STRATIFICATION OF THE LOESS 145 



suggested lamination iii the higher bluffs near the river indicated by the 

 little horizontal planes already mentioned. 



This horizontal lamination in the general loess mass at Saint Joseph 

 may also be seen in the higher bluffs, especially at points somewhat 

 retired from the exposed cliffs along the immediate valley. On Farrand 

 street between Fifth and Fourth is a butte-like small hill left by the 

 cutting away of the streets, opposite the county jail, showing conspicu- 

 ous horizontal stratification. This is about 150 feet above the river and 

 5 blocks from it. At Horns heights, half a mile from the river, are con- 

 spicuous and frequent exposures formed by cutting the street grades. 

 Here the loess is generally plainly stratified to near the top of the de- 

 posit, and in some cases is interlaminated with sand and gravel, evidently 

 of foreign origin, some pebbles being as coarse as duck's eggs. It also 

 contains pockets of sand so extensive that it is used for mortar, etcetera. 

 Miss Owen stated that some years ago two masses of red sandstone (red 

 Sioux quartzite) were found in the loess at Saint Joseph, a fact which 

 has been reported at various places in Iowa by Chamberlin and Salis- 

 bury and by McGee. 



In general, then, it appears that the undifferentiated affinities of the 

 loess are toward the north ; its extreme derivaties are toward the south. 

 The resultant direction of all ice movement and of all the great streams 

 along which the loess is found in greatest amount is from north toward 

 the south. This coincidence is significant of the relation of the loess to 

 the southward drainage of the country, and requires that the agency of 

 water shall take a paramount rank in any consideration of its origin. 



SIGNIFICANCE OF ITS FA UNA 



The general horizontal stratification of the loess, when considered in 

 connection with its preference for the valleys of the great streams and 

 for the higher lands where it grades into the drift, seems to set a quietus 

 on other interpretation of its fauna than can be made to harmonize with 

 an aquatic origin for its structure, origin, and distribution. The fact that 

 terrestrial forms are common in the laminated loess and that aquatic 

 ones are rare must be explained in consonance with a broader and con- 

 trolling general truth. 'J'errestrial fossils are not uncommon in marine 

 formations. He would be very bold who should assign the Dakota 

 sandstone formation to other than oceanic waters on the ground that it 

 contains many land plants. Many land forms may exist in an aquatic 

 formation, but the existence of a single aquatic fossil species in the loess re- 

 quires the presence ofivater. Many have been identified by good author- 

 ities. How, then, have the land snails been introduced so abundantly 

 into the loess ? 



