8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. SS 



Character. — Blue to bluish gray, thin-bedded, fine-grained lime- 

 stones and shales, with some oolitic, concretionary, and intraforma- 

 tional conglomerate layers. 



Thickness. — In Blacksmith Fork, 759 feet; in the section west of 

 Liberty, 731 feet. 



Organic Remains. — Abundant Middle Cambrian fossils. 



Spence Shale 



Type Locality. — Spence Gulch, a ravine running up into Danish 

 Flat from Mill Canyon, about 5 miles west-southwest of Liberty,. 

 Bear Lake County, Idaho. This shale occurs at the base of the Ute 

 formation. " 



Derivation. — From Spence Gulch, the type locality. 



Character. — Argillaceous shales. 



Thickness. — In the section west of Liberty, 30 feet; in Black- 

 smith Fork, 30 feet. 



Organic Remains. — An extremely abundant and varied lower 

 ]\Iiddle Cambrian fauna. 



Langston Formation 



Type Locality. — The most readily accessible locality for this 

 formation is in Blacksmith Fork, but the strike of the beds (as 

 shown on the eastern half of Map 3 of the Fortieth Parallel Survey) 

 carries the formation into the valley of Langston Creek, and the 

 formation is given that name. 



Derivation. — From Langston Creek. 



Character. — Massive bedded, bluish gray limestone with many 

 round concretions. 



Thickness. — In Blacksmith Fork, 107 feet; in the section west 

 of Liberty, 30 feet. 



Organic Remains. — Lower IMiddle Cambrian fauna. 



Brigham Formation 



Type Locality. — West front of the Wasatch Range, northeast of 

 Brigham, Box Elder County, Utah. 



Derivation. — From Brigham, near the type locality. 



Character. — Massive quartzitic sandstones. 



Thickness. — At Brigham, 2,000+ feet; in Blacksmith Fork,. 

 1,250 feet; and in the section west of Liberty, Idaho, i,ooo-|- feet. 



The Brigham formation is the overlapping shore deposit of Mid- 

 dle Cambrian time along what is now the Wasatch Range. To the 

 northwest, in the Belt Mountain region of Montana, the upper part 



