496 PROCEEDINGS OF PHILADELPHIA MEETING. 



1 129 (18) . Bluffs on the upper Iowa or Oneota river, Saint Croi x capped hy Oneota ; 



lieight oOO feet plus ; near the mouth of Bear creek, Allamakee 

 county, Iowa, Photographed by Calvin. 



1130 (21). Oneota limestone; evenly bedded, fine quality stone; about 40 feet 



above Saint Croix ; Tp^ 100, R 5, Sec. 18, n!w. \ S. W. ], N. E. cor. 

 Photographed by Calvin, 

 1 Vol ( B22). Part of the " Oyster shell rim " east of Fall river, showing peculiar con- 

 cave topograiihic forms due to a bed of hard limestone charged with 

 the shells of IiiocmDntis overlying softer beds ; Benton grou]) ; north- 

 east of Hot Springs, South Dakota. 



1132 (25). Bluffs of Oneota limestone; on Yellow river below Ion; Tp. 96, R. 4, 



Sec. 24, N. E. ] S. E. }. Photographed by Calvin. 



1133 (29). Bluff of Oneota limestone; massive above, cherty partings at base; 



height 60 feet ; Tp. 96, R. 4, Sec. 16, S. W. 1 N. E. \. Photographed 

 by Calvin. 



1134 (33). Cascade at Pinneys spring; in Trenton limestone, Allamakee county, 



Iowa. Photographed by Calvin. 



1135 (31). Saint Peter sandstone, showing weathering effects ; Tp. 96, R. 5, Sec. 14, 



S. W. 1 N. W. ]. Photographed by Calvin. 



1136 (35). Upper Iowa or Oneota river, showing bluffs of Trenton limestone ; De- 



corah, Iowa. Photograi)he(l by Calvin. 



1137 (36). Effects of weathering on a blufi"of Trenton limestone, illustrating thin 



bedding, etcetera; Tp. 96, R. 6^ Sec. 17, S. E. ] S. E. ]. 



1138 (46). " Devils Den;" spring issuing from face of bluff of Trenton limestone; 



Tp. 99, R. 5, Sec. 19, N. W. 1 N. E. ] N. E. cor. Photographed by 

 Calvin. 



1139 (55). Natural fall; Niagara limestone; Cascade, Dubuque county, Iowa. 



Photographed by Calvin. 



1140 (56). Beds of passage between Niagara limestone and Maquoketa shale ; Tp. 



90, R. 4, Sec. 10; Delaware county, Iowa. Photographed by Calvin. 



1141 (58). Niagara overlying Maquoketa, illustratimr the effects of geologic struct- 



ure on topographic form within the driftless area; the gently undu- 

 lating lower slopes are underlain by the Maquoketa shale ; the steep 

 hills in the background are constructed of the overlying Niagara 

 limestone; view looking south from Lattners, near Graf, Dubuque 

 county, Iowa. Photographed by Calvin. 



1142 (63). Steamboat rock ; " Devils Backl)one," toi)ography of region similar to 



that of driftless area; northwestern i)art of Delaware county, Iowa. 

 Photographed by Calvin. 



1143 (64). Stairway at "Devils Backbone," illustrating effects of weathering on 



Niagara limestone; northwestern part of Delaware county, Iowa. 

 Photographed by Calvin. 



1144 (75). Cross-bedding in sandstone; Saint Louis; Bellefontaine, Makaska 



county, Iowa. Photographed by Bain. 



1145 (79) Cross-bedding in Coal iMeasures sandstone; Redrock, Marion county. 



Photographed by Keyes. 



1146 (80). Coal Measures sandstone and shale ; foot of Capitol hill, Des Moines, 



Polk count}', Iowa. Photograi)hed by Bain. 



1147 (83). Gypsum quarry face ; Cretaceous; Iowa Plaster Comjiany, Fort Dodge, 



Webster county. JPhotographed by Keyes. 



