associated with Glaciation. . 117 



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 

 6,000 feet. The last twenty miles of the Congo have a depth 

 from 900 to 1,150 feet. At the mouth of the river its width 

 is three miles and its depth 2,000 feet. Thirty-five miles off 

 shore the width of the submerged channel or canon is six 

 miles, with a depth of about 3,450 feet, its bottom being 

 nearly 3,000 feet below the sea bed on each side. Fifty miles 

 from the mouth of the river the sounding to the submarine 

 continental slope is nearl} 7 3,000 feet, while the bottom of the 

 old channel lies at 6,000 feet. This very remarkable continua- 

 tion 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 these of North America, and 

 even exceeds the Sogne fjord, the longest and deepest in Nor- 

 way, which has a maximum sounding of 1,080 feet. Another 

 deep submarine valley, called the " Bottomless Pit," having 

 soundings of 2,700 feet, is described by Buchanan on the Afri- 

 can 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 Atlantic side of the eastern conti- 

 nent has been greatly uplifted, attaining as high an altitude as 

 that which A. C. Ramsay and James Greikie . conjectured as a 

 possible cause of the frost-riven limestone- agglomerates of 

 Gibraltar, f 



Likewise the tropical portions of the western continent, the 

 West Indies, and the smaller islands of the Caribbean region, 

 appear to have shared the epeirogenic disturbances which were 

 associated with the glaciation of the northern and southern 

 parts of this continent, as is well brought out by the recent 

 studies and discussions of the geology of Barbados island by 

 A. J. Jukes-Browne and J. B. Harrison,:}: and by the close 

 relationship of the Pacific and West Indian deep sea faunas on 

 the opposite sides of the Isthmus of Panama, made known 

 through dredging by Alexander Agassiz.^ This testimony, 

 indeed, with that of Darwin, L. and A. Agassiz, and others, 

 of very recent, extensive, and deep subsidence of the western 



* Scottish Geographical Magazine, vol. hi. 1887, pp. 217-238. 

 f Quart. Jour. Geol. Soc, vol. xxxiv, 1878, pp. 505-541. 

 % Quart. Jour. Geol. Soc. vol. xlvii, 1891, pp. 197-250. 



§ Bulletin Mus. Comp. Zool. at Harvard College, vol. xxi, pp. 185-200, June, 

 1891. 



