Perspectives on the Calico Site


by Louis S.B. Leakey (excerpted from Dr. Leakey’s keynote address at the International Conference on the Calico Mountains Excavations held in San Bernardino, California, October 22-25, 1970)

I want to give you some background thoughts and ideas in connection with the work that’s being carried out at Calico.

First, I want to elaborate briefly on the question of what qualifies as an archaeological site in a geological context. Most of the archaeological sites of the Middle and Lower Pleistocene are sites in a geological context. It is only in recent years that such archaeological sites have been found under conditions more than just in a geological context, but as a living floor. Living floors of those remote periods are few and far between, and when you get one in a geological context, you are very lucky. I would remind you that more than 90% of the archaeological sites of the Middle and Lower Paleolithic of Europe and Africa are not living floors.

Early man had to live near running water, and subsequently the artifacts and the bones that he left behind on the banks of streams and lakes were carried by water action into adjacent river gravels and other fluviatile deposits. Almost all of the early sites of France and England. We seldom have the sites where they actually lived, but you suddenly find a concentration of artifacts in the terrace gravel. The original living site was not far away on the bank, and over the years after the site was abandoned, the artifacts were carried down from the living floor on the bank into the gravels.

That, as I see it, is the position of Calico. We haven’t found where man lived on the fan. Presumably, the fan had water at different points at different times. Water comes down over one part of the fan one year and then shifts slightly to a different part of the fan. The fan was not built up by water deposition alone, but much of it was formed by massive mud flow. The fan deposits are not a great mass of stones that moved down together, but are mixed up with sands and gravels.

Man lived on the then surface of the fan as it was building up, and subsequently, these artifacts, or some of them, got washed down by water action into certain parts of the fan at limited points adjacent to the living floor. In my view, on that ground alone, the Calico excavation is every bit as much an archaeological site as the classic sites; of France and England.

Next I want to discuss briefly the questions of what nature can do and what nature cannot do in simulating human workmanship. I speak on this subject as one who has done a great deal of study on it. Back in 1923 I met Hazeldine Warren and Reid Moir who were concerned over this question of what nature can do. I personally participated in work at various places with both of them.

Nature can simulate humanly-struck flakes with widely diffused bulbs. A site with flakes of this type is found in Darmsden, England. At first I supported Reid Moir in his belief that Darmsden was a site with human culture. But when I went there myself and investigated and excavated, I found evidence which satisfied me that this was not the work of man, because again and again when a cobble was found from which one, two, or three flakes had been knocked off, nearly always you could find the flakes that came off it within a very short distance. The flakes had been knocked off, but not carried far away. Instead they were rather close to the cobbles from which they had been struck.

In the sub-crag deposits where flakes were being pushed off, in the main by earth movements, one found the lumps from which the flakes had been pushed. And there, a short distance away, sometimes even touching it, were the flakes that had come off. Those pressure flakes are very distinctive, and as Hazeldine Warren said in 1923, they cannot be mistaken for human work except by those who do not understand technology.

One gets situations on pebble beaches where, under storm conditions, stones are hurled at each other, and a certain number hit each other in such a way that a flake comes off. But the number is infinitesimal and there is a uniform scatter over a length of beach–not a concentration in a small area with nothing elsewhere.

I want you to realize that in claiming that the artifacts which we have found could not be the work of nature, I have from the beginning taken all these things into consideration. Any one single flake just possibly could be nature made. But they are in a concentration in a limited area, and since they are not found at other places in the fan where we have put down pits, then it is more convincing still.

Finally there is the point that nature is never selective. At places where you get natural flaking, the flakes have been pushed off good material and bad material. A flake from a lump of chert that is riddled with holes and full of irregularities is pushed off by earth pressure, and the resulting flake is, therefore, also full of holes and other irregularities. One of the most striking things about the Calico specimens, even with the cortex flakes, is that, almost without exception, they are not flakes struck off a piece of chert of poor quality. They are flakes struck off a selected piece of chert, or a piece of jasper. There are other materials besides chert and jasper available in that deposit, and mostly they do not have flakes removed from them, except for a few of limestone. This selectivity is something nature never does. Nature splits off flakes at random. Man knocks off flakes for a specific purpose.

The next thing I wish to consider is an important one indeed; that is the problem of age. I have consistently refused to say more about Calico than that it is over 50,000 years old, and I have consistently warned the crew that it might be a great deal more. The safe thing is to say that it is over fifty thousand years beyond the range of carbon dating. I know that there are those who believe the fan is so old that it couldn’t contain artifacts. That I don’t believe, because the artifacts are there! The possibility of a great age should not interfere with the interpretation of facts.

Supposing that this site proves to be infinitely older than 50,000 years, what does it mean? Does it mean that the site is impossible? Can you therefore write off the other evidence? Remember, it is not so long ago we thought the earliest known stone tools in the world were about 500,000 years old. Then we pushed that back and back, and now we have sites, published and accurately documented, at more than 2.6 million, with flakes and stone tools not very different from those here.

There are two questions at Calico, and the two, if they are both true, must fit each other, because truth cannot conflict with truth. The first truth is that you have a fan of very considerable age. It may possibly be of more than one age, but nevertheless, even the younger part of the true fan is not young in terms of American prehistory. One problem that we have to solve is the probable age of that part of the fan that is yielding the artifacts.

The antiquity of the deposits is one fact. The second is that it contains specimens that certainly look as though they are man-made, I don’t think that anyone who sees the total assemblage, or even the representative assemblage I put out for your examination, will not be impressed by the evidence. I suggest that you should consider all the factors and see what it says to you. And I tell you I believe it represents unquestionable evidence that man was living at the time this particular part of the fan was accumulating and being built up.

What this means in the terms of the age of man in the Americas we’ve got to resolve. There cannot be conflict between geological truth and artifact truth, and consequently we’ve got to find how to accommodate the two.

We are just at the beginning of archaeological investigation, not the end. And all I ask of you, my colleagues, is to consider the evidence with an open mind, and then, form your own judgements. But please, don’t be influenced by anything but the truth!

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