Chap. X.] PAL^ONTOLOGICAL COLLECTIONS. 63 



and preserve the remains before they had time to de- 

 cay. On the other hand, as long as the bed of the sea 

 remains stationary, thick deposits cannot have been ac- 

 cumulated in the "shallow parts, which are the most 

 favourable to life. Still less can this have happened 

 during the alternate periods of elevation; or, to speak 

 more accurately, • the beds which were then accumu- 

 lated will generally have been destroyed by being 

 upraised and brought within the limits of the coast- 

 action. 



These remarks apply chiefly to littoral and sub-lit- 

 toral deposits. In the case of an extensive and shallow 

 6oa, such as that within a large part of the Malay Archi- 

 pelago, where the depth varies from 30 or 40 to 60 

 fathoms, a widely extended formation might be formed 

 during a period of elevation, and yet not suffer exces- 

 liively from denudation during its slow upheaval; but 

 the thickness of the formation could not be great, for 

 fiwing to the elevatory movement it would be less than 

 the depth in which it was formed; nor would the de- 

 posit be much consolidated, nor be capped by overlying 

 formations, so that it would run a good chance of being 

 worn away by atmospheric degradation and by the ac- 

 tion of the sea during subsequent oscillations of level. 

 It has, however, been suggested by Mr. Hopkins, that 

 if one part of the area, after rising and before being 

 denuded, subsided, the deposit formed during the ris- 

 ing movement, though not thick, might afterwards be- 

 come protected by fresh accumulations, and thus be 

 preserved for a long period. 



Mr. Hopkins also expresses his belief that sedimen- 

 tary beds of considerable horizontal extent have rarely 

 ^•)een completely destroyed. But all geologists^ except- 



