Deep-Well Record of Fossil Mammal Remains in California

The writer not only aims to discuss the subject matter indicated by the title, but takes the occasion also to direct attention to a type of material met with in geological explorations for petroleum and important to the vertebrate paleontologist as well as to the practical field geologist. Remains of fossil mammals are commonly encountered in land-laid deposits of Tertiary or Pleistocene age where their presence may be looked upon as a source of some information concerning the conditions under which the sediments have accumulated. The mammals themselves, because of their complex structural characters and relatively restricted vertical range in geologic time, become excellent markers and age determinators. Moreover, a surprising amount of information concerning these forms may be drawn on occasion from scattered or fragmentary remains.