4 Spencer — Great Canyon of the Hudson River. 



depth. From the soundings beyond the deep point, he at first 

 thought a bar of 1600 feet in height crossed the month of the 

 canyon. 



In 1889, 1 pointed ont that this canyon, along with those at 

 the mouth of the Gulf of St. Lawrence and of the Maine, could 

 be taken as yardsticks in measuring the late continental eleva- 

 tion to the extent of 3000-3600 feet. This was in the second 

 paper published by the Geological Society of America, the 

 first being by Prof. Dana.* 



A few months later Dr. Warren Upham cited the Hudson 

 canyon among the evidence he brought together to show that 

 elevation was the cause of the glacial period. f In it he attrib- 

 uted the apparent bar to the action of coastwise wave-wash 

 during the subsidence of the continent after the formation of 

 the gorge. Though this bar was a large order for wave action, 

 it was the only reasonable explanation of the deep hole if such 

 it were, as suggested by the Coast Survey chart. 



Again in 1890, Prof. Dana published a paper,:}; in which he 

 says that the channel " affords strong evidence of the river 

 origin and therefore the whole channel up to JSTew York was 

 once the course of the Hudson." In the last edition of his 

 Manual he further says (page 948) that the former emergence 

 of the continental border now sunken is proved by the Hud- 

 son submerged valley, citing also the cases of the canyons of 

 the gulfs of St. Lawrence and Maine, mentioned above, as evi- 

 dence of the elevation of the region in the glacial period to at 

 least 3000 feet. It may be here stated that Prof. Dana, on 

 seeing my account of the submarine valleys of the West Indian 

 region, wrote to Prof. Lindenkohl, who replied that he was not 

 aware of them, and hence the note in his Manual concerning 

 them (page 949). Prof. Lindenkohl, however, later accepted 

 my interpretation of the much deeper valleys§ which Dana 

 doubted, confirmed by Prof. Lindenkohl's want of knowledge 

 at the time, though Prof. Dana accepted my St. Lawrence can- 

 yon to 3600 feet below sea level. 



In 1897 I read a paper before the British Association, stat- 

 ing that with the very insufficient soundings, the Hudsonian 

 valley was recognizable to a depth of 12,000 feet. || illus- 

 trating how we may anticipate where canyons may be found. 

 This paper, amplified into " The Submarine Valleys off the 



* • ' The High. Continental Elevation preceding the Pleistocene Period," Bull. 

 Geol. Soc. Am., vol. i, pp. 65-70, 1890. 



f Bull. Geol. Soc. Am., vol. i, p. 563. Also Geol. Mag. Lond. (3), vol. vii, 

 p. 494, 1890. 



^''Long Island Sound in the Quaternary era, with Observations on the 

 Submarine Hudson River Channel," this Journal (3), vol. xl, p. 425, 1890. 



§Bull. Geol. Soc. Am., vol. xiv, p. 226, 1903. 



|| lb., pp. 207-226. 



* 





