and Disturbed Stratification. — 381 
till or till-ecovered rock in which ease they constitute unsym- 
metrical embossments of varying forms. 
Angular gravel, natural size; from a hillock one mile north of Midway, Madison 
County, Ohio, 
up chiefly of gravel 
and subordinately of sand, clay and bowlders. Special in- 
by forceful rubbing rather than rolling. There are not infre- 
other portions, till from which most of the clay has been re- 
Moved ; still other portions consist of the rock-fragments of. 
the till with a meagre amount of clay in the interstices ; while 
yet other portions consist of the subangular gravel above de- 
scribed, quite thoroughly separated from the clay and slightly 
* The illustrative examples are here described, not the whole class. 
