576 



IMBEDDING OF AQUATIC SPECIES 



[Ch. XLVIII. 



comparatively shallow parts of tlie neighbouring straits, 

 through which a powerful current flows. Beds of shelly sand 

 might here, in the course of ages, be accumulated several 

 thousand feet thick. But without the aid of the drifting power 

 of a current, shells may accumulate in the spot where they 

 live and die, at great depths from the surface, if sediment be 

 thrown down upon them ; for even in our own colder latitudes 

 the depths at which living marine animals abound is very 

 considerable. Captain Yidal ascertained, by soundings made 

 oif Tory Island, on the north coast of Ireland, that Crustacea, 

 Starfish, and Testacea occurred at various depths between 

 50 and 100 fathoms ; and he drew up Dentalia from the 

 mud of Galway Bay, in 230 and 240 fathoms water. 



The same hydrographer discovered on the Eockhall Bank 

 large quantities of shells at depths varying from 45 to 190 

 fathoms. These shells were evidently recent, as they re- 

 tained their colours. In the same region a bed of fish-bones 

 was observed extending for two miles along the bottom of 

 the sea in 10 and 90 fathoms water. At the eastern ex- 

 tremity also of Kockhall Bank fish-bones were met with, 



^led with pieces of fresh shell, at the depth of 235 



mm 



fathoms. 



Analogous formations are in progress in the submar 



tracts 



from 



Shetland Isles to the north of 



Ireland, wherever soundings can be procured. A continuous 



deposit of sand 



mud 



with broken and entire 



shells. Echini, &c., has been traced for upwards of twenty 

 miles to the eastward of the Faroe Islands, usually at the 

 depth of from 40 to 100 fathoms. In one part of this 

 tract (lat. 61° 50^, long. 6° 30^) fish-bones occur in extra- 

 ordinary profusion, so that the lead cannot be drawn up 

 without some vertebrse being attached. This ' bone bed,^ as 

 it was called by our surveyors, is three miles and a half in 



fathoms 



interming 



In the British seas, the shells and other organic remains 



mud 



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