. The age of mammals in Europe, Asia and North America. Mammals, Fossil; Paleontology. ?1% ?;^' PLEISTOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 459 sively explored by Condon, Cope, Sternberg (who made the chief collect tions), and Russel (1882). It now presents a perfectly dry surface con- sisting of a light-colored mixture of sand and clay or dried mud of volcanic origin; all the fossils lie in this last friable deposit of volcanic dust. Though actually twenty miles distant from Silver Lake, the rich fauna of mammals and birds found has been described by Cope^ and Shufeldt, and referre
. The age of mammals in Europe, Asia and North America. Mammals, Fossil; Paleontology. ?1% ?;^' PLEISTOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 459 sively explored by Condon, Cope, Sternberg (who made the chief collect tions), and Russel (1882). It now presents a perfectly dry surface con- sisting of a light-colored mixture of sand and clay or dried mud of volcanic origin; all the fossils lie in this last friable deposit of volcanic dust. Though actually twenty miles distant from Silver Lake, the rich fauna of mammals and birds found has been described by Cope^ and Shufeldt, and referred to by Gilbert, as the fauna of the Silver Lake Equus beds. It is obvious that we have no means of correlating it in time with the lacustral move- ments either of Lake Bonneville or of Lake Lahontan, and that at present the correla- tion of this fauna with either of the phases of the Cdacial Epoch will be impossible un- less shore lines of the Silver or Christmas Lake region admit of investigation similar to that which has been so successful in the great ancient lakes to the south. The Silver Lake mammal fauna appears to be slightly younger or more recent than that of the Hay Springs Equus beds above described; both the camels and horses are somewhat more progressive in type. It is note- worthy that the bison does not occur in this rich fauna. We owe to Cope ^ (1889) and Shufeldt ^ (1892) peculiarly pictur- esque descriptions of this region as it may have been in Pleistocene times. Proof that the country was partly fluviatile and partly wooded is afforded by the presence of the muskrat (Fiber), the otter (Lutra), the beaver (Castor fiber), and the giant beaver (Castoro'ides). The supposed great mylodont sloth (Mylodon sodalis), an animal as large as the existing grizzly bear, also affords evidence of forested conditions and probably of abundant moisture; it is possible that this animal may prove to be a Mega- lonyx. The mammoth (f E. columbi) frequented the forests of the rive
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectpaleontology, bookyea
