ON THE MINNESOTA RIVER. 



489 



At some points the drift deposits were in stratified beds, and there two layers 

 could be detected containing fresh-water and land shells, separated from each other by 

 about six feet of sand and gravel ; but more frequently the different members were 

 blended together, and then no shells could be discovered. 



We were never able to discover any fossils in the ash-coloured clay, No. 1, of the 

 following section of the drift formation, as it presented itself high up on the Blue 

 Earth River. 



1. Ash-coloured clay, ...... 8 



2. Coarse sand with some pebbles, . . . .2 



3. Ash-coloured clay marl,* . . . . .7 



4. Sand and pebbles, with small boulders at base, . . 8 



5. Sand, with fresh-water shells, ..... G 



6. Sand and gravel, ...... 6 



7. Sand, with fresh-water shells, ..... 8 



8. Soil and subsoil, ...... 6 



The lithological characters of both beds of clay, Nos. 1 and 3, are the same. 



Here, as on the Psah River, pieces of lignite are occasionally found disseminated 

 in bed No. 4, but never any regular bed of this mineral. Some of it has the appear- 

 ance of lignite or carbonized wood, some of inferior cannel coal. The reports of 

 the existence of an important coal basin in this vicinity have, I believe, no better 

 foundation than the existence of transported pieces of this coaly substance in the 

 drift formation found at the head of the southern tributaries of the St. Peter's. 

 These pieces may either have been derived partly from the denudation of some of 

 the northern seams of coal of the Iowa coal-field, or of the lignite formation lying 

 to the west, which Mr. Evans traced high up on the Missouri, and which probably 

 extends some distance east of that river. 



The species of fresh-water shells found in bed No. 5, are such as occur in the 

 neighbouring streams and lakes, viz. : Planorbis parvus and bicarinatus, Paludina, 

 decisa, Lymnea columella, Physa heterostropha, (?) TJnio siliquoides, Melania Virginica, (?) 

 and an undetermined species of Cyclas. 



Bed No. 7 contains both fresh-water and land shells similar to those found in the 

 white shell marl, near the Falls of St. Anthony. The principal species are : Val- 

 vata tricarinata, Helix striatella, H. alter nata, H. arborea, Planorbis parvus, and Pla- 

 norbis hicarinatus, Paludina Mimosa, Lymnea columella, and undetermined species of 

 Ancylas and Cyclas. 



* The analysis which I made of the ash-coloured clay yielded as follows : 



Carbonate of lime, ....... 14-2 



" magnesia, ...... 6*0 



Insoluble matter, ....... 65- 



Alumina, oxide of iron, and manganese, .... 4-4 



Water, ........ 9-2 



Loss, ......... 1-2 



1000 



02 



