408 PROCEEDINGS OF WASHINGTON MEETING. 



The following paper was illustrated by lantern views : 



PHYSIOGRAPHY OF THE EASTERN ADIRONDACKS IN THE CAMBRIAN AND 



ORDOVICIAN PERIODS 



BY J. F. KEMP 



Contents 



Page 



Introduction 408 



Geology of the Champlain region 408 



Interpretation of the geology and statement of the problem 408 



Previous work bearing on the problem? 409 



Influence of limestones on the topography 409 



Keeseville embayment 409 



Willsboro-ISssex embayment 410 



Westport embayment 410 



Port Henry embayment 410 



Resume 410 



Crown Point-Schroou Lake embayment 410 



Ticonderoga embayment 411 



Other outliers 412 



Conclusion 412 



Alternative hypothesis •. 412 



Introduction 



The waters of lake Champlain lie in a depression, whose eastern boundary, except 

 for a short distance at its southern extremity, is made up of Paleozoic strata. The 

 larger part of the western shore is also composed of the same formations, but in 

 many places the pre-Cambrian crystallines jut out in ranges of hills to the water's 

 edge, and at all points south of Port Kent they are not far back from the lake. 



The relations of the Paleozoic strata to the crystallines furnish some interesting 

 data regarding the physiography of what maybe most fittingly called the "Adiron- 

 dack island " of early Paleozoic time. 



Geology of the Champlain Kegion 



The researches of several observers, of whom the latest and most important is 

 C. D. Walcott, have shown the presence of the Lower, Middle, and Upper Cam- 

 brian strata in Vermont. The Lower and Middle Cambrian do not cross the lake, 

 for the Upper Cambrian or Potsdam, in the form of conglomerates and sandstones, 

 the latter vastly predominating, is the oldest Paleozoic and unmetamorphosed 

 formation present on the New York shore. Prolonged and careful search has been 

 made by several observers, including the writer, in order to test this statement, but 

 thus far no facts have been found to modify it. Conformably on the Potsdam the 

 Calciferous, Chazy, Trenton, and Utica formations follow,. but none later than the 

 Utica have been recorded except the Glacial and post-Glacial drift, sands, and clays. 



Interpretation of the Geology and Statement of the Problem 



It is evident from the above that the Lower and Middle Cambrian strata were 

 laid down well to the east of the present limits of the crystallines, and that with 

 their gradual subsidence the Cambrian sea crept westward, so that the Potsdam 



