EPEIROGENIC MOVEMENTS EFFECT ON ICE AGE 7 



elevation of the country along an areal extent surpassing that revealed south of 

 cape Mendocino by soundings. 



INTERIOR OF NORTH AMERICA 



In the Mississippi basin, from the evidence of river currents much stronger 

 than now, transporting Archean pebbles from near the sources of the Mississippi 

 to the shore of the gulf of Mexico, Professor E. W. Hilgard thinks that the prer 

 glacial uplift, inaugurating the Ice age, was 4,000 to 5,000 feet more in the central 

 part of the continent than at this river's mouth* 



ATLANTIC BORDERS OF THE UNITED STATES AND CANADA 



On the east side of our continent, its bordering submarine plateau, much wider 

 than on our Pacific coast, is cut by submerged valleys, which, if raised above the 

 sealevel, would be fiords or canyons. These can be no other than river-courses 

 eroded while the land stood much higher than now ; and its subsidence evidently 

 took place in a late geologic epoch, else the channels would have become filled with 

 sediments. Their most instructive example is the continuation of the Hudson 

 Elver valley, which has been traced by detailed hydrographic surveys to the edge 

 of the steep continental slope at a distance of about 105 miles from Sandy Hook. 

 Its outermost 25 miles are a submarine fiord 3 miles wide and from 900 to 2,250 feet 

 in vertical depth measured from the crests of its banks, which with the adjoining 

 flat area decline from 300 to 600 feet below the present sealevel. The deepest 

 sounding in this fiord is 2,844 feet.f 



Again, as noted by Spencer, the United States Coast Survey and British Ad- 

 miralty charts record submerged outlets from the gulf of Maine, the gulf of Saint 

 Lawrence, and Hudson bay, respectively 2,664 feet, 3,666 feet, and 2,040 feet below 

 sealevel. t The bed of the old Laurentian river from the outer boundary of the 

 Fishing banks to the mouth of the Saguenay, a distance of more than 800 miles, is 

 reached by soundings 1,878 to 1,104 feet in depth. Advancing inland, the sub- 

 lime Saguenay fiord along an extent of about 50 miles ranges from 300 to 840 feet 

 in depth below the sealevel, whil? in some places its borderings cliffs, 1 to li miles 

 apart, rise abruptly 1,500 feet above the water. 



ARCTIC AMERICA AND GREENLAND 



The islands of the Arctic archipelago are separated from each other by wide 

 and deep valleys of subaerial erosion, and their shores, as well as that of Labrador 

 and all the coastline of Greenland, west, east, and north, are cut by fiords mostly 

 1,000 to 1,500 feet deep. The maximum known sounding of these partly sub- 

 merged valleys was reported by Koldewey in the Franz Josef fiord of eastern 

 Greenland, where no bottom was found at 3,000 feet. 



WESTERN EUROPE AND WESTERN AFRICA 



The fiords and submerged valleys of the British isles and of Scandinavia show 

 that the drift-bearing northwestern part of Europe stood in preglacial time 1,000 



*Am. Jour. Sci., third series, vol. xliii, pp. 389-402, May, 1892. 



f A. Lindenlvohl : Beport of tlie U. S. Coast and Geodetic Survey for 1884, pp. 435-438 ; Am. Jour. 

 Sei., third series, vol. xxix, pp. 475-480, June, 1885. James D. Dana, Am. Jour. Sci., third series, 

 vol. xl, pp. 425-437, Dec, 1890, with an excellent map of the Hudson submerged valley and fiord. 



J Bull. Geol. Soe. Am., vol. i, 1890, pp. 05-70, with map of the preglacial Laurentian river (also in 

 the Geol. Magazine, tliird decade, vol. vii, 1890, pp. 208-212). 



