EVIDENCE THAT BEDS ARE AFTONIAN 129 



5. Weniger pit. — This is a sand pit located in the east half of section 

 18, township 84 north, range xliv west, in Monona County, Iowa, in the 

 bluffs facing the Missouri Valley. It shows 8 feet of sand and gravel on 

 which typical Kansan drift, 2 to 4 feet thick, rests unconformably. The 

 two deposits are separated by a distinct oxidized band and by a layer of 

 calcareous nodular plates (see plate 2, figure 1). 



The Aftonian here rises to about 40 feet above the Missouri bottoms, 

 the average altitude of these beds in this territory. 



Fragments of shells, probably SpJicerium, were found in the upper, 

 finer sand. 



6. Elliott pit. — This is a sand pit located in the northeastern part of 

 Turin, Iowa. The sand and gravel in this pit are typically Aftonian in 

 the cross-bedding, streaking with iron and MnOg, the presence of silt and 

 drift nodules or pellets and white, soft, calcareous nodules, the occurrence 

 of mollusks in the sand and mammalian remains in the gravel. 



Moreover, the position of these beds removes all doubt as to their iden- 

 tity. Superintendent W. E. Babcock, of the cement tile factory operating 

 this pit, reports that in boring in the pit they encountered, below the sand 

 and gravel, a layer of "dark clay which was like rubber," into which they 

 penetrated about 4 feet. They found it putty-like, tough, very hard to 

 work, and containing occasional boulders. This is evidently Xebraskan 

 drift, which is also well exposed in the same valley at Castana. 



The Aftonian was exposed to a depth of about 12 feet. In the greater 

 part of the exposure the fine sand lies above the gravel, though there is 

 some interbedding, but near the south end a layer of coarse, ferruginous 

 gravel rests on the sand. 



The bones and teeth were found in gravel at a depth of 10 to 12 feet 

 below the top of the Aftonian. 



A distinct band of bluish or reddish laminated silt was found above the 

 sand and gravel. It is about 2 feet thick, and evidently represents a slack- 

 water deposit of the Aftonian. It grades downward into fine sand. 



The superimposed formations, the Kansan drift, the Loveland, and the 

 loess, are well developed, and the entire section is typical. The sharp 

 contact line between the Kansan and Aftonian is shown in plate 2, 

 figure 2. 



The following vertebrate fossils were collected: 



8. Elephas or Mammut, a cervical vertebra (see ibid., plate 25, fig- 

 ures). 

 161. Part of rib of proboscidian. 

 166. Mammut americanum, sixth molar. 

 187. Camelus , first phalanx. 



IX — Bull. <5eol. Soc. Am.. Vol. 21. 1909 



