Submarine Valleys and Canons off American Coast 
features of the Gulf of St. Lawrence, and Gulf of Maine, and correlated them with those of the Hudson 
River, thus covering a wider field.1 The breadth of the Continental Shelf off the Carolinas and Florida, 
and other features among the Bahamas, have been surveyed by Mr. (now Admiral) Pillsbury and Professor 
A. Agassiz, but the study of submarine river-like valleys and cafions was not undertaken. 
My investigations in the Gulf of St. Lawrence were commenced in connection with the researches 
into the origin of the Great Lakes of America. These studies were subsequently extended to the 
Southern States and the West Indies, in order to determine what evidence of change of land and sea could 
be found there. I had the good fortune of investigating almost unstudied features, in a field where many 
soundings had been made for navigational and cable purposes, and these brought to light the most 
valuable scientific data. Besides these, I visited the West Indian Islands, Mexico, and Central America, 
for the purpose of examining the relation of the submarine valleys to the land features, while the region 
farther north was already familiar. The varied observations resulted in the systematic treatise entitled 
“Reconstruction of the Antillean Continent,” followed by many subsequent papers descriptive of local 
phenomena. These investigations, together with those of Professor Edward Hull,® on the eastern side of 
the Atlantic, and of Professor Fridtjof Nansen,‘ off the coast of Norway and in the Northern Seas, with 
his review of the subject, have now given rise to the study of a distinct branch of oceanography, of world- 
wide possibilities, which throws much light on the later history of the continents. 
The Hudsonian Cation and its Age-—The three most perfectly surveyed submarine cafions are those of 
the Hudson River,> the Congo,® and another off the island of Cape Verde. These latter two were 
surveyed in great detail on account of the breaking of the cables crossing them.’ But the origin of the 
Congo Channel was not then understood. It was later explained by Professor Hull and Dr. Warren 
Upham. 
The Hudson Cafion may be taken as a type. Soundings by the U.S. Coast Survey were made for 
the purpose of discovering the character of the “ holes” in the Hudson River extension. The results, as 
then known, were published by the writer in 1905.8 Additional soundings have since been made. 
From all of these it is seen that— 
In passing down New York Harbour the ancient Hudson Channel is buried by the sandbars which 
rise to within 20 or 30 feet of the surface, although it is now known that the gorge within its rocky 
walls, at New York City, reaches to more than 300 feet. In proceeding seaward, the sandbars are 
passed, and the partly refilled channel becomes apparent. Its bottom is composed of clay, while the 
surface of its banks is covered with sands. 
At 93 land miles from Sandy Hook, where the sea has a depth of 330 feet, the channel plunges 
into a chasm 800 feet deep. Here its direction is nearly eastward. Four miles beyond, it turns due 
south, and at this point are other falls aggregating 550 feet. After a farther distance of four or five 
miles still other falls of 600 feet occur, beyond which the trench again turns sharply eastward. From 
this point another stretch reaches for more than 15 miles, with a low gradient, and the soundings show 
subordinate windings. ‘The cafion crosses the border of the Continental Shelf, here arbitrarily defined 
at 500 feet below sea-level. Beyond, it trenches the Continental Slope with other great falls of 
2000 feet. Farther down the sharply winding gorge two falls of 1200 and goo feet occur. The 
maximum depth of the cafion reaches 4000 feet (where the Continental Slope is submerged only 1000 
feet). Its length is about 50 miles with the valley known for 25 miles farther. 
1 Bull. Geol. Soc. Am. vol. i. (1890). 
2 “ Reconstruction of the Antillean Continent,” cited before. 
8 Published in numerous papers by the Victoria Institute, 1898-1908. 
4 “Bathymetrical Features of the North Polar Sea.” One of the scientific monographs published by the Nansen Fund for the Advancement 
of Science. Christiania, 1904. 
5 Am. Ffourn. of Sci. vol. xix. pp. I-15 (1905). 
6 By J. Y. Buchanan, Scottish Geog. Mag. vol. iii. pp. 217-238 (1887), with later studies by Professor Hull. 
7 By Henry Benest, Geog. Fourz., London, vol. xiv. pp. 394-413 (1899). 
8 Geog. Fourn., London, Feb. 1905. 
22 
