238 :mk. jitees-browne and prof. Harrison 



tests of various marine organisms, only the upper part being trulr 

 coral-rock *. 



Prof. Agassiz found raised reefs also on the southern coast, 

 especially on the hills surrounding Havana and extending to 

 Matanzas. " These hills," he says, " attain a height of over 

 1200 feet, and are entirely composed of species of corals identical 

 with those now found on the living reefs " (oj). cit. p. 71). 



I entirely agree with him in thinking that the raised reefs of 

 Cuba were formed during periods of rest, each of which was suc- 

 ceeded by a period of elevation : but I cannot agree with his view 

 that Florida was originally joined to the raised reefs " which formed 

 before the Tertiary the two extremities of Cuba" {op. cit. p. 75). 



§ 7. Physical Geographt oe the Caribbean Kegion during 

 THE Formation op the Eeees. 



From the foregoing descriptions of the raised coral-reefs of the 

 West Indies it is clear that many of the islands have been raised 

 through a considerable vertical height in a comparatively recent 

 period, and it also seems safe to infer that the elevation of these 

 islands has been due to a general regional uplift, and not to a series 

 of special and local upheavals. If the raised reefs only occurred on 

 small islands like Barbados and Antigua, which exhibit signs of 

 special local upheaval, we could not have been sure that there had 

 been any general regional elevation since Pliocene times, though it 

 would be difficult to account for the uplift of deep-seated oceanic 

 deposits without supposing a great and extensive elevation. But 

 as coral-rock is found at high elevations in Cuba, and probably also 

 in Jamaica, we are entitled to assume that the upheaval of the 

 other islands was part of a regional movement. The proved extent 

 of this movement in the eastern part of the region is 1300 feet, and 

 in Cuba about 1800 feet. 



The larger islands were in existence when the highest reefs began 

 to form around them, but the AYindward Islands must have been 

 few and small. We may assume that Barbados and the eastern 

 part of Guadalupe (Basse Terre) made their appearance about the 

 same time, and that the little islands of Barbuda and Anegada were 

 among the last to rise above the waves, their appearance in fact 

 being contemporaneous with the formation of those Barbadian 

 terraces which lie below the 100-feet contour. 



The distance between Barbados in the east and Havana in the 

 west of the region is about 1800 miles, and, as the height to which 

 the reefs have been lifted in Cuba is rather greater than that of the 

 highest reefs in the Windward Islands, we may assume that the 

 upheaved area extended still farther to the west. jS'ow, Havana is 

 only 300 miles, and the west cape of Cuba only 140 miles, from 

 Yucatan, which is known to be a raised plateau of recent marine 

 limestone, and was clearly, therefore, within the area of elevation, 



* See footnote, p. 110, in Bull. Harvard Mus. vol. xiv. (1888), "Three 

 Cruises of the ' Blake.' " 



