20G C. D. WALCOTT — PRE-CAMBRIAN POSSILIPEKOUS FORMATIONS 



Chamberlain shales. — This formation is composed of a series of dark 

 silicious and in places arenaceous shales. Ripple-marks, mud-flows, and 

 sun-cracks were occasionally seen, but no traces of life were observed. 

 The dark shales frequently form low cliffs along the canj'on side, near 

 the beds of the streams. 



The typical localities are on the ridges between Chamberlain and Saw- 

 mill creeks, southeast of Neihart. Estimated thickness, 1,500 feet. 



Neivland limestone. — At the typical locality on Newland creek the lime- 

 stones are thin bedded, the layers averaging from 2 to 6 inches, with shaly 

 partings of variable thickness between them. In the section in Sawmill 

 canyon, near Neihart, the layers are somewhat thicker, more impure, and 

 with a greater number of beds of interbedded shale. The prevailing color 

 of the limestone is dark bluish-gray on fresh fracture, and buff to straw 

 color on the weathered surface. The limestones are hard, man}' of the 

 layers breaking with a conchoidal fracture, and some of the purer por- 

 tions give off a bituminous odor when crushed with the hammer. The 

 thickness of the formation is estimated at 2,000 feet. A careful search 

 at several localities failed to bring to light any traces of fossils. 



The typical localities of the Newland limestone are on Newland creek 

 10 miles north of White Sulphur springs, and on Sawmill creek, 4 miles 

 south of Neihart. 



Greyson shales. — Dark colored, coarse, silicious and arenaceous shales, 

 passing above into bluish-gray, almost fissile shales, which Avhen broken 

 up weather to a light graj^ fissile shale, resembling a poor quality of 

 porcelain. These in turn are succeeded by dark gray silicious and are- 

 naceous shales, with interbedded bands of buff-colored sandy shales and 

 occasional laj^ers of hard, compact, greenish gray and drab silicious rock. 

 At the base of this series, in Deep Creek canyon, a belt of quartzites oc- 

 curs, interbedded with shales, the base of the quartzites showing 10 feet 

 of interformational conglomerates, composed of sand and jDcbbles up to 

 8 inches in diameter, and derived from the subjacent Belt rocks. 



The conglomerates and the quartzites are about 100 feet in thickness. 

 This local deposit does not occur at the same relative horizon in the Saw- 

 mill Creek section, near Neihart. 



Fossils were found in the lower part of this series in Sawmill canyon 

 and near the mouth of Deep Creek canyon, just above Glenwood post- 

 office. They include numerous trails, Hehmnthoidlchnites ? neihartensis, 

 H. ? spiralis, H. meeki. Planalites corrugates, P. superhus, and many frag- 

 ments of crustaceans referred to the Merostoma. Onl}^ one form, Beltina 

 danai, is named. 



The typical section is on the side of the ridge between GrcA'son and 

 Deep creeks, where the estimated thickness is 3,000 feet. 



