208 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



BOSWORTH FORMATION (continued): 



I (continued) : Feet 



This formation forms tlie base of the high cHffs on the south- 

 east face of Mount Daly and Paget Peak. 

 The lower portion of i was measured and the upper parts esti- 

 mated. The thickness given is probabh- loo feet oi more 

 less than the actual thickness. 



2a. Shaly and thin-bedded, gray and dove-colored, compact fine- 

 grained dolomitic limestone weathering buff and light gray. 

 Thicker layers occur in bands from i to 6 feet thick 422 



2b. Greenish siliceous shale with thin interbedded layers of sili- 

 ceous, compact, gray limestone 48 



Fauna: 



At about this horizon in the Castle Mountain section 20 

 miles southeast of Mount Bosworth small trilobite 

 heads of the genera Ptychoparia and Solcnophura 

 occur in a band of gray and bluish black limestone, and 

 just below fragments of a species of Obolus. 

 2c. Limestones similar to 2a 5x7 



Total of 2 987 



3. Variable arenaceous shales with alternating bands of color — 

 greenish, deep red, buff, yellow, and gray. 

 Numerous mud cracks and ripple-marks occur on many of 

 the layers 268 



Total of Bosworth formation 1,855 



Total Upper Cambrian 3,590 



Note.— The 1,855 feet of strata included in i, 2, and 3 

 remind me, in lithologic character and appearance, of strata 

 of the upper portions of the Cambrian Belt Terrane of 

 Montana. No traces of life were observed and the shaly, 

 banded character of the beds is very striking. 



MIDDLE CAMBRIAN 



ELDON FORMATION [Walcott, 19080, p.3] : 



10. Irregularly bedded, gray, siliceous and arenaceous limestone in 

 thick layers above and thin layers below; at 192 feet from 

 the base a bed of bluish black limestone is fossiliferous. 

 Above the fossiliferous bed the strata become more massive, 

 arenaceous, steel gray in color, weathering to a light gray. . . 410 



Fauna (192 feet above the base) : 

 Agnostus, sp. 

 Ptychoparia, 2 species. 

 Bathyuriscus-like pygidium. 



lb. Light and dark gray, thin-bedded, arenaceous limestone, weath- 

 ering to a light-gray color no 



ic. Massive bedded, siliceous, fine-grained, compact, dark bluish 



gray limestone 197 



