160 DKEDGINGS OF THE MARINE BIOLOGICAL ASSOCIATION: 



currents the bed of any sea will become covered with deposits, the 

 average grade of which at any place will bear a relation to the depth 

 and the distance from land. And the strength of the sea currents 

 will in most instances accentuate this differentiation, being greatest in 

 shallower water. 



If, then, a contrary condition is found to exist, and the sands are 

 replaced, even in parts, in the deeper water by coarse beds and blocks 

 of stone, it becomes apparent that these latter belong in their origin 

 to other conditions than those now prevalent. The present rivers, the 

 cliffs which we see to-day have not supplied their material. Further, 

 we may surmise that a sea which exhiliits this anomalous feature, that 

 the materials of its bed grow larger in individual constituent parts 

 with distance from shore, cannot be, in its present form and depth, of 

 very ancient origin. The time available has not sufficed to enable 

 the shore-derived material to spread over the whole area. 



Austen has discussed these points very fully and with great clear- 

 ness ; in fairness to his work and in recognition of his precedence the 

 matter may be stated in his own words ^ : — 



" The law of progressive change in the character of the sea-bed 

 requires that the most remote deposits of the Channel should be the 

 finest, and that no coarse materials should occur at any considerable 

 distance from the coast ; this law holds good for a given extent round 

 all the shores of the Channel, but beyond the area of mud and ooze, 

 line and coarse sands, shingle and bare rock are again met with. . . ." 

 And referring to the coarse deposits on the Sole Banks and Jones Bank, 

 " the whole of these groups [of coarse material] are separated from 

 the zones of coarse materials depending on the coast-line by a broad 

 intervening area of the finest quality of seajbed. We are precluded 

 from supposing that the lines of coarse materials can have travelled 

 over the mud zones, as their upper surface is soft and incoherent, into 

 which the sounding-lead sinks some distance before the mass is 

 tenacious enough to stop it, and in which the dredge buries ; if there- 

 fore marginal or sub-marginal zone materials are found in places 

 beyond well-defined areas of the low moving power of water, they 

 become a clear indication that since their accumulation a great change 

 in the position of such place, as to depth of water and distance from 

 coast-line, has taken place." ..." It may be objected to this, that 

 these distant sand, gravel, and shingle beds may belong to any age, 

 and not in any way be connected with the present seas. In tracing 

 the remains of marine animals seawards, we may observe a like 

 gradual comminution with that noticed with respect to mineral 

 1 " Valley of the English Channel," Q.J.G.S., Vol. VI, 1850, p. 83 et seq. 



