Geology . Fig. 489.—Diagrammatic representation of a hill unworn by the ice. The diagramalso shows the irregular contact between the surface earths and the rock below. referred to, the rock hills of many localities over which the ice passedwere systematically worn more on the side from which the ice approached(the stoss-side), than on the other (Fig. 490). Bosses of rock. ^^^^^^^^^^^^^^B Fig. 490.—Diagram to show the effect of glacial wear on such a hill as that shown in Fig. 488. which do not show pronouncedly unequal wear often show dis-tinctive smoothing (Fig. 491). Projecting glaciated kno
Geology . Fig. 489.—Diagrammatic representation of a hill unworn by the ice. The diagramalso shows the irregular contact between the surface earths and the rock below. referred to, the rock hills of many localities over which the ice passedwere systematically worn more on the side from which the ice approached(the stoss-side), than on the other (Fig. 490). Bosses of rock. ^^^^^^^^^^^^^^B Fig. 490.—Diagram to show the effect of glacial wear on such a hill as that shown in Fig. 488. which do not show pronouncedly unequal wear often show dis-tinctive smoothing (Fig. 491). Projecting glaciated knolls of rock,whether large or small, which show the characters seen in Fig. 492,are known as roches moutonnees. A succession of roches moutonneesgenerally give fairly accurate information as to the direction of icemovement, even though striae be not preserved. Summary.—The characteristics of the drift, as set forth in thepreceding paragraphs, leave little room for random speculationconcerning its origin. From its variable thickness we know that theforce or forces which produced it must have been such as could leavethe drift now in thick bodies and now in thin, over either limited orextensive areas. From its distribution we know that the force orforces which produced it were largely independent both of underlying 01 OLOOY.
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