A Pliocene fauna from Western Nebraska / by W.D. Matthew and Harold J. Cook.

  • Matthew, William Diller, 1871-1930.
Date:
1909
Catalogue details

Licence: In copyright

Credit: A Pliocene fauna from Western Nebraska / by W.D. Matthew and Harold J. Cook. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    1909.] of dark gray volcanic ash, two feet thick. Merychippua is the most abun- dant fossil, several incomplete skeletons were found by our party, besides numerous teeth and jaws. Two or more species of camels, one referable to Alticamelus, another to Protolabis, are represented by skulls, jaws and parts of skeletons. A large eervid, provisionally referred to Palceomcnjx, and frag- mentary remains of Blastomeryx, Merycodus, ‘iCynodcsmus and other car- nivora and rodentia, were found; large and small tortoises are common. Overlying the eroded surface of the Sheep Creek beds are the remains of a formation which we regard as an outlier of the Ogalalla, which covers the plains to the south of the Platte and extends southward and eastward into Kansas. The typical Ogalalla is composed of clean sand, with a con- siderable amount of gravel and pebbles of hard rock, scattered through its mass or collected in layers, and the whole mass cemented to a varying extent by lime. It is known to the Kansas geologists as the “mortar-beds.” The older Miocene formations in the central Plains (Arickaree) are composed of a comparatively muddy sand, and lack the hard pebbles and gravel derived from the mountains. Even the coarse channel deposits in these older formations are usually composed mostly of mud-pebble conglomerates, not of crystalline or metamorphic rock pebbles. The Snake Creek Beds, as we shall call this supposed local facies of the Ogalalla, lack this calcareous cement at the typical locality, but are other- wise very like the “mortar-beds” of the Republican River valley. They are composed of a clean sand, with gravel scattered through it, especially in certain layers, and mantling the eroded surface of the Sheep Creek beds. Locally the gravel is concentrated in what appear to have been heavy channel beds, and the sand has been in large part removed, probably by seolian erosion, leaving a residual mantle of some thickness wherever these channel deposits occurred. Scattered through the undisturbed sands of the formation are bones, jaws, etc., of a great variety of fossil mammals, and in the old channel beds are vast numbers of jaws, teeth, and water-worn frag- ments of bone, forming in places a bone-bed several feet thick. Complete skulls and associated skeletons appear to be very rare. The bones are hard and uncrushed, but for the most part more or less waterworn. Their state of preservation is very much as in the sands of the Niobrara River further to the eastward, and in the fossiliferous sand formations of the Pleistocene.