PALEOZOIC STRATIGRAPHY OF ROCKY MOUNTAINS 127 



8. Cliff-making, massive dolomite, locally with algal structure. Light-buff 

 to brownish (dark-brown at Blacksmith Fork). In the Absaroka Range, 

 partly brecciated, mottled, brownish fragments in buff matrix. Sparingly 

 fossiliferous at Goose Creek Ridge. M.T., 270 feet, Blacksmith Fork. 



7. White to dark-drab or brown-gray, dense dolomite. Weak, breaking to 

 small angular fragments. Locally carries ostracods. M.T., 17 feet, Goose 

 Creek Ridge. 



6. Basal dolomitic breccia or conglomerate (not seen in Goose Creek Ridge 

 section), interleaving with, and giving place upward to, a massive, brown- 

 gray dolomite containing much calcite in seams and geodes, or to white or 

 drab, finely crystalline dolomite somewhat similar to Member 5. The 

 white dolomite carries corals at Goose Creek Ridge. M.T., 181 feet, Black- 

 smith Fork, where the two types of dolomite above described occur inter- 

 bedded. 



Trenton (Lower Bighorn) 



5. Typically white, almost chalky, fine-grained dolomite, breaking into small 

 angular fragments with relatively smooth weathered surfaces. At Living- 

 ston Peak interbedded with more coarsely crystalline, brownish dolomite. 

 Locally carries ostracods. 56 feet, Dead Indian Creek (typical throughout) . 

 M.T., 89 feet, Livingston Peak. 



4. Cliff-making, massive (rarely slabby), white to light-gray or light-buff dolo- 

 mite, medium to very coarsely crystalline, in many places in part with 

 brecciated structure. Sparingly fossiliferous in many localities. 147 feet, 

 Labarge Mountain. M.T., 153 feet, Blacksmith Fork, where it is underlain 

 by 149 feet of massive, dark-brown dolomite, medium finely crystalline, 

 with many seams of calcite (both members included under Member 4 in the 

 diagrams) . 



3. Like Member 4, but thin-bedded or closely jointed, weak. M.T., 60 feet, 

 Labarge Mountain. 



2. (Recognized in the Crandall Creek and Dead Indian Creek sections only.) 

 Cream to buff, finely crystalline dolomite in 2-foot beds. Fossiliferous. 

 M.T., 10 feet, Dead Indian Creek. 



1. In Wyoming, developed as a white to buff or rose sandstone, mostly soft 

 and friable; fossiliferous, locally with fish remains. 29 feet (plus?), Goose 

 Creek Ridge. Correlated with the Harding sandstone of Colorado. At 

 Manitou, very arkosic, and in part deeply stained (red and green) ; 47 feet 

 thick. Possibly contemporaneous with part of the Swan Peak quartzite. 

 Possibly of Black River rather than Trenton age. 

 Marked Disconformity 



Swan Peak Quartzite 

 Five hundred feet thick, in the Randolph quadrangle, northern Utah. 

 Geneva sandstone or quartzite, north end of the Wasatch Mountains, Utah. 

 Eureka quartzite, 200 to 500 feet thick, east-central Nevada. 



