176 DREDGINGS OF THE MARINE BIOLOGICAL ASSOCIATION: 



Even now, could the fine sands which float about in the Channel 

 find a resting-place in its main water-way, a very short period would 

 suffice to bury the stones and boulders. The surface tow-nets used on 

 the cruises undertaken for the purposes of the International Sea 

 Fisheries Investigations constantly catch considerable quantities of 

 fine sand. But sand which by wave disturbance can be maintained at 

 the surface over a depth of forty or fifty fathoms requires but a slight 

 current to prevent it coming to rest on the bottom. It is not 

 necessarily that the currents scour the inorganic sand from the sea- 

 bed, but that they prevent its settlement there. 



As regarding organic carbonate of lime, shell, and other material, 

 which is forming even now in the deeper parts of the Channel, the 

 currents must be credited with removing some of this mechanically, 

 some by solution, as the particles become finer by disintegration, and 

 the redeposit of such material must take place in quieter waters. 

 Otherwise from the accumulation of this debris alone the stones would 

 long since have been entirely covered. 



Defective argument may be based on accurate observation, and if 

 the hypotheses above put forward are found incapable of bearing the 

 test of closer reasoning or of fresh discovery, the apology for their 

 being must stand — that they are based in fact, and in fact the state- 

 ment of which has been in no way influenced by them. 



On two points further work is in hand : the examination of the 

 flints for fossils, and the closer inspection of the baked shales from the 

 neighbourhood of the presumedly Post-Carboniferous Granite. 



AN ADDITIONAL NOTE.— THE SANDS AND GRAVELS. 



Fine materials, sands and gravel, from eighteen dredgings have 

 been examined, but not in such detail as might be desirable. 



As a whole the mineralogical results confirm the conclusions derived 

 from the stone samples ; so closely are these in agreement that a very 

 few points need be noted. 



M. 29. S. 14° W. Edd., 19 S miles, gives exactly the same results in the 

 fine material as in the pebbles, small fragments of the passage-bed 

 marls being fairly frequent, and no Triassic rocks present. 



M. 71. S. 23 W. Edd., 190 miles, yields Triassic material, which M. 72, 

 a coarse dredging from the same spot, did not ; this is within the New 

 Eed Sandstone area. 



M. 75. S. 20' W. Edd., 381 miles, yields a little Trias. 



M. 65. S. 22° W. Edd., 422 miles, possibly contains a little Triassic 

 material. 



