90 NEW YORK STATE MUSEUM 



the Paleozoic rocks assigned above on this Potsdam would leave 

 none of the present peaks projecting above the general level." 

 Again he stated:^ "This submergence (Utica) apparently com- 

 pletely overswept the old Adirondack island, and that for the first 

 time in its paleozoic history, with the possible exception of the latter 

 part of the Trenton." 



Still later the writer,^ speaking of the Paleozoic sediments along 

 the southwestern border of the Adirondacks, said : '' This thick- 

 ness (fourteen hundred feet) is great enough so that even after 

 allowing for decreased thickness due to overlap and a possibly in- 

 creased slope (receiving sediments) as the heart of the Adirondacks 

 was approached, we seem to have here a strong argument in favor of 

 the submergence of the region for many miles to the east and north- 

 east of Port Leyden, so that by the close of the Lower Siluric 

 (Ordovicic) the submergence extended to, or close to, the heart of 

 the Adirondacks." 



This line of reasoning, however, does not regard the possible 

 importance of downwarping troughs of deposition. As already 

 shown in this paper, such troughs of deposition clearly did exist 

 from Potsdam through Trenton time and we have no good reason 

 to doubt their existence during Utica and late Ordovicic time as 

 well. In a recent paper Gushing* says : "As the evidence accumu- 

 lates it points more and more strongly to deposit in downwarping 

 troughs, in which large depth of deposit by no means implies ex- 

 tensive overlap on the shores. . . . Even when submerged at the 

 same time, as in the Trenton, the deposits on the two sides (east 

 and west) are so different both lithologically and faunally, as to 

 indicate that the two basins had no very direct connection." 



Some years ago Ruedemann,^* by noting the parallel positions of 

 the graptolites in the black shales at Wells, Dolgeville (Herkimer 

 county), along Nine Mile creek near Trenton Falls (Oneida 

 county), etc., proved the existence of a late Ordovicic ocean current 

 across the southern side of the Adirondack region. The proof for 

 the existence of such an ocean current by no means implies that it 

 swept entirely across the whole Adirondack region, and hence we 

 have here no argument for a complete submergence of the region 

 at that time. In fact Ruedemann gives good reason for the belief 



3 Page 285. 



4 Page 144. • 

 9 Page 43. 



" Pages 367-91 and ^^ Pages 75-81. 



