14 GEOLOGY OF THE SECOND DISTRICT. 



as quite recent, and, in addition to this, as having undergone but httle change since the marine 

 occupants gave place to the lacustrine. 



On the New-York side there are several small and unimportant valleys which open into the 

 Champlain ; the most important are those of Lake George, which has already been spoken 

 of as extending to the plains of Saratoga, the Bouquet, Ausable and Saranac. The Bouquet 

 is narrow, and runs nearly in the direction of the lake about eight miles, and along the junction 

 of the primarj- with the lran.-;ition rocks. The Ausable is much more important, and is geo- 

 logically interesting for the gorges in the Potsdam sandstone through which the Ausable flows. 

 The river flows near the southeastern side of this valley, and it is not improbable but it would 

 be proper to consider the Ausable and iSaranac as but one valley. Considered as one, it ex- 

 tends twenty miles west of the lake, and north till it terminates in the valley of the St. Law- 

 rence. It lies in the angle formed by the Great Adirondack on the south, and Lyon and 

 Whiteface on the west and northwest. It extends therefore from Keeseville to Champlain, 

 and from Plattsburgh to lledford. Geologically, this valley is important and interesting, par- 

 ticularly as it furnishes a better developement of the lower transition rocks than any other 

 part of the State. It is only here that we find the series complete ; the phenomena too of uplifts 

 and fractures are finely displayed ; in addition to which, all the elementary principles of 

 geology may be found illustrated in a field quite accessible. 



I have only to notice one other feature in the valley of the Champlain, viz. the obliquity of 

 of its subordinate valleys. Thus, on the west or New-York side they open to the northeast ; on 

 the east, nearly to the northwest ; though as it regards the latter, their course coincides more 

 nearly with the direction of the Green Mountain range ; thus, the valley of Otter creek coincides 

 very nearly with that of the lake, or to a north and south direction. These facts, it is true, are 

 unimportant in themselves, and they are only noticed for the purpose of showing more clearly 

 the slope and convergences of the valley; it is only by these facts that this structure can be 

 demonstrated. 



Age of the Valley of the CJiamplain. — The question concerning the age of valleys is quite 

 as important as that of the mountain system ; in many instances these two inquiries are con- 

 nected and inseparable from each other, or the determination of one settles that of the other. 

 Though it is difEcuh to determine the question under consideration with much exactitude, still 

 there arc two or three facts which arc important : 1st, It is a very ancient valley, a fact which 

 is proved by the Organic remains of the clays and sands whicii form the present floor of the 

 valley. 2d, By the smooth and polished surface of the rocks which compose the ancient floor 

 upon which the clays and sands of the post-tertiary, (as the formation has been designated,; 

 were deposited ; for we cannot regard them as having been wholly formed by sudden and vio- 

 lent movements of the loose materials upon the surface : the whole phenomena is one of 

 moderate force, combined with one of power, but yet of long continuance. 



The ancient floor of this valley is formed by two classes or systems of rocks : 1st, The 

 primary, principally gneiss ; and 2d, the lower transition or rocks of the Champlain group, 

 as they are denominated in the subsequent pages. The order of events c6nnected with the 



