BIGELOW. — SHOAL-WATER DEPOSITS OF THE BERMUDA BANKS. 571 



of a small amount of broken shells and a larger amount of fine silt, most 

 of which is either white marl or of terrigenous origin. 



St. George's Harbor is an enclosed sound of much smaller area than 

 Castle Harbor, and is much more nearly landlocked, its only direct com- 

 munication with the sea being through three narrow channels on the 

 northeast, two of which are shallow. On its northwest border there is a 

 considerable bisiht. Mullet r»ay by name, with a shoal bar at its mouth; 

 and at the southern end Smith's Island cuts off Smith's Sound and Dolly's 

 Bay, which together form another practically enclosed bight. The 

 greatest depth of St. George's Harbor is seven fathoms, and the chief 

 tidal current is through St. George's Channel. The bottom samples at 

 seven fathoms consist of a rather coarse dark gray sand of very much 

 water-worn shell fragments, together with the plates and spines of Toxo- 

 pneustes, a few large Foraminifera, and the calcareous alga Halimeda. 

 There are very few living organisms of any kind, and there is a consider- 

 able proportion, about 30 per cent, of fine calcareous silt, which is of 

 limestone origin, but, unlike the "marl " already mentioned, of a bluish 

 gray color. On the north side of the Harbor, between Horseshoe and 

 St. George's islands, in two fathoms (Station 448), the bottom is fine 

 grayish blue sand, coherent, with 75 per cent fine ooze. Foraminifera, 

 especially Polystomella, form 10 per cent, and nullipore, gasteropod, 

 bivalve, millepore, and echinoid fragments, 10 per cent. The fine ooze 

 consists almost wholly of impalpable, flocculent, amorphous, calcareous 

 dust, stained gray ; probably in large part of terrigenous origin and very 

 similar to the bottom at Mullet Bay. Although this passage communi- 

 cates with the sea, it is closed by a very shoal bar ; it is a region of rapid 

 deposition and with few living organisms. 



The cut between Horseshoe and Paget islands (Station 447) is deeper. 

 A sample from three fathoms at the inner end of the cut is dark blue 

 sticky mud, slightly coherent ; 50 per cent fine ooze ; Foraminifera, — 

 especially Polystomella biloculina, Orbitolites, Hastigerina, and Tex- 

 tularia, — 15 per cent; the remainder being calcareous algae, millepores, 

 and mollusks in about equal abundance, with a few Serpulae and 

 Polyzoa. The fine ooze is of the same composition as in the last 

 sample and there are few living organisms except the Foraminifera. The 

 coarse portion of the sample is evidently water-worn reef detritus swept 

 in through the channel by the tides. 



In St. George's Channel, the chief passage between St. George's 

 Harbor and the outer lagoon, the bottom is bluish gray mud, of the 

 same composition as in the Harbor, the proportion of coarse sand 



