and Disturbed Stratification. 385 
mass of these hills, have not been analyzed, but acid tests in 
the field indicate the abundant presence of the carbonates. 
Two conditions of the clay may be recognized, linked by inter- 
mediate gradations. The one, in which it constitutes a matrix 
embracing the stony fragments after the manner of bowlder 
clay—indeed the mass is indistinguishable from pebbly till— 
the other, in which it is only a coating of the angular gravel, 
or a partial filling of its interstices, giving the impression that 
1t 18 a secondary inter-deposition. These two varieties are con- 
nected by intermediate gradations, giving rise to an interesting 
series of clayey gravels and gravelly clays. 
Cor tren 
37 
Fish 
Ve te 
: Raat ahs Sh catia, De: 
Section of a portion of a gravel hill, showing highly inclined and contorted 
oo nila Kast line of Sec. 28, T. XXI, R. 5 W., Jackson, Tippecanoe Co., 
jana, 
fectly represent the general aspect of the interior structure of 
these hillocks. To fully appreciate their real complexity, it is 
necessary that the study of the actual section should be carried 
into detail. 
It thus appears that these hills present gradations (1) of ma- 
terial from mixed stony clay nely assorted sand an 
gravel; (2) of attrition, from that of the glaciated till fragments 
