SIGNIFICANT FEATURES IN 



THE HISTORY OF LIFE ON 



THE PACIFIC COAST 



BY JOHN C. MERRIAM 



Professor of Palaeontology and 



Historical Geology, University of California 



INTRODUCTION. There are many significant feat- 

 ures in every phase of West Coast palaeontology, 

 but in certain aspects the history of life in this 

 region is as yet imperfectly known, and little of 

 world interest has been contributed. For a con- 

 siderable portion of the earlier history of the lower 

 animals we have here only a meagre record com- 

 pared with that of the Atlantic Coast. Our story of 

 the plants is largely that of the later periods. Of 

 the age of amphibians we have no amphibian 

 record. Of the wonderful world history of the 

 great reptile class we know but a limited portion of 

 the record of two groups. In the evolution of mam- 

 mals we lack entirely the long record of Eocene 

 time. After subtraction of the factors which are 

 poorly represented there is much remaining, and 

 it is to the features which are here unusually well 

 expressed that the visitor will naturally be at- 

 tracted. 



THE HISTORY OF PLANTS. Our knowledge of the 

 history of the plant kingdom in the Pacific Coast 

 region is much less advanced than that of many 

 groups of animals. Of the plant life from the older 

 or Palaeozoic formations very little is known on the 

 western border of the continent, and not until we 

 reach the next great division, the Mesozoic, do we 

 find material which has attracted especial interest. 

 The oldest well-known flora is that of the Jurassic 

 period of the Mesozoic described from Oroville in 

 California, Thompson Creek in Oregon, and other lo- 

 calities. In this group are many ferns, cvcads, and 

 the strange ginkgos now almost extinct. It includes 

 many types known also in Jurassic areas of the 

 Old World. 



The Cretaceous flora is especially well repre- 

 sented in the great thickness of deposits of this 

 period in the northern end of the Sacramento Val- 

 ley in California. It contains many ferns, cycads, 

 conifers, and a few of the higher flowering plants. 

 Ginkgos are not known, but are found in a later 

 flora. Almost without exception the Cretaceous 



88 



