TRIASSIC. 

 FormMions in the Richmond area. 



519 



The divisions are described in much detail and with reference to exact local- 

 ities in the pages following this tabulation in the report cited. 



J-K 10. NORTHERN CALIFORNIA. 



The Triassic of Shasta County, Cal., from which fossils were first described 

 by Gabb,''" has been studied by Smith, who distinguished the Pitt shale (now 

 spelled Pit), Swearinger slate, and Hosselkus limestone. (See table, p. 374, Chap- 

 ter VIII.) The Pit shale is the upper part of the so-called "Pitt formation," 

 concerning which Smith ^^^* writes : 



The Pitt formation overlies conformably the McCloud limestone and consists, roughly 

 estimated, of about 3,000 feet of siliceous and calcareous shales, conglomerates, and tuffs. 

 The rocks in most places are highly metamorphosed, very poor in fossils, and folded to such 

 a degree that the stratigraphy is obscure. The general strike is north and south and the dip 

 generally toward the east, since most of the folds are overthrown. 



The formation is largely developed in the region near the junction of the Pitt and the 

 McCloud rivers. It contains both Carboniferous and Triassic rocks, in an apparently con- 

 formable series, both with a decisive fauna, the presence of Upper Carboniferous and Middle 

 Trias being proved by fossils. 



The lower part of the "Pitt formation" consisted of the "McCloud shales" 

 (Carboniferous). This name has now been abandoned by the Survey, the shales 

 being included in the Nosoni formation of Diller"® (Pennsylvanian) . The name 

 McCloud is, however, retained for the underlying limestone (also of Pennsylvanian 

 age). 



Details of faunas and local occurrences of the two divisions of the " Pitt forma- 

 tion" are given by Smith in the paper cited above, followed by an account of the 



