ioWA 405 



532. View in Cedar Valley quarry. Anamosa stage of Niagara limestone, Cedar 



Valley, Iowa (No. 147). 



533. The Buchanan gravels, an interglacial, probably Aftonian deposit of water- 



laid, cross-bedded sands and gravels. The boulders in foreground have 

 been thrown out of the gravel, and are of the Kansan drift type. The 

 gravels are overlain by a thin layer of Iowan drift with numerous large 

 granite boulders (see number 151) (No. 149). 



534. Granitic boulders of Iowan drift near Winthrop, Iowa (No. 150). 



535. View in Champion quarry, Stone City, Iowa; Anamosa stage of Niagara 



(No. 144). 



536. Mount Hope ; a hill of circumdenudation standing on a baseleveled plain ; 



composed of Saint Croix overlain by Oneota; from south side of Oneota 

 river; T. 100, R. 5, Sec. 34 (No. 14). 



537. Saint Peter sandstone, showing weathering effects ; T. 96, R. 5, Sec. 14, 



S. W. \ N. W. I- (No. 31). 



538. Beds of passage between Niagara limestone and Maquoketa shale ; T. 90, 



R. 4, Sec. 10; Delaware county, Iowa. Photographed by Calvin (No. 56). 



539. Niagara overlying Maquoketa, illustrating the effects of geologic structure 



on topographic form within the driftless area; the gently undulating 

 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 (No. 58). 



540. Stairway at " Devils Backbone," illustrating effects of weathering on Niagara 



limestone; northwestern part of Delaware county, Iowa (No. 64). 



541. Cross-bedding in sandstone; Saint Louis; Bellefontaine, Makaska county, 



Iowa (No. 75). 



542. Steffen's quarry, Cleona township, Scott county, Iowa. Pitted rock surface 



beneath Kansan drift. False bedding of Leclaire limestone. Iowa Geo- 

 logical Survey, volume ix (No. 6). 



543. Mount Vernon paha from south. Iowa Geological Survey, volume iv, pages 



181-184 (No. 12). 



544. Paha between Mount Vernon and Lisbon, Iowa (No. 13). 



545. South of Cedar river, Linn county, Iowa. Ultimate ramification of den- 



dritic drainage on loess mantle of Kansan drift sheet. Cedar Rapids sheet, 

 TJ. S. Geological Survey (No. 1). 



546. Erosion gullies in loess mantle on Illinoian drift sheet, Princeton township, 



Scott county. Iowa Geological Survey, volume ix (No. 17). 



547. Swallows' nests in loess, Clinton, Iowa (No. 19). 



548. Lingulate lobes of heavy loess near Iowan frontier, northwest of Princeton, 



Scott county, Iowa. Iowa Geological Survey, volume ix (No. 20). 

 519. Topography of Kansan drift sheet, showing slopes of larger ravines. South 

 of Cedar river,. Linn county, Iowa. Cedar Rapids sheet, U. S. Geological 

 Survey (No. 2). 



550. Wide floodplain of Wapsipinicon river, Scott county, Iowa; seen from road- 



way cut in loess-mantled hills of Iowan frontier. Leclaire sheet, U. S. 

 Geological Survey; Iowa Geological Survey, volume ix (No. 24). 



551. Broad valley of Cedar river below gorge south of Mount Vernon, Iowa. 



Mechanicsville sheet, U. S. Geological Survey (No. 26). 



552. Contact of Niagara limestone (Silurian) and Hudson River shales (Ordovi- 



cian). Above Lyons, Iowa (No. 30). 



LIX— Hum,. Geoi,. Soc. Am., Vot,. V.i, 1901 



