One of the most curious places we met in all our route, was a mountain ridge of fossil shells, from which a great number of the above-mentioned specimens were taken. During our second day’s march from the mouth of the False Washita, we were astonished to find ourselves travelling over a bed of clam and oyster shells, which were all in a complete state of petrifaction. This ridge, which seemed to run from N.E. to S.W. was several hundred feet high, and varying from a quarter to half a mile in breadth, seemed to be composed of nothing but a concretion of shells, which, on the surface, exposed to the weather for the depth of eight or ten inches, were entirely separated from the cementing material which had held them together, and were lying on the surface, sometimes for acres together, without a particle of soil or grass upon them; with the colour, shapes and appearance exactly, of the natural shells, lying loosely together, into which our horses’ feet were sinking at every step, above their fetterlocks. These I consider the most extraordinary petrifactions I ever beheld. In any way they could be seen, individually or in the mass together, they seemed to be nothing but the _pure shells themselves_, both in colour and in shape. In many instances we picked them up entire, never having been opened; and taking our knives out, and splitting them open as we would an oyster, the fish was seen petrified in perfect form, and by dipping it into water, it shewed all the colours and freshness of an oyster just opened and laid on a plate to be eaten. Joe and I had carefully tied up many of these, with which we felt quite sure we could deceive our oyster-eating friends when we got back to the East; yet, like many other things we collected, they shared the fate that I have mentioned, without our bringing home one of them, though we brought many of them several hundreds of miles, and at last threw them away. This remarkable ridge is in some parts covered with grass, but generally with mere scattering bunches, for miles together, partially covering this compact mass of shells, forming (in my opinion) one of the greatest geological curiosities now to be seen in this country, as it lies evidently some thousands of feet above the level of the ocean, and seven or eight hundred miles from the nearest point on the sea-coast. In another section of the country, lying between Fort Gibson and the Washita, we passed over a ridge for several miles, running parallel to this, where much of the way there was no earth or grass under foot, but our horses were travelling on a solid rock, which had on its surface a reddish or oxidized appearance; and on getting from my horse and striking it with my hatchet, I found it to contain sixty or eighty per cent of solid iron, which produced a ringing noise, and a rebounding of the hatchet, as if it were struck upon an anvil.