REVIEMS 115 



in Guadeloupe proper and Dominica, they are covered with volcanic 

 materials which constitute more or less of the cones and ridgfes, rising 

 to a height of 3,000 to 4,000 feet. In these mountainous islands there 

 is not merely a combination of late and ancient eruptive deposits, but 

 there are several formations secondarily derived from the remains of 

 the older basement, and here is room for more study than has been 

 attempted. 



The history of one is more or less the history of all of these coni- 

 cal islands. For instance, in Dominica there is the old andesitic 

 rock, overlaid by volcanic breccia or conglomerate. At other points 

 the age of the tuffs cannot at present be assigned, but some of them 

 have been denuded into relatively large valleys, which have been partly 

 refilled with still newer tuff (like that of the Roseau valley), containing 

 an abundance of water-worn pebbles, often arranged in lines among 

 the more angular material. Such may correspond to the early Tertiary 

 subaqueous tufaceous beds of Grand Terre (Guadeloupe). And these 

 beds have been subsequently tilted outward at considerable angles. 

 As in St. Martin and Antigua and Grand Terre, there is nothing to 

 show that there were any mid-Tertiary eruptions when the whole region 

 was somewhat elevated and the denuding agents were molding the sur- 

 face into rounded outlines. From the corresponding topography 

 in the more volcanic islands, where not surmounted by the modern 

 cones, the impression is left that the volcanic activity of the region was 

 quiescent during much of the Miocene-Pliocene period, before the 

 building up of the cones and ridges, which were constructed at a rela- 

 tively late date, for we find the sea bed elevated along with these 

 ridges. Thus we find in Statia and in St. Kitts volcanic cones raised 

 by an upward thrust which carried along with it the sea-floor, covered 

 by about thirty feet of marl now forming broken mantles surrounding 

 the cones to elevations of from 400 to 900 feet. Elsewhere, however, 

 we find fragments of a similar formation appearing with the volcanic 

 Tocks brought up by a general elevation of the island. These lime- 

 ■stone marls contain practically a living fauna, thus showing the eleva- 

 tion to date no farther back than the end of the Pliocene period. 

 Again, there are two series of gravel formations, one of which is older 

 than the coralline strata just mentioned as interbedded with the vol- 

 canic ejectamenta ; but this gravel formation had its surface greatly 

 denuded before the formation of the marl. Again, both the marl and 

 the gravel have been further subjected to erosion so as to be often left 

 only in broken series. The newer gravel has not been subjected to so 



