474 FRANK CARNEY 
The present brief inquiry is confined to glacial sediments of the 
Pleistocene period. The conclusion arrived at, from a field study of 
these sediments in central New York and in northern and central 
Ohio, is that locally, at least, the alteration of a part of the drift is 
under way, that is, it has reached an appreciable stage of metamor- 
phism; furthermore, that this fact may be used in differentiating the 
drifts of some of the Pleistocene epochs. 
In this paper the term “metamorphism” includes all alterations 
concerned in the transition from degradational products to solid 
rock again.t' It is not possible to observe many stages in this cycle 
because of the fact that so far as present investigation goes, the glacial 
periods are separated by long lapses of time, and because of the further 
fact that most phases of metamorphism require a physical environ- 
ment that precludes observation. 
FIELD DATA 
The glacial deposits that occasioned this study are characterized 
by the following features: 
1. Color.—All the unmodified drift concerned is bluish; it is felt 
that this is the constant color of the deposits because the observations 
were made either along stream banks that were being undercut, 
thus giving fresh exposures, or along shore cliffs where the waves are 
undermining the drift. In most of the exposures the color condition 
is emphasized by contact with drift which differs in color; the usual 
association is a yellow and sometimes oxidized horizon of more 
recent glacial accumulation beneath which is the zone of bluish drift. 
So far as can be ascertained, the color is not dependent upon the 
content of the drift. The surfaces of the included bowlders, large 
and small, and the entire matrix of clay, are uniformly of a bluish 
cast. This characterization applies equally to these deposits in 
widely separated parts of Ohio as well as throughout a considerable 
region of central New York. Because of a lithological difference 
in the rock formations that were eroded, as shown by a study of the 
bowlders and pebbles in the drift, one would expect some variation 
in color; this, however, is not the case. 
2. Texture and structure.—As is the case with nearly all types of 
tC. K. Leith, Journal of Geology, Vol. XV (1907), p- 313- 
