Variability of the Earth’s climate - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 100

By contrast, deposits left by moving ice are not stratified:

''It is evident that ice is so nearly solid that the earthy material deposited by it
must be unassorted. The mud, sand, gravel, pebbles, and boulders, dragged along
underneath a moving stream of ice, must be left in an unstratified condition—the
coarse and the fine being indiscriminately mingled together. This is the character
of the extensive deposits of loose material that cover what we designate as a
glaciated region . [In such an] unstratified deposit, a variety of materials is

mingled that were derived from rocks both of the locality and from far-distant
regions. Moreover, the pebbles in this deposit are the most of them polished and
scratched after the manner of those which we know to have been subjected to
glacial action.''

...

Figure 2.46. Extent of the most recent ice age in North America (Chamberlain in Geike, 1894).