Agassis at Penilwse. 



67 



terrupt tlio onward progress of the groat ice-sheet, 

 nor even to deflect it from its course. On the shores 

 of Lake Winnipiseogee we rind bowlders identical 

 with those to the north of the White Mountains, 

 which shows that those mountains were not suffi- 

 cient to interrupt or dellect the onward motion of 

 the glacier. 



The numerous lakes and ponds or lakelets which 

 abound in the drift latitudes are a peculiar and one 

 of the most characteristic features of American 

 drift. The lakes of New- York may be taken as 

 typical examples of the lakes produced by our North 

 American glacier. 



The facts are these : The lakes trend N. S., being 

 elongated in this direction ; they have been cut out 

 of the solid rock ; their bottoms and sides are scored 

 and grooved in a N. S. direction ; along their mar- 

 gins are lateral moraines; about their southern 

 ends are numerous concentric terminal moraines, 

 and their inlets are at the southern and their outlets 

 at the northern ends. Lakes Ithaca and Cayuga 

 exhibit all these phenomena particularly well. 



The explanation is that these basins were exca- 

 vated by the terminal points of the glacier during 

 its retreat. The numerous terminal moraines Indi- 

 cate baitings and oscillations in the retreat. Many 

 of them are as distinct and moraine-like as any to 

 be seen in Switzerland to-day. Wherever the 

 southern margin of the ice-sheet was elongated into 

 points and capes during its retreat, these lateral 

 moraines were possible, such as we see bordering 

 these lakes. Curiously enough, the water now flows 

 in a direction directly opposite to that in which the 

 glacier moved. Substantially the same phenomena 

 are repeated in Maine and Minnesota. These New- 

 York lakes are probably synchronous with the fiords 

 of Maine. 



In the Northern Hemisphere the northern slopes 

 of the hills are most strongly marked by glacial 

 action, while in the Southern Hemisphere the re- 

 verse is true, and the southern slopes bear the 

 deepest im press of the moving ice. 



No evidence or indications of any kind are afforded 

 by nature showing that the glacial phenomena of 

 the two hemispheres were not synchronous. 



The theory of the Scotch astronomer, Croll, based 

 upon the precession of the equinoxes, from which 

 he concluded that the glaciation of the northern and 

 southern hemispheres must have been alternate as 

 to time, is wholly gratuitous, and does not account 

 for the totality of the phenomena. 



DRIFT PHENOMENA. 



American drift material contains no angular blocks 

 or bowlders such as are so characteristic of most of 

 the European drift. The reason of this is that the 

 American glacier had no lateral or medial moraines, 

 and the drift material was all formed under the 



glacier where it was impossible to escape abrasion. 

 American drift exhibits considerable variations, de- 

 pending on the kind of rocks over which the glacier 

 moved, and of which the drift is made. 



The north-southerly motion of the glacier tended 

 to form these different kinds of drift into bands and 

 lines running south from the rocks from which they 

 were derived. 



There are a number of such bands crossing the 

 State of Massachusetts, and they may be found 

 moi 9 or less distinct over the whole country. The 

 width of any band depends in great measure upon 

 the east-westerly extent of the rocks from which it 

 is derived. 



North of Richmond, Mass., are three ranges of 

 hills, trending in an east-westerly direction. Run- 

 ning south from these ridges are seventeen or more 

 parallel lines of drift. Some of the lines start from 

 the southern ridge, some from the middle and others 

 from the northern ridge, but they are all distinct and 

 separate. Tlio average length of these lines of drift 

 is twenty miles. This Richmond drift has been a 

 great trouble to all geologists ; utterly unintelligible, 

 uuexplaiuable by any other than the glacial hy- 

 pothesis. 



But the true explanation is simple enough. All 

 our drift is bottom drift. When the glacier passed 

 over the disintegrating summits of these Richmond 

 hills, the masses of rock became frozen into the 

 bottom of the glacier, and once in that condition 

 their transportation over the succeeding ridges was 

 a mere question of time, and they would be carried 

 in rectilnear, parallel courses from their points of 

 derivation until dropped by the melting or breaking 

 of the ice. 



Lyell, in his " Antiquity of Man," attempts to ex- 

 plain this Richmond drift phenomena. He attributes 

 the whole thing to icebergs, and his explanation in- 

 volves as complete a physical impossibility as can 

 be conceived. Beware of explanations made to suit 

 a particular case, especially when the explanation 

 requires an ocean that could not exist, and icebergs 

 that move as icebergs are never known to move. 



THE RANGE OF NORTH AMERICAN GLACIERS. 



Within the present precincts of glaciers we find 

 along their sides and terminations loose material 

 which in all cases is derived from the higher regions 

 from which the glacier came. Glaciers bring down 

 a variety of loose materials detached from the rocky 

 bed on which it rests. Lateral, terminal, medial, 

 and bottom moraines are absolute facts. The ter- 

 minal moraine is formed by the union of all the 

 other moraines at the foot of the glacier. It is a 

 miueralogical collection containing specimens of all 

 the rocks over which the glacier has passed. 



What can we make of that with reference to the 

 extent the great glacier injght have ran^.c-cl. an*! 



