Vol. 57.] PHYSICAL DEVELOPMENT OF ST. KITTS, ETC. 539 



VI. Date of the Volcanic Eruptions. 



We are now in a position to consider the volcanic accumula- 

 tions in relation to the marine deposits which overlie them. Some 

 of the volcanic sands underlie the marls which thinlj'' cover the 

 floor of the sunken coastal plains, as seen in the limestones of Brim- 

 stone Hill and The Quill ; consequently, the renewal of Tertiary- 

 igneous action commenced before the formation of the marls, 

 the sands beneath which contain the remains of recent shells. 

 There are no deep valleys dissecting the volcanic deposits of the 

 islands, such as appear indenting the submarine shelves, portions 

 of which, at least, are covered with these marls ; ' so that the 

 cinder-eruptions must have renewed the surfaces of the islands, 

 and largely built up the volcanic ridges since the marl-producing 

 epoch. Again, the mountain-ridges were completed nearly as we 

 now see them, before the elevation of the adventitious dome of 

 Brimstone Hill, which dates back only to the period of submergence 

 recorded in the gravel-formations of the mid-Pleistocene Period. 

 Consequently, the greatest volcanic activity appears to have been 

 during the earlier part of the Pleistocene Period, which was par- 

 ticularly characterized by stupendous changes of level of land 

 and sea, although these began somewhat earlier. Prom the fresh- 

 ness of the mountain-slopes, the eruptions seem to have recurred 

 nearly to the present day. This newness is impressed upon us, 

 when we see the destruction wrought by the rains, precipitated by 

 the mountains from the trade-winds. Clouds hang over, if they do 

 not envelop, Nevis and Mount Misery for most of the year. During 

 a storm lasting three hours, in 1880, there was a local condensation, 

 so that a rain-gauge of 30 inches at Basse Terre was filled and 

 overflowed (teste Dr. Branch). The terribly destructive effect of 

 such a rainfall is understood, even without adding that the slackened 

 currents deposited in the town from 4 to 6 feet of mud. Yet 

 outside of the influences of the mountains, the rainfall, even in this 

 tropical region, is very moderate, as in Antigua and Anguilla. 



While corals grow upon the coast and obstruct some of the 

 channels on this submarine shelf, they are not found in reefs 

 elevated above the sea. 



VII. Notes on Pcedonda and Montsereat. 



Sailing from Nevis to Montserrat, one passes the lonely rock of 

 Eedonda, rising to a height of 600 feet, which has so far defied 

 the stress of storms and waves. A phosphate-deposit has been 

 worked upon its surface, but I am unaware of its geological relation- 

 ship, not having landed on the island. 



Nor have I seen Montserrat, except from the deck of a steamer. 

 Yet it is made up of volcanic peaks similar to others of the chain, 

 the highest attaining an elevation of 3002 feet. Remnants of a 

 limestone occur at a headland, and specimens were shown to me by 



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