AGASSIZ : BAHAMAS. 



23 



would readily account for the deep ocean-holes, one of which has been 

 sounded to a depth of thirty-eight fathoms. These caverns would, if the 

 islands sauli to their full height, appear like ocean-holes in the general 

 levels of the bank. 



Moss Hill Blutf shows also the manner in which huge isolated rocks, 

 sometimes twenty to thirty feet in height, like Cow and Bull on Eleu- 

 thera, near the Glass Window, may be left as fragments of hills formerly 

 much higher, but gradually eaten away on the sides where parts of the 

 rocks are not protected on the surface by a coating somewhat harder 

 tlian tliat of the surface rock immediately surrounding them. 



Tliere are two bluifs to the north of Moss Hill, which now stand 

 out like rounded knobs above tlie sun-ounding country, and which in 

 time may appear almost like erratic boulders left high and dry, or like 

 huge masses thrown up perhaps during a great hurricane. 



The seolian rock sand from the bottom where we anchored is coarse 

 and of a grayish color. 



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SECTION ACROSS NEW PROVIDENCE. 



A section of the island of jSTev/ Providence in a nearly north and south 

 line from Nassau to the south shore is most instructive. 



Leaving the shore at Nassau, we follow up Nassau Street, and at the 

 quarries cross the crest of the ridge. The slope falls rapidly to the level 

 of the extensive plain of Grantstown, which separates the shore range 

 from tlie Blue Hills range. On the flat the exposed seolian rocks are 

 greatly honeycombed and weather-worn, the whole surface occupied by 

 pits, banana-holes, pot-holes, and cavities of all sizes, which have formed 

 in the more or less rotten rocks of tlie Grantstown flat-. On both sides of 

 the road there are marshes and pools filling the depressions. It would 

 require but slightly deeper depression to change the greater part of the 

 mangrove marshes of this flat into lakes like Killarney, Cunningham, 

 and other ponds which lie in deeper sinks. The greater part of the 

 Grantstown flat is covered by low bushes (Plate XA'L), with here and 

 there patches of mangroves. 



At the foot of tlie Blue Hills we come upon the more or less amygdu- 



