STUDIES FOR STUDENTS 427 



3. Very crude sorting. 



4. Distributed in restricted areas, on or near steep slopes. 



5. Beds, if any are visible, dip in one general direction, though diverging. 



6. Beds, if any, may dip at high angles. 



7. Deposit varies in thickness, decreasing uniformly in direction of 

 divergence of dips. 



8. Material local and homogeneous lithologically. 



9. Pieces, angular. 



10. Fossils, if any, of terrestrial forms. 



1 1 . Surface and base of formation may have steep slopes. 



Figs. 4 and 5 show types of pluvial deposits, one in North Caro- 

 lina and the other at the foot of the Inyo Mountains in CaHfornia. 



CHARACTERS OF TALUS DEPOSITS 



Talus deposits are not abundant among sedimentary materials, 

 and yet they exist. At Ableman, Wis., a talus slope of Huronian 

 quartzite is included in Potsdam sandstone, and it is possible that 

 other conglomerates belong to this type of deposits. The char- 

 acters of these deposits are listed below. Fig. 6 shows a talus slope 

 of quartzite at Devils Lake, Wis. 



1. Coarse material greatly predominates over fine. 



2. Pieces are the result of mechanical disintegration. 



3. Pieces angular. 



4. No stratification. 



5. Distributed in restricted and isolated areas, or in very narrow belts 

 near high lands. 



6. Base and surface of formation have steep slopes. 



7. Pieces touch one another. 



8. Very porous. 



CHARACTERS OF GLACIAL TILL 



The characters of glacial till are so well known as to need no 

 discussion here. For the sake of getting the criteria together the 

 list is given. 



1. Heterogeneous in composition. 



2. High textural range (rock flour to enormous bowlders). 



3. Coarse material generally subordinate in amount to fine. 



4. No stratification. 



5. Constituents, largely subangular. 



6. Great variation in thickness within short distances. 



