360 POPULAR SCIENCE MONTHLY. 



The continuation of the Hudson River Valley has been traced 

 by detailed hydrographic surveys to the edge of the steep conti- 

 nental slope at a distance of about one hundred and five miles 

 from Sandy Hook. Its outermost twenty-five miles are a sub- 

 marine fiord three miles wide and from 900 to 2,250 feet in verti- 

 cal depth measured from the crest of its banks, which with the 

 adjoining flat area decline from three hundred to six hundred feet 

 below the present sea level. The deepest sounding in this fiord is 

 2,844 feet. An unfinished survey by soundings off the mouth of 

 Delaware Bay finds a similar valley submerged nearly twelve 

 hundred feet, but not yet traced to the margin of the continental 

 plateau. Again, the United States Coast Survey and British 

 Admiralty charts, as Spencer states, record submerged fiord out- 

 lets from the Gulf of Maine, the Gulf of St. Lawrence, and Hud- 

 son Bay, respectively 2,664 feet, 3,666 feet, and 2,040 feet below 

 sea level. The bed of the old Laurentian River, as the preglacial 

 St. Lawrence is named by Spencer, from the outer boundary of 

 the Fishing Banks to the mouth of the Saguenay, a distance of 

 more than eight hundred miles, is reached by soundings 1,878 to 

 1,104 feet in depth. Advancing inland, the sublime Saguenay 

 fiord along an extent of about fifty miles ranges from three 

 hundred to eight hundred and forty feet in depth below the sea 

 level, while in some places its bordering cliffs, one to one and a 

 half miles apart, rise abruptly fifteen hundred feet above the 

 water. 



On the Pacific coast of the United States Prof. Joseph Le 

 Conte has shown that the islands south of Santa Barbara and Los 

 Angeles, now separated from the mainland and from each other 

 by channels twenty to thirty miles wide and six hundred to one 

 thousand feet deep, were still a part of the mainland during the 

 late Pliocene and early Quaternary periods. In northern Cali- 

 fornia Prof. George Davidson, of the Coast Survey, reports three 

 submarine valleys about twenty-five, twelve, and six miles south 

 of Cape Mendocino, sinking respectively to 2,400, 3,120, and 2,700 

 feet below the sea level, where they cross the hundred-fathom 

 line of the marginal plateau. If the land there were to rise one 

 thousand feet, these valleys would be fiords, with sides towering 

 high above the water, but still descending beneath it to profound 

 depths. Le Conte has correlated the great epeirogenic uplifts of 

 North America, known by these deeply submerged valleys on 

 both the eastern and western coasts, with the latest time of oro- 

 genic disturbance by faulting and upheaval of the Sierra Nevada 

 and Coast Range in California during the closing stage of the Ter- 

 tiary and the early part of the Quaternary era, culminating in the 

 Glacial period. In the Mississippi basin, from the evidence of 

 river currents much stronger than now, transporting Archsean 



