THE IMPERFECTION OF THE GEOLOGICAL RECORD 279 



been destroyed by being upraised and brought within the limits 

 of the coast-action. 



These remarks apply chiefly to littoral and sub-littoral deposits. 

 In the case of an extensive and shallow sea, such as that within 

 a large part of the Malay Archipelago, where the depth varies 

 from thirty or forty to sixty fathoms, a widely extended forma- 

 tion might be formed during a period of elevation, and yet not 

 suffer excessively from denudation during its slow upheaval; but 

 the thickness of the formation could not be great, for owing to 

 the elevatory movement it would be less than the depth in which 

 it was formed; nor would the deposit 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 action 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 rising movement, though not thick, 

 might afterward become protected by 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. 

 For it is scarcely possible that such rocks could have been solidi- 

 fied and crystallized while uncovered; but if the metamorphic 

 action occurred at profound depths of the ocean, the former pro- 

 tecting mantle of rock may not have been very thick. Admitting 

 then that gneiss, mica-schist, granite, diorite, etc., were once 

 necessarily covered up, how can we account for the naked and 

 extensive areas of such rocks in any parts of the world, except 

 on the belief that they have subsequently been completely de- 

 nuded of all overlying strata? That such extensive areas do exist 

 cannot be doubted: the granitic region of Parime is described by 

 Humboldt as being at least nineteen times as large as Switzer- 

 land. South of the Amazon, Boue colors an area composed of 

 rocks of this nature as equal to that of Spain, France, Italy, part 

 of Germany, and the British Islands, all conjoined. This region 

 has not been carefully explored, but from the concurrent testi- 

 mony of travelers, the granitic area is very large: thus Von Esch- 

 wege gives a detailed section of these rocks, stretching from Rio 

 de Janeiro for 260 geographical miles inland in a straight line; 



