128 B. SHIMEK PLEISTOCENE OF SIOUX FALLS AND VICINITY 



his work with that of Todd. He considered the flat plain on the west side 

 of the Big Sioux a Wisconsin drift-plain and contrasted it with the Lyon 

 Connt}^ surface, which is higher and "older and its drainage more per- 

 fectly developed" (page 94). He also recognized "a finely developed 

 Wisconsin gravel train" following the Big Sioux (pages 130, 138), and 

 Wisconsin gravel terraces along other streams (pages 141-143). Xot 

 only did he recognize the Altamont moraine suhstantially as traced by 

 Todd on the South Dakota side, but he extended it into the western part 

 of Lyon County, Iowa, and represented it definitely on the map of that 

 county (pages 137-143). He states that "from the point where the mo- 

 raine crosses the river west of Granite to Sioux Falls it is easily traced as 

 a well defined boulder-strewn ridge. It passes east of Sioux Falls and 

 crosses the river 2 miles northeast of the town." In the last particular 

 he disagrees with Todd, who located the moraine south of Sioux Falls. 



Wilder considered the drift of Lyon and Sioux counties Kansan, but 

 concluded with Salisbur}^, Bain, Leverett, and Todd (page 128) that the 

 lower drift in the Illinois Central Bailway cut east of Sioux Falls, and 

 in similar cuts in Sioux Falls, is Kansan, the upper drift in his opinion 

 being Wisconsin. 



He also observed sand, gravel, and clay beneath the drift, of which he 

 says (page 97) that they are not readily classified, but probably should be 

 referred to the Pliocene. He found that these sands are not local ; that 

 at Akron^ and Sioux City they contain mammalian fossils, and that they 

 are younger than the Cretaceous and older than the drift. On the basis 

 of the decision that the lower drift at Sioux Falls is Kansan, he refers 

 these sands and gravels to the Buchanan. 



The next extended contribution was that of T. S. Bendrat,^ who agreed 

 on the whole with Todd. In plate II he figures the Altamont moraine 

 south of Canton and again south of Sioux Falls, and connects these eleva- 

 tions by the chain of knobs already mentioned (page 85). He represents 

 the moraine as loess-covered. He states that sometimes sand and gravel 

 separate two blue tills, and sometimes a blue and a yellow till, and evi- 

 dently considered them a part of the drift. 



In 1908 Todd again discussed a portion of our territory in the Elk- 

 point folio,^^ and expressed doubt that the prevailing drift is Kansan, but 

 suggested that it may be lowan (page 3). The sketch-ma]i, figure 3, 



8 The elephant bones reported from Akron are probably those which the writer recently 

 secured for the Iowa Geological Survey. They are bones and teeth of Mammut mcrifi- 

 cum and are Aftonian. 



'The geology of Lincoln County. South Dakota, and adjacent portions. American 

 Geologist, vol. xxxiii. 1004. 



" Geological Atlas of the United States, Elkpoint folio. U. S. Geological Survey, 



