Submarine Valleys and Cafions off American Coast 
In parts of the West Indian plateaus the surface rocks consist of coralline limestones of Pleistocene 
age. Beneath these, the newest formations are the white limestones of Oligocene or older Miocene age. 
They reach a thickness of 2000 to 3000 feet in Jamaica, At Matanzas, in Cuba, I found 1600 feet of 
the same (above a fault-line). Opposite this point, at Key West, Florida, borings in the same formation 
show a thickness of 2000 feet or more. 
These limestones are widespread over the West Indian region, showing that it was mostly under 
water in Mid-Tertiary days. There are also older crystalline schists. The modern volcanoes are confined 
to the minor portions of the chain of the small Windward Islands ; but some of these also date back into 
the Tertiary period or before. 
Date of the Great Cation-making Period—As shown by the character of the rock formations, the 
modern physiographic development of the West Indian region dates back only to the later Tertiary days. 
Even this being the case, I find, from the great amount of work performed on the land and sub-oceanic 
features, that the period of erosion was of long duration. The upper portions of the now submerged 
plateau became separated tablelands, which upon later subsidence formed the larger islands. It was then 
that the broad, rolling, open valleys were produced, reaching down to the then level of no erosion. This 
elevation of the region during the Mid-Pliocene period was moderate, yet 2000 feet of white limestones 
have been carried away from many places. Later followed another epoch of elevation of much shorter 
duration, so that the secondary valleys were excavated in the older broader ones. Then followed a 
subsidence somewhat below the present level, after which there was the great elevation with the formation 
of narrow deep cafions. From all of the evidence, on any theory whatsoever, the date of the great cafion- 
making period is found to have been at the close of the Tertiary or the beginning of the Pleistocene 
period. : 
Biological Evidence of the Connection of the Islands and Continent.—Three living (and one fossil) species 
of the rodent Capromys occur in Cuba and the same number in Haiti. These are related to Brazilian 
remains found in Pleistocene caves. Another species lives in Jamaica. One species of the insectivore 
Solenodon lives in Cuba and another in Haiti. This is related to a Madagascar type. Among the fossils 
found in caverns is the Oryctotherius (Myomorphus) cubensis (Pomel). This sloth is related to Megalonyx 
of North America. From Anguilla (one of the small north-eastern Antilles), Professor Cope described two 
species of Amblyrhiza (rodents as large as deer), related to Patagonian Pleistocene forms. These notes 
were given me by the late Professor E. D. Cope. I have found the Amblyrhiza in a cavern on the neigh- 
bouring island of St. Martin. Until recently, but little more was known of mammals of the West Indies. 
Although this collection seems meagre, it is sufficient to establish the former land connection 
between the West Indies and the continent. A writer on invertebrate fossils, Dr. T. W. Vaughan, 
published a paper attempting to show that fossil mammals did not exist in these islands, even the earlier- 
discovered great sloth, On the other hand, Professor Cope thought that many mammals had roamed 
over these lands, with their remains now occurring in the submerged lands. Confirmatory of their 
former existence in Cuba are the recent remarkable discoveries of Professor De le Torre, who has obtained 
additional specimens of the Myomorphus, and about eight species of mammals, besides other groups, from 
the Pleistocene caves of Central Cuba. 
At the time of his death, Professor Cope was investigating a large collection of remains of 
Pleistocene mammals from a cave at Port Kennedy, near Philadelphia. Among them were those of 
numerous bears of South American type, which had no corresponding relatives in the Western United 
States or in Mexico. This fact, and the physiographic evidence obtained by myself, led Professor Cope 
to the hypothesis that the migrations from South America had been by way of the West Indian bridge. 
Numerous species of plants occurring on the island of St. Croix, on the south-eastern side of the 
deep Anegada trench, are found on St. Thomas and in Puerto Rico, on the north-western side, but many 
of these may not afford evidence of land connection. 
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