53() EEPORT UNITED STATES GEOLOGICAL SURVEY. 



ABSAROKA RIDGES. 



West of tlie Fontenelle Hogbacks and east of Ham's Fork Basin is a 

 plateau-like ridge of Carboniferous beds, wliicli, when followed to tke 

 northward, develops into several parallel ridges, and finally culminates 

 in the Wyoming Eange. Only that portion lying between Ham's Fork 

 Basin and the Hogbacks was visited. Two stations, Nos. 25 and 26, 

 were made on this plateau-topped ridge. Quartzites form the summit 

 dipping to the westward, and below the summit limestones outcrop with 

 fragments of Zaphrentis. The summit is well timbered. Looking north 

 all the dips appear to be toward the west. What the rocks are, how- 

 ever, it is impossible to say definitely, but the strikes of Station 25, car- 

 ried north, would seem to indicate them to be of Carboniferous age, with 

 perhaps later beds northwest. I am equally uncertain about the south 

 end of the ridge, and the relations of the overlying Wahsatchbeds on the 

 west on Ham's Fork. On the east there is a rather abrupt bluft' face, 

 and a short distance east in the valley beds of sandstone and limestone 

 with Ostrea soleniscua are found, also dipi^ing westward, seeming to abut 

 against the westward-dipping Carboniferous limestones. There is prob- 

 ably a fault extending along the eastern side of the range, but the junc- 

 tion is so covered by debris that it can only be assumed. 



MERIDIAN RIDGE. 



Extending southward from Thompson's Plateau to Slate Creek is an 

 antichnal ui)hft, meridian fold, that forms the western rim of the Green 

 Eiver Basin at this part of its extent. This ridge was crossed by us at 

 two points only, viz, south of Fontenelle Creek and near Slate Creek. 

 The highest portion of the ridge is north of Fontenelle Creek, where an 

 elevation of about 8,000 feet is reached. Labarge Creek cuts a canon 

 through the north end of the ridge. The upper portion of the ridge not 

 being visited, of course its description is not attempted. It is probable 

 that Carboniferous and Jurassic rocks form the main part of it, and it 

 has been so colored. Approaching the ridge via Fontenelle Creek the 

 Green Eiver Group is seen to terminate in a bluff' facing the ridge, with 

 its strata inclining gently towards the eastward. From beneath these 

 strata the Wahsatch beds appear abutting against the more steeply in- 

 clined older beds that form the fold which makes the ridge. At the Fon- 

 tenelle the trend of the ridge is about due north and south. Towards 

 Labarge Creek it is little west of north. The following section was 

 made on the western slope of the ridge south of Fontenelle Creek. The 

 edges of the strata face the west, the strata being almost horizontal on 

 the summit, but dipping steeply to the eastward on the east side of the 

 ridge. 



Section Ko. 7. 

 Top. 



6. A redcTisli qiiartzite, thin and without fossils. It forms the summit in"| 



some places and is entirely eroded away in others 



5. Bluish limestone containing Pentacrinus asierisciis, Ostrea strigulecula, I inofpf^f 



Camplonectes bellistriatus, Mytilus ? Myalina ? Modiola ? j 



Trigonia ? Ostrea ? 



4. Reddish sandstone J 



3. Bluish limestones, laminated and blue argillaceous shales and slates ? 150 feet 



2. Bluish and gray limestones 5 



1. Reddish quartzites which appear to reach to the valley of the creek to 

 west of ridge. They are much brohen and appear to have been ab- 

 ruptly folded. The distance to the creek level is about COO feet. 



Total , 850 feet. 



