180 SURFACE GEOLOGY. 
There is teason to believe that examples similar to the above exist by 
the hundred. They are not usually visible, except where excavations 
have been made. 
PLANISHING AND EMBOSSMENT. 
Should the earth be entirely removed from the ledges, the majority of 
them, save where subsequent erosion has obliterated the marks, would 
show upon their exposed sides a planing down and rounding. These 
ledges are not planed down fiat, like a floor, but are rounded, retaining 
essentially their original forms. It is a common sight, when travelling 
along the deeper valleys, to observe, above the line of the modified drift, 
numerous rounded, dome-shaped ledges. A close scrutiny will disclose 
the fact that these have been worn the most upon the northern side, 
while the southern escarpment may be rough and uneven. Hence it is 
obvious from which direction the force proceeded which planed down the 
ledges. The sides most worn are those which have been struck. We 
often speak of the struck or s¢oss and the dee sides of these rounded ledges. 
The embossed ledges are often grouped in considerable numbers, 
looking as if there were an assemblage of haystacks closely crowded 
together. Precisely similar phenonena occur in the glaciated region of 
FG. 50.—EMBOSSED Rocks ON Mt. MONADNOCK. 
the Alps, where De Saussure applied to them the name of voches mou- 
tonnes. An example of them, as seen in New Hampshire, is given in 
