NOTES ON THE GEOLOGY OF THE BAHAMAS 43 



grow smaller and smaller, and the forest is often prolonged into points 

 that run out in the swash and are composed of young and vigorous 

 trees. There are also in the swash small and slightly elevated pieces 

 of land barely above the level of the surrounding ground, and on these 

 are growing young pines. These facts show that the pines are advanc- 

 ing as fast as the conditions admit. Now, we may fairly suppose that 

 within very recent geological times the atmospheric conditions were 

 practically the same as now, and that the outward growth of the pines 

 is limited by the elevation of the land from the influence of the salt 

 water. Now, had the land once been as high as at present, it is fair to 

 suppose that the pines would have taken possession of the places they 

 now occupy; and if subsidence was in progress, they would now be 

 being driven back from their vantage ground. i\nd we may also sup- 

 pose that before the change from elevation to subsidence had taken 

 place, time enough to allow the pines to grow old would have elapsed; 

 and hence were the island now sinking, or rather had it recently been 

 sinking, we should expect to find on the western shore the pine forest 

 with an array of old and dying trees facing the sea, and it would not 

 be surprising if some dead pines were found standing in the water. 

 None of these appearances are to be found. 



The mangroves, too, point to elevation, for I find recorded in my 

 note-books instances of mangroves, far above high-water mark, that 

 were apparently dying, but none were seen in situations that indicated 

 that the water was becoming too deep for them, as would probably be 

 the case if the land had been recently sinking. 



These facts have perhaps been treated with too much detail; but 

 when I had been only to Nassau, and had seen the active erosion that 

 was taking place, I was inclined to think that the islands were sinking, 

 and was afterwards forced by the facts given above to alter my conclu- 

 sion. That most of the cays are being worn away and reduced in size 

 is evident. The vegetation is being driven backward, as indicated by 

 the old and gnarled appearance of the bushes and by the rhizomorphs 

 that remain where the plants once grew. But on the west side of Andros 

 the water is so shallow for a long distance seaward that there is practi- 

 cally no erosion of the land by the waves. A little bank of coral sand 

 and foraminifera raised slightly above the level of the swash is the only 

 evidence of the action of the water. 



