140 ENVIRONMENT OF VERTEBRATE LIFE, ETC. - 



The inference drawn from this is that during a portion of Paleozoic time the 

 Pacific Coast region from British Columbia to California constituted a single 

 geological province. This became land in the Mesozoic and was already 

 uplifted and folded before the great intrusions which metamorphosed the 

 rocks. 



Farther north in Washington, in the Republic mining district. Paleozoic 

 rocks are again shown in a considerable exposure. Umpleby,^ discussing 

 this area, says: 



"The oldest rocks exposed in the district are the metamorphic equivalents 

 of a great series of shales, sandstones, limestones, and lava flows which are of 

 Paleozoic age, and are provisionally assigned to the Carboniferous. After the 

 deposition of this series, the area passed through a long period of crustal disturb- 

 ance which, although not developing sharp folds, metamorphosed the beds and 

 raised the area far above sea-level. Either during this period of crustal disturb- 

 ance or shortly thereafter great batholithic masses of grandiorite were intruded 

 into the Paleozoic series. * * * 



"The Paleozoic rocks are very uniformly but not intensely metamorphosed. 

 True schists are not common, and in many instances the limestone has not been 

 changed to marble. Nevertheless, the series has been so disturbed that a given 

 set of characteristics seldom persists for more than a short distance in any direc- 

 tion. Neither bottom nor top of the series was found. 



"Black carbonaceous argillite is the predominant rock type, although bluish- 

 gray nonfossiliferous limestones have a wide development. Massive gray quartz- 

 ites were noted in one exposure southwest of Republic. Porphyries of inter- 

 mediate and basic composition are found both as dikes and sills, apparently 

 intruded into the series before its metamorphism. The age relations of the 

 various phases of the series are not obvious from studies in the Republic area, but 

 to the north, at Phenix, British Columbia, LeRoy reports a section including all 

 the above types of rocks, which he divides into three parts with an unconformity 

 between the upper two. His section places the argillites in the upper part, 

 separated from the limestones and tuffs (no tuffs of this age were noted at 

 Republic) by a pronounced unconformity, while the lower member is quartzite 

 with intruded dikes and sills of basic porphyrites. The Paleozoic beds are 

 folded and metamorphosed, and are in marked contrast with the overlying 

 Tertiary series, in which folding is less marked and the beds are not metamor- 

 phosed. 



"It is not possible, on the strength of facts now known, to assign this forma- 

 tion to a definite place in the Paleozoic series. Near Republic the formation 

 carries certain fossils, not well preserved, but which seem to be crinoid stems. 

 In an exposure of limestone near the top of Buckhorn Mountain, in the northwest 

 part of Republic quadrangle, several fossil crinoid stems were found which are 

 not out of harmony with a provisional assignment to the Carboniferous. These 

 remains, together with the lithologic characteristics of the series, suggests a 

 correlation with the Cache Creek series of Dawson, which is of Carboniferous age. 



^ Umpleby, J. B., Geology and Ore Deposits of Republic Mining District, Washington 

 Geological Survey, Bull, i, p. 15, 1910. 



