveyed, and one is led to think in terms of extremely gradual sedimentation as creating the scene. Yet the australopithecine (1959) Zinjanthropus' skull "had been broken by expansion and contraction of the bentonitic [i. e. volcanic] clay in which it lay, 22 feet below the top of Bed I, which at this point is about 40 feet thick; but the bones had not been distorted in any away, and even such fragile pieces as the nasals were recovered." (117-8) And she remarks that three or more relatives were found on Floor I and 4 meters away with "a worked bone tool." She surmises that the hominids lived upon the tortoise and catfish of the shallow waters at hand (120-1).

Legbones were found standing upright; this seems impossible, given the undisturbed condition of the clay encasement, unless the long period of "sedimentation" were in fact the ash fall of a single day. "Coarse vertical rootmarkings are common in many of the tuffs..." (III, p. 11). About one-fifth of the strata contain them. They also carry through beds of sediment, evidencing other instants of high production to create the geological column above the earliest hominids. Elsewhere, in Homo Schizo I., I have spoken of the human traits of australopithecus. A perplexed discussion has long centered upon the "people culture" of Leakey's first-found hominids, and much effort has gone into depriving him of his human qualities, to no avail; Australopithecus Bosei was probably the maker of Olduvai implements, of a "two-million year old" circular stone barrier of the lowest level of Bed I [4] , a selective cracker of animal bones, with a "frequency of implemental patterns of behavior" [5] .

Bed II rest conformably upon the older Bed I. Yet "a million years" has passed. Conformity suggests continuity and absence of a gap in time, and an absence of natural catastrophe. But both are evident. The fossil assemblages connote disaster. Groups of mammals and primates or people do not congregate voluntarily to await death. An elephant skeleton without a skull was found. The method and motive for separating the two are found in natural forces. The hominid finds are not nicely segregated by time gaps (see v. III, 229, 234).

Strange to say, a toe bone, possibly human and modern, was found in Upper Bed I (Tuff If), belonging to an "upright, bipedal, hominid possessing a plantigrade propulsive gait." (p. 230). Many years later, modern footprints of a three person-group were found at Laetoli by Mrs. Leakey. These go towards establishing the humanness of australopithecus, or else a most embarrassing confusion of time has occurred, and australopithecus consorted with humans; the latter is possible, if all artifacts were made by beings other than australopithecus.

Dr. B. Willis published in the 1930's two books which treated of the African Rift system. He remarks, as is well-known, upon the foundation rocks exposed throughout East Africa, where they are intruded or covered by volcanic products. Sediment are lacking or thin. He asks, where does the great melting below the surface that lifted the continent come from [6] ? To my way of thinking, the melting came from the immense catastrophic push of the Atlantic Ocean cleavage that moved the African crust eastwards and from an accompanying expansion of the Earth. The plateaus rose. Then the great arch cracked and dropped, forming the Rift valley. Inasmuch as the Atlantic cleavage veered East and shot up a northern branch, and this fracture cut off Madagascar and India from the African continent, the Eastern rim of the new African format could accelerate into the widening basin, and hence an auxiliary fracture, not so deep, the Rift Valley, opened; in effect, it dropped between the steep plateau walls. Volcanic products are everywhere and in all forms, ash, lava, tephra; Olduvai gorge was cut through many strata of volcanic emissions.

Willis writes of meeting Louis Leakey, then of merely local fame, and J. D. Solomon, a colleague, at Lake Elmenteita in 1919. "They even think he [man] may have witnessed the later developments of the rifting to which the valley owes its character. If so, we shall have to change the time scale, either by hurrying geologic processes or by greatly prolonging the stone age of man's evolution" [7] . The latter course has been taken [8] .

Yet since Olduvai Gorge fractured open after hominids and hominoids were already on the land and long buried in the area, the catastrophic event must have been witnessed by humans. Considering the topography, the Gorge is directly connected to the Rift; it is 370 feet deep; about 40 strata are identifiable in some 300 feet of depth, averaging thus about 7 feet per stratum. The fossils are found embedded in the cliffs on both sides of the gorge; the fossil beds are sandwiched between lava flows on both sides; the oldest fossil bed is termed Bed I, the youngest Bed IV.

Alternative possibilities are weak: if the Gorge came first, then hominids of successive ages dug themselves into the cliffs, taking care not to disturb the lower strata as they climbed up to dig into their proper superposition. Or the Gorge may have been a small stream valley, was settled by hominid I, then lava poured over one lip, filled the valley, and covered the opposite rim, while on other occasions, volcanic fall-out layered over the whole, and in both cases the stream washed away the valley deposits; hominid II came in while the stream was cutting away the valley deposits, but then the whole process repeated itself four times until today.

A third possibility is that the area was heavily settled. Then volcanic eruptions brought in ash and lava and caused evacuation of the biosphere, except for rare trapped remains. New settlements occurred, and then by the same means, Bed II occurred and was covered; and so on. Then came the rifting and gradual erosion and exposure. Gradualism contradicts evidence brought out here. And what kind of volcanic system is it, which covers the region but conveniently lays down a blanket every quarter of a million years and is resting in between-times?

By far the most plausible explanation for Olduvai Gorge and its contents is successive, heavy rainfall, floods, lava streams, and ash falls, occurring over a period of a few centuries. Human types moved in and out, chancing sudden destruction and quick burial here as anywhere else. Finally the risen plateau ruptured, Olduvai being a local incident in a global frame. The climate turned dry, the volcanoes became more peaceful, soda springs hissed harmlessly and began to expire, the surviving mammal population gathered near the remaining sources of water, as did the surviving and incoming humans.

To sum up, I would make several points. General quantavolutionary evidence of recent global transformations supports a short-time or microchronic view of Olduvai Gorge and its biosphere outcroppings. Potassium-argon datings support the conventional macrochronism but they are discordant and may be basically flawed. Numerous geological and paleontological indications support microchronism. The recent claim of equal age for rift remains in Israel adds support, although both these and Olduvai remains should be moved up, not back, in time. The Rift, hence the Gorge, split open late enough for human legends to carry down a report of the events.

Notes (Chapter 13: The Latecoming Olduvai Gorge)

1. The reference here may be to a passage from Curtis and Everden, in Louis Leakey, p. 91: "... the few volcanic sanidines of historic age dated by us have yielded ages inconsistent with the concept of zero argon content at the time of eruption. Both the 1912 eruption of Katmai and the 1304 eruption of Ischia yielded zero potassium/ argon ages. Also dates of late or post-Pleistocene event have given reasonable ages. A late Gamblian tuff from Lake Naivasha in Kenya gave 28,000 years and a prehistoric post-glacial pumiceous rhyolite done near Mono Lake, California, gave 5600 years..." However, two paragraphs later, they report a possible 11,000 year feldspar (sanidine) gave them datings of several hundred thousand years.

2. 83 Geol. Soc. Amer. Bull (Sept. 1972), 2549, at 2565.

3. Heirtzler, Dixon, Herron, Pitmann and Le Pichon, "Marine Magnetic Anomalies, Geomagnetic Field Reversals and Motions of the Ocean Floor and Continents," 73 J. Geophysical Res. (1968), 2119-36.

4. Sonia Cole, The Prehistory of E. Africa (London: Weidenfeld and Nicolson, 1964).

5. L. Leakey naively compares his "fort" to those erected by the Okombambi tribe today (vol. III, p. 24), a two-million year old tradition!

6. P. V. Tobias, Olduvai Gorge, vol. 2 (Cambridge U. Press, 1967).

7. Living Africa, 289. And see his East African Plateaus and Rift Valleys (Washington, D. C.: Carnegie Institution, 1936), publ. n 470.

8. Ibid., 270.

9. It is instructive to compare the processes of science that moved toward the acceptance of Olduvai hominids of great age and the rejection of Calaveras man in California, as reported in W. H. Holmes, "Review of the Evidence Relating to Auriferous Gravel Man in California," Annual Report of the Smithsonian Institution, 1898-9, 419-71.


previous.gif     next.gif