AGASSIZ: BAHAMAS. 37 



kind of sticky marl, — greatly decomposed aeolian sand. The nature 

 of the bottom is accurately noted on the charts, and from the examina- 

 tion of the many samples collected it will be quite possible to give an 

 excellent account of its characteristics. 



On our way south we attempted to reach some of the ocean-holes 

 marked as existing near Blossom Channel. Unfortunately the sea was 

 too rough, and it was impossible in the disturbed condition of the bottom 

 to recognize their position. 



Harvey Cay is connected with the outer cays to the south of it by a 

 number of small low cays, half eaten away by the action of the sea, which 

 reach to Exuma Sound. They form a series of narrow parallel lines 

 of rocks, with passages like those of Rudder Cut between some of the 

 cays. These islets are in every respect similar to the numerous small 

 islets we saw as we passed through Conch Cut (Plate XXXVI. ). They 

 extend across the passage between Harvey Cay and Great Guana Cay. 



From Harvey Cay to Great Ragged Island and Columbus 

 Bank. — The Sand Bores of the Bank. 



Plate I.; Plate XI. Figs. 3, 5; Plate XII. Figs. 1, 3, 4; Plate XXXV. 



The passage round Galliot Bank gave us an excellent idea of the alter- 

 nating channels which exist between the different sand ridges running in 

 a westerly direction from Galliot Island to the Barracouta Rocks. The 

 navigation is entirely by the eye, and the boat is forced across the deep- 

 est part of a terminal ridge or of a lateral spur into the nearest channel. 

 To the windward and leeward we could see on each side three or four 

 additional bores, parallel in a general way to the two between which 

 we were steaming. The channels and their probable depth were fairly 

 indicated by the color of the band of water separating them. This 

 bank is very similar to the bores to be seen on many other parts of the 

 bank. The sand bores and sand spits separating the channels are 

 plainly indicated by the light emerald-green color of the water, which 

 is in marked contrast to the darker purplish color of the belts of deeper 

 water forming the navigable channels. 



Of course, where there is such constant disturbance over the bottom, 

 and shifting of these large sand masses in accordance with the action of 

 the winds prevailing for any length of time, as on the Galliot Bank, we 

 were not surprised at finding the bottom bare of all animal or vegetable 

 life. 



