1880.] 431 [Stone. 
varying from near 2000 feet on the west, to less than 1000 on the 
east; and its average slope per mile is at least seven feet. This 
slope is favorably situated for the precipitation of moisture, the 
annual rainfall being about forty-four inches, and it must have been 
a region of great precipitation in the glacial period, especially during 
summer. ‘This would tend to swell the torrents of the melting ice- 
sheet, and the steepness of the slope would give them great swift- 
ness and power of transportation. The rocks of the southern slope 
are mainly crystalline, or highly indurated. Although the general 
slope is southward or south-eastward, yet the map shows that all the 
longer streams flow eastward or westward for a considerable part of 
their course, deflections which are usually caused by east and west 
ranges of hills. The main mountain region crosses the State north- 
eastwardly in a nearly straight line from the White Mountains, past 
Mt. Abraham and Mt. Katahdin, to Mars Hill, near the St. John 
River. South of this are three ranges of hills forming the southern 
limits of the valleys of the Sandy, the Piscataquis, and the Matta- 
wamkeag Rivers, which ranges are so nearly in a straight line as to 
make it possible that they really are one system. Still further south 
is another east and west range of hills, separating the valleys of the 
Sebasticook and Soudabscook from those of the coast streams, the 
St. George’s, etc. This range reaches from near the Kennebec River 
to the Penobscot, where it connects with a series of hills extending 
north and east from Rockland, and the latter may in origin be a part 
of the irregular system of hills which extends from Mt. Desert north- 
eastward to the lakes of the upper St. Croix River. It will be con- 
venient to refer to the latter system as the Mt. Desert Highlands. 
These Highlands consist in considerable part of granite, which out- 
crops, with some interruption, all the way from Mt. Desert to Chaleur 
Bay on the Gulf of the St. Lawrence. Much of this granite is coarse 
and easily fractured, and everywhere the line of outcrop is marked 
by a great number of granite boulders. This is perhaps more notice - 
able in New Brunswick than in Maine. Besides those named, num- 
erous other minor ranges, trending eastward or north-eastward, are 
found, as well as a great number of isolated hills, not, however, of 
- great height. 
This arrangement of hills transverse both to the general slope and 
line of glacial flow must fave had an important effect on the move- 
ments of the great ice-sheet, particularly during the final melting. 
When the ice became less than 500 feet thick, over a large part of 
