MONOCLINAL RIDGES 465 



Monoclinal Ridges 

 (Marked instances only) 



376. East of Twin Sisters peaks, Colorado. 



401. Dakota sandstone, Perry park, south of Denver, Colorado. 



402. Vertical Red beds, Perry park, Colorado. 

 403-406. Garden of the Gods, Colorado. 



410. Colorado City, Colorado ; Triassic and Jurassic. 



663, 664. Hogback of upturned Cambrian sandstone, Indian creek, west of Town- 

 send, Montana. 



672. Lower Paleozoic section, north fork of Dearborn river, Montana. 



673. Carboniferous limestone cliff of mount Dearborn. 

 712. North end of Clayton valley, capped by basalt. 



1099. Hogbacks of Dakota sandstone, Buffalo gap, Black hills, South Dakota. 

 1216. Silurian quartzite, Rathole mountain, valley of James river, Virginia. 

 1268. Paleozoic rocks southwest of Sheridan, Big Horn mountains, Wyoming. 

 1282. Jurassic rocks, Como (Aurora), Wyoming. 



Mud Cracks 



453. Triassic sandstone from Portland, Connecticut. 



1167. Recent mud cracks, Skin quarter, Virginia. 



Natural Bridges 



1109. Jurassic sandstone near Buffalo gap, Black hills, South Dakota. 

 1080. Protoceras sandstone, Big Bad lands, South Dakota. 

 1189-1191. Natural bridge, Virginia. 

 1314. Rhyolite, Bridge creek, Yellowstone park, Wyoming. 



Natural Coke 



1168. Fragment of prismatic coke at Gayton, Virginia, at contact with vertical 



trap dike. 



1169. An outcrop of columnar coke, north of Saunders slope, Gayton, Virginia. 



Potholes 

 281. Canyon of fork of Mokelumne river, California. 



Quarries 



508. Oolite quarry, Steinsville, Indiana. 



510. Hunter's quarry, Bloomington, Indiana. 



511. Johnson's quarry, Bloomington, Indiana. 

 521. Gypsum quarry, Fort Dodge, Iowa. 



532. Cedar Valley quarry, Iowa. 



535. Champion quarry, Stone City, Iowa. 



558. Bieler's quarry, Cedar valley, Iowa. 



590. Granite quarry, Hallo well, Maine. 



781. Quarry in Medina sandstone, Lockport, New York. 



