194 MAN AND THE GLACIAL PERIOD. 



ica at the beginning of the Glacial period. The direct 

 proof of this preglacial elevation is largely derived from 

 the fiords and great lake basins of the continent. The 

 word " fiord " is descriptive of the deep and narrow inlets 

 of the sea specially characteristic of the coasts of Norway, 

 Denmark. Iceland, and British Columbia. Usually also 

 fiords are connected with valleys extending still farther 

 inland, and occupied by streams. 



Fiords are probably due in great part to river erosion 

 when the shores stood at considerably higher level than 

 now. Slowly, during the course of ages, the streams wore 

 out for themselves immense gorges, and were assisted, per- 

 haps, to some extent by the glaciers which naturally 

 came into existence during the higher continental eleva- 

 tion. The present condition of fiords, occupied as they 

 usually are by great depths of sea-water, would be ac- 

 counted for by recent subsidence of the land. In short, 

 fiords seem essentially to be submerged river gorges, par- 

 tially silted up near their mouths, or perhaps partially 

 closed by terminal moraines. 



It is not alone in northwestern Europe and British 

 Columbia that fiords are found, but they characterize as 

 well the eastern coast of America north of Maine, while 

 even farther south, both on the Atlantic and on the Pa- 

 cific coast, some extensive examples exist, whose course 

 has been revealed only to the sounding-line of the Gov- 

 ernment survey. 



The most remarkable of the submerged fiords in the 

 middle Atlantic region of the United States is the con- 

 tinuation of the trough of Hudson River beyond New 

 York Bay. As long ago as 1844 the work of the United 

 States Coast Survey showed that there was a submarine 

 continuation of this valley, extending through the com- 

 paratively shallow waters eighty miles or more seaward 

 from Sandy Hook. 



The more accurate survevs conducted from 1880 to 



