8 TRANSACTIONS OF THE [oCT. 13, 



Surface Deposits. 



There is practically no soil either on New Providence or An- 

 dros, except the little that collects in the caves and holes in the 

 rock. From the caves a large quantity of cave earth has been 

 taken and sold as a fertilizer, with what result I do not know. I 

 was told that guano had been found on Andros, but I saw none. 

 The earths I collected I have treated with hydrochloric acid, and 

 the results indicate a great variation in composition. In some, 

 most of the material is soluble with strong effervescence, but in 

 others the residual, I suspect, will prove greater than the soluble 

 portion. The residue seems to be composed of organic material, 

 with some mineral constituents that contain an appreciable 

 quantity of iron. Dr. Waller, of the School of Mines, Columbia 

 College, has kindly offered to analyze my material, and we hope 

 from the results to draw some conclusions as to its origin. At 

 present it seems as if the earthy deposits are composed of the 

 insoluble portions of the coal rock mixed with vegetable par- 

 ticles. 



The absence of any large quantity of fallen leaves is very notice- 

 able. In the " Pine Yard," as the pine woods are locally called, 

 we did not see a single fallen pine, but the depressions in the 

 ground showed where one had formerly stood, and a long, shallow 

 trough plainly indicated where the fallen trunk had lain. Desic- 

 cation and decay take place with astonishing rapidity, and I be- 

 lieve that the deposits found in the caves are greatly added to 

 by the comminuted particles of dried vegetable matter, and the 

 residue of the decomj)osed portions, both of which would be 

 washed in by rain-water. 



On the ' ' swash " on the west coast of Andros a peculiar 

 ash-like deposit was noticed that covered small circular areas. 

 This on examination proved to be composed of soft, elastic lumps 

 coated with calcareous material. These lumps under the micro- 

 scope were seen to be composed of one of the small, probably 

 fresh-water, alga^ that had grown in the pools of water, and 

 which had been left when the pools had dried. 



Erosion, 



One of the most striking geological changes taking place in 

 the Bahamas is the erosion of both the surface and the shore 

 line of the islands. 



West of Xassau, on the beach, are many places where the waves 

 have cut narrow passages into the rocks and ground the frag- 

 ments into sand. There are also a number of "pot-holes": 

 these were circular in horizontal sections, and the bottom and 



