How long does it take for the mineral matter to replace entirely the original bones? Ages upon ages. I found on the plains of Kansas a quarry of elephant bones, from which I took over two hundred teeth of the Columbian mammoth, some of the larger ones weighing fourteen pounds each. The broken bones were scattered by the ton through the matrix. I had them analyzed by Dr. Bailey, the head of the chemical department of Kansas State University, and he found only ten per cent. of silicified matter in them; that is, they were only ten per cent. less rich in phosphate of lime than Armour’s ground bone meal. This great elephant lived about the time of the Ohio mastodon, whose bones have been found in such a position as to indicate that they were buried when Niagara Falls were six miles below their present site. So if we knew how long it has taken the river to dig six miles of its big ditch, we could tell how long it has taken to impregnate the bones of the mammoths in central Kansas with ten per cent. of silica. How foolish, then, to speak of completely petrified men, when man had probably not made his appearance in America at the time of the mammoths.
The rocks of the Texas Permian, as I have already mentioned, are of red clay filled with concretions of every conceivable form. I remember once rounding a butte and seeing before me hundreds of cocoanuts, some whole and others with the brownish shells broken, showing the white meat within. Absent-mindedly, I sprang from my horse to feast upon them, to find that they were concretions which had so closely imitated cocoanuts in shape and color that even I, an experienced collector, had been momentarily deceived. I knew, too, of a man who exhibited a collection of large concretions as fossil Hubbard squashes, and I heard no one doubting that they were all that their labels claimed.
There are two distinct formations in the Permian of this part of Texas which give character to the surface of the country. They are as different as if separated by hundreds of miles. I visited one locality on Pony Creek, where the red beds lay on top of the gray beds conformably. Looking to the west, a vast panorama, desolate and forlorn, of crumbling and denuded bluffs, narrow valleys, and beetling crags, spread out before me, with the usual red color dominant everywhere, its monotony relieved only here and there by the green of some stunted mesquite or patch of grass. To the east stretched the narrow valley of Pony Creek, whose topography is the same as that which is so familiar to the residents of eastern Kansas—a ledge of gray sandstone forming a narrow escarpment on either side and following the trend of the hills around the ravines, with grass coming down in gentle swells to meet it or rising to it from the bottom lands below. The greatest thickness of this sandstone, as I observed it, was at the head of a narrow gulch near my camp in the creek bottom, eight miles north of Seymour. I made a section there and sent samples of the rock to Munich.
I observed this rock under peculiar circumstances, and found that it solved an interesting problem—that of the water supply of the red beds. I discovered why the water that falls where these beds only are exposed runs off soon after a shower, except when caught in natural or artificial tanks, so that there are no wells or springs in the red beds, while in the gray beds there are always springs and streams of running water.
In the September of my 1901 expedition, the heaviest rain since May fell in torrents for an hour and a half; water lay everywhere on the surface of the ground. But soon after the rain stopped, it had all disappeared. My son had discovered across the creek a locality which was rich in fossil invertebrates, consisting chiefly of straight and coiled nautilus-like shells; and shortly after the downpour I went over to set to work collecting them, as Dr. Broili had told me that the Munich Museum was anxious to secure such a collection. I had not been long at work before George shouted to me that if I did not want to swim I would better cross the creek again at once. I followed his advice so hastily that I left my tools behind. Instantly, a raging, boiling flood of water covered the rocks in the bed of the creek, over which I had just crossed dry-shod, and rapidly rose to a height of eight feet, threatening to submerge my camp.
Looking for a good place to work on my side of the creek, the west, I found the gulch which I have referred to above. There was a level floor, formed by the first stratum of the gray beds, extending about five hundred yards to a ledge of red sandstone, eight feet thick. The floor was covered with debris washed from the red beds. To my astonishment, although the surface was dry, a flood of water was rushing out from under the upper deposits and tumbling in a miniature waterfall over the gray ledge, which was nearly five feet thick, into the ravine below.
The rock I found to be composed of four layers of sandstone. The upper layer, eight inches thick, is composed of fine-grained sand, which seems to have been ground to an impalpable powder by the beating of the waves. It is very compact and heavy, and upon exposure, breaks into rectangular blocks, so perfect in shape that they can be used for building purposes without being touched by hammer or chisel. The second layer breaks into large blocks of many tons’ weight. It is coarser grained than No. 1, and is about twenty inches thick. It contains a few casts of invertebrate fossils. No. 3 is twelve inches thick, and is of the same general character as the other layers. It is literally packed with casts of straight and coiled shells related to our living nautilus. They are mingled in great confusion. I believe some of the coiled shells are a foot in diameter. This stratum is not so compact as the others, and seems to contain more lime. No. 4 is a very solid gray sandstone, eight inches thick, its upper surface crossed at various angles by elevated ridges of harder material.
From these observations, I am led to the conclusion that the pervious nature of the red beds, which in the valley of the Wichita are about three hundred feet thick, allows the water to sink rapidly down through them until it reaches the impenetrable gray sandstone; from which it runs off at whatever angle the rocks may be tilted.
CHAPTER XI
CONCLUSION
