AGASSIZ : BAHAMAS. 63 



Cays. The cays in this vicinity are more exposed to the action of the 

 sea, the eastern shelf of the bank being quite narrow, and in many cases 

 the eastern faces are formed by low vertical cliffs of aeolian rocks, thirty 

 to forty feet high, separated by short stretches of sand beaches. The 



DEVIL S BLUFF. 



north end of Bond's Cay and the sea face of Alder Cay are both very 

 much eaten by caverns, with rows and patches of loose angular blocks 

 thrown up above high-water mark. There is but little vegetation on 

 either Cay. Beaches and low cliffs alternate along the southern end of 

 Bond's Cay. Along the whole length of the north end of Whale Cay 

 the action of the sea is well marked in the undermining of the low 

 cliffs forming the sea face of the cay. 



The effect of the shallow wide shore shelf to the east of the Berry 

 Islands is very marked on the swell, which is far less powerful than on 

 the Atlantic or Gulf face of the bank, wherever deep water comes close 

 to the sea face of the cays. 



An extensive tract of sand bores, dry at low water, runs from the 

 Northwest Channel to Great Harbor Cay. In the whole of the track to 

 the eastward of them as far as the Berry Islands there is only a very 

 limited area with a depth of one fathom. To the westward of the cays 

 from Great Harbor Cay to Whale Cay the shores run into broad sand 

 flats. The westward extension of these sand flats forms the southern 

 edge of the bank from Whale Cay and the Chub Cays to the entrance 

 of the Northwest Channel and to the Joulter Cays. From that edge of 

 the bank extensive sand bores run diagonally across in the direction of 

 Haines Cay. (Hydrographic Chart, No. 26 a .) 



Fine patches and bars of corals follow us south, with lanes of sand 

 separating them and extending to the edge of the bank from three or 

 four fathoms into fifteen or sixteen. Toward the outer edge the corals 

 grow most vigorously. The same kind of bottom followed us as far as 

 Whale Cay. Corals begin to grow in from three to four fathoms, where 

 they are less disturbed by the constant movement of the coarse coral 

 sand of the bank, and hence the corals have not assisted in building 

 up the shores. Very few coral patches come close to the surface, as 

 they do in the Florida Cays, where the corals play an important part in 

 the formation of the outer ones. 



