424 GEOLOGY OF THE SECOND DISTRICT. 



2. The surface has been depressed, and rivers have coursed far and wide over land which is 

 now elevated, and upon which none are now found. Proof of this is furnished in the numerous 

 pot-holes in ledges of rock now distatit from any stream, and far above all the creeks in the 



region. 



3. There are long lines of gravel and sand in the form of ridges, which mark distinctly tht- 



former borders of lakes or seas. 



4. The existence of the tertiary, a marine formation, now reclaimed by elevation, not by 

 depression, or by the wearing down of barriers. 



The hypothesis of wide shallow rivers answers better to existing phenomena than any other. 

 We require running water, with a current capable of pushing along gravel and sand, for it is 

 only by means of fine materials that we can obtain a smooth polished surface ; and it is essen- 

 tial, too, that it should be borne along in one given direction for a long time, as in forming or 

 channelling the deep grooves in the birdscye at Watertown (see Fig. 90, p. 3G9.) 



Wherever 1 have observed these deep scorings, I have felt the necessity of calling in the aid 

 of runnino- water. Neither icebergs nor glaciers arc at all fitted to produce phenomena of this 

 kind or character, though they may scratch rocks ; the latter especially must be ranked among 

 the agents which produce this effect, but icebergs are among the more unimportant of those 

 agents, and can by no means occupy a distinguished place as such in general. 



Subsequent to this period when broad shallow rivers flowed over our land, it became sub- 

 merged, and continued beneath the water of the ocean sufficiently long for the deposition of the 

 tertiary. During this period, the free and open communication with the Arctic ocean permitted 

 the ingress of icebergs, bearing the boulders of the north, the hypersthene rock, etc. ; these 

 stranded in the shallow waters which surrounded the central part of the now mountainous region, 

 that of the Adirondacks. This condition, however, did not continue; the whole country was 

 again elevated, and that not once for all, but by several successive upheaves, each followed 

 by a long interval of rest ; for we find tlie impressions of many different lines of coast, which 

 serve to distinguish the periods of activity of the elevating force from those of its repose. 

 This force was not violent, but it affected a wide extent of country : it was paroxysmal in its 

 operation, and generally produced but a moderate degree of derangement in the region sub- 

 jected to its influence ; but occasional fractures were made, and surfaces which were previously 

 marked by diluvial action, were disjoined, as may now be frequently observed in the valley 

 of Lake Champlain. During the period when the tertiary was depositing, we have reason to 

 believe that the space occupied by the great lakes was greatly enlarged ; and that those de- 

 pressions which had been made by large streams flowing through the shales of Jefferson county, 

 were extended laterally by the action of waves. 



The above hypothesis may appear complicated and unsatisfactory, and to some it mSy not 

 appear why I have supposed the fluvialilc era should precede the marine. I remark, that this 

 is essential ; for the scorings of the rocks cannot have taken place since the marine era : 

 they must have been made previous to the deposition of the tertiary, and the whole country 

 has since been submerged, and afterwards raised and reclaimed. Tbe groovings leading from 

 Watertown to Lake Ontario must have also been made before the tertiary deposit ; and the 



