Report on the Geology of Clinton County. 



By H. P. Cushing. 



Contents. Introduction, p. 503. Topography, p. 504. General Geologic Relations, p. 50(5: 

 I. Gneissic Series, p. 506 ; II. Limestone Series, p. 508 ; III. Gabbro Series, p. 508 ; IV. Palaeozoic Series, 

 p. 510; Potsdam Sandstone, p. 510; Calciferous Sandrock, p. 512; Chazy Limestone, p. 513; Black 

 River Limestone, p. 514; Trenton Limestone, p. 514; Utica Slate, p. 515; V. Dike Series, p. 515; 

 VI. Pleistocene Deposits, p. 527. Metamorphism of the Pre- Cambrian Rocks, p. 529. Post-Ordovician 

 Disturbances, p. 530; Township Geology, p. 531: Clinton Township, p. 532; Mooers Township, p. 532; 

 Ellenburgh Township, p. 533; Daunemora Township, p. 535 ; Saranac Township, p. 538 ; Black 

 Brook Township, p. 541 ; Ausable Township, p. 545; Peru Township, p. 549; Schuyler Falls Town- 

 ship, p. 552; Plattsburgh Township, p. 553 ; Beekmantown Township, p. 551); Altona Township, 

 p. 562 ; Chazy Township, p. 562 ; Champlain Township, p. 571. 



The field work the general results of which are [(resented in this 

 report, w as done during the Held seasons of 1 893— '94— 95, about four weeks 

 during each being devoted to the work. On the last two occasions, Mr. M. 

 L. McBride, of Cleveland, at his own expense, accompanied the writer as 

 assistant and rendered valuable service. During 1895, a week was spent with 

 Messrs. Gilbert van Ingen and T. Gr. White, of Columbia College, in inspecting 

 the best exposures of the Ordovician limestones in the county, and Mr. van 

 Ingen's palaeontologic ability was of great service in making clear some 

 perplexing points in the stratigraphy. 



The entire county has been traversed and mapped, but only in a general 

 way, the desideratum being the acquisition of a good general know ledge of 

 the district before attempting the detailed work which will be necessary for 

 the proper elucidation of the perplexing problems which have arisen. 

 Furthermore, no good, or even fair maps exist of the greater part of the 

 county, so that, until such are available, it is useless to attempt closer w ork. 

 A beginning has, however, been made in the detailed mapping of the 

 palaeozoic rocks along lake Champlain, which is necessary in order to fully 

 bring out the structural features, and it is the present expectation t<» con- 

 tinue this' as opportunity offers. 



Since the report of Professor Emmons, over fifty years ago, practically 

 nothing has been published on the geology of the county except the 

 beautiful bits of mapping and sectioning done by President Brainard and 



503 



