CONFIGURATION OF THE 1SF.ANDS 261 



So far as the Caribbee ridge is concerned, the greatest land altitude is 

 5,000 feet and the greatest sea depth 17,064 feet. Hence the altitudes of 

 the highest Windward peaks above the deepest adjacent sea depression 

 are 22,064 feet. Thus about 29 per cent of the highest island masses 

 are exposed above sealevel and 71 per cent submerged. 



Surface configuration. — The above water physiography of the Windward 

 islands is of two distinct types : (1) Primarily volcanic piles with typical 

 slopes intensely etched by erosion, and (2) flat and terraced plains 

 veneered with oceanic lime material. Some islands are composed en- 

 tirely of one of these types and some of the other, while one or two are 

 a combination of both. The outer chain of islands is largely of the flat- 

 tened bench and plain type. 



All of the inner belt of the Caribbee islands are primarily construc- 

 tional volcanic piles. In most instances they present typical volcanic 

 slopes, and sometimes distinct crater-like forms are evident. The relief 

 of these piles also shows that there has been intermittent accretions — 

 intervals of piling-up, alternating with intervals of quiescence and erosion. 



There are other topographic features of the islands, modifications of 

 the old constructional forms, at times almost destruction, which are all 

 the result of the secondary processes of atmospheric and marine erosion. 



Stream valleys are always numerous on the volcanic piles; in many 

 cases they radiate out from the old summits. Except the delta plains 

 near their mouths, on which the coastal villages are usually built, these 

 exhibit no secondary topographic features, but are simple autogenous 

 streams. These stream valleys are often profound and numerous, and 

 sometimes ramify completely over the older piles. 



Important features of the islands are the sea cliffs and wave-planed 

 benches which surround them, the largest developed on the windward 

 side, truncating their borders and breaking the continuity of the profiles. 

 The benches are, of course, submerged and of shallow depth, and have 

 clearly been produced by the action of the surf. 



Still another topographic feature which can not escape the eye of even 

 the most amateur observer is the conspicuous levels here and there trace- 

 able on the profiles or extending in horizontal benches, much like those 

 now forming at the margin of the sea, some standing as high as 900 feet. 

 From some of these old benches, as at Nevis and Saint Kitts, rise the 

 more modern volcanic piles, while others apparently represent in the 

 history of the islands an erosion stage, followed by uplift, and still others 

 old wave-planed benches — volcanic piles which were first cut down, 

 veneered with oceanic debris, and then uplifted above the level of the 

 sea, so that they now present a surface of calcareous material. 



