IMPERFECTION OF GEOLOGICAL RECORD 69 



can this have happened during the alternate periods of 

 elevation; or, to speak more accurately, the beds which 

 were then accumulated will generally have been de- 

 stroyed by being upraised and brought within the limits 

 of the coast-action. 



These remarks apply chiefly to littoral and sublittoral de- 

 posits. In the case of an extensive and shallow sea, such 

 as that within a large part of the Malay Archij^elago, where 

 the depth varies from 80 or 40 to 60 fathoms, a widely 

 extended formation might be formed during a period of 

 elevation, and yet not suffer excessively from denudation 

 during its slow upheaval; but the thickness of the for- 

 mation could not be great, for owing to the elevatory 

 movement it would be less than the dejDth in which it 

 was formed; nor would the deposit be much consoli- 

 dated, nor be capped by overlying formations, so that 

 it would run a good chance of being worn away by 

 atmospheric degradation and by the action of the sea 

 during subsequent oscillations of level. It has, how- 

 ever, been suggested by Mr. Hopkins, that if one part 

 of the area, after rising and before being denuded, sub- 

 sided, the deposit formed during the rising movement, 

 though not thick, might afterward become protected b}^ 

 fresh accumulations, and thus be preserved for a long 

 period. 



Mr. Hopkins also expresses his belief that sedimentary 

 beds of considerable horizontal extent have rarely been 

 completely destroyed. But all geologists, excepting the 

 few who believe that our present metamorphic schists 

 and plutonic rocks once formed the primordial nucleus 

 of the globe, will admit that these latter rocks have 

 been stripped of their covering to an enormous extent. 



