FEATURES IN HISTORY OF LIFE ON PACIFIC COAST 



Slants belong to species not known in the Jurassic 

 ora of this region. In a few areas of the West 

 Coast, as at Vancouver Island, remains of Cretaceous 

 plants accumulated in sufficient quantity to form 

 coal beds. 



In the Eocene period, following the Cretaceous, 

 plant life was more abundantly preserved than at 

 any other time in the history of the Pacific Coast 

 region. It was during this time that the greater part 

 of the West Coast coal was deposited, largely 

 through accumulation of remains of coniferous 

 plants. There is good reason to believe that condi- 

 tions were unusually favorable during this time 

 both for accumulation of coal and for abundant 

 growth of plants over wide areas of low-lying land. 

 The Eocene flora is especially well known from the 

 coal mines of the Puget Group in western Washing- 

 ton, from the Swauk and Roslyn beds of eastern 

 Washington, from the Upper and Lower Clarno 

 beds of eastern Oregon, and from the lone forma- 

 tion of the eastern border of the Sacramento Valley 

 in California. At least two phases of this flora are 

 known. The earlier or Cherry Creek phase of the 

 eastern Oregon flora contains a considerable per- 

 centage of ferns and is more closely related to the 

 Cretaceous flora than is the Upper Clarno of Bridge 

 Creek, Oregon. In the upper flora walnut, birch, 

 alder, oak, maple and sycamore make up a large 

 percentage of the plants, and ferns are not known. 



From strata of the Oligocene period a very few 

 plants are known in the uppermost John Day beds 

 of eastern Oregon. 



The flora of the West Coast in Miocene time is 

 well shown at a number of localities. In the Mascall 

 Middle Miocene of the John Day region very abun- 

 dant remains represent about eighty species. In- 

 cluded among these plants are the following types: 

 willow 9 species, oak 7 species, elm, magnolia, tulip 

 tree, sycamore, acacia, maple 8 species, sequoia 3 

 species, yew, scouring rushes, and a ginkgo. A 

 flora resembling that of the Mascall beds is found 

 in eastern Washington and in several other regions 

 of the West. The flora of Corral Hollow in middle 

 California is referred to the Upper Miocene. The 

 splendid flora of the Auriferous Gravels from the 

 Sierra foothills of middle California has been gen- 

 erally recognized as Miocene, though Knowlton who 

 has most carefully studied it notes also a relation- 

 ship to the Eocene. Recent work has shown the 

 presence of an Eocene marine fauna in beds thought 

 by many to represent the same period as forma- 

 tions containing the Auriferous Gravel plants. 



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