346 Warren Upham — Pleistocene Climatic Changes. 



regions, this may be properly named the epeirogenic theory of the 

 Ice-age.' Condensed into a single paragraph, it shows in the fjords 

 and submarine continuations of river valleys a proof that the drift- 

 bearing areas immediately before the accumulation of the ice-sheets 

 had been gradually elevated thousands of feet, until finally the cool 

 plateau climate at the culmination of the uplift brought on the 

 Glacial period ; in the low condition of the lands, when the Drift 

 was left by the retreat of the ice, it sees that these areas had sunk 

 beneath their ice- weight, until mostly they stood somewhat below their 

 present level; and in the post-G-lacial uplift of the marine Champlain 

 deposits, overlying coastal portions of the Glacial drift, it sees an 

 effort of the earth to regain a state of simple flotation of the crust 

 on the heavier mobile interior which is capable of flow whether it 

 be solid or molten. 



The epeirogenic movements of the countries which became 

 glaciated were only a portion of widespread oscillations of conti- 

 nental areas during the closing part of Tertiary time and the ensuing 

 much shorter Quaternary area. Not only were the northern half 

 of North America and the north-western part of Europe uplifted 

 1000 to 3000 feet or more, but probably all the western side of 

 Europe and Africa shared in this movement, of which we have the 

 most convincing proof ia the submerged channel of the Congo, 

 about four hundred miles south of the Equator. From soundings 

 for the selection of a route for a submarine cable to connect 

 commercial stations on the African coast, Mr. J. Y. Buchanan^ found 

 this channel to extend eighty miles into the ocean to a depth of 

 more than 6000 feet. The last twenty miles of the Congo have a 

 depth of from 900 to 1450 feet. At the mouth of the river its width 

 is three miles and its depth 2000 feet. Thirty-five miles ofi' shore 

 the width of the submerged channel or canon is six miles, with a 

 depth of about 3450 feet, its bottom being nearly 3000 feet below 

 the sea-bed on each side. Eifty miles from the mouth of the river 

 the sounding to the submarine continental slope is nearly 3000 feet, 

 while the bottom of the old channel lies at 6000 feet. This very 

 remarkable continuation of the Congo Valley far beneath the sea- 

 level is like those of the Hudson and St. Lawrence rivers, and like 

 numerous submerged valleys on the coast of California ; but the 

 Congo reaches to a greater depth than those of North America, and 

 even exceeds the Sogne fjord, the longest and deepest in Norway, 

 which has a maximum sounding of 4080 feet. Another deep sub- 

 marine valley, called the " Bottomless Pit," having soundings of 

 2700 feet, is described by Buchanan on the African coast 350 miles 

 north of the Equator, and he states that a similar valley exists in 

 the southern part of the Bay of Biscay. These observations show 

 that within very late geologic time probably almost the entire 



' The terms epeirogeny and epeirogenic ("continent-producing," from the Greek 

 epeiros, a mainland or continent) are proposed by Mr. G. K. Gilbert in his U.S. Geol. 

 Survey Monograph, Lake Bonneville (1890), to designate the broad movements of 

 uplift and subsidence which affect the whole or large portions of continental areas 

 or of the oceanic basins. 



^ Scottish Geographical Magazine, vol. iii. 1887, pp. 217-238. 



