228 WALKS AND TALKS. 



mineral constituents of granitoid rocks had indeed been 

 formed as already stated quartz, feldspar, mica hornblende, 

 augite and they probably overspread these upheavals but I 

 believe these minerals must have existed under different as- 

 pects, and I think the minerals which compose the granitoid 

 rocks have resulted from metamorphism of plain sediments, 

 as I shall explain. We can not, therefore, look upon our oldest 

 "granite domes" as examples of the earliest crust, nor of the 

 earliest precipitated beds. They are later. Let us see. 



There were long, low ridges of barren rock now emergent. 

 I can not state where they lay ; but it seems probable they oc- 

 cupied nearly the places of later ridges which were to rise as 

 the germs of the continents. Old ocean now seemed envious 

 of his loss, for he immediately began pounding and devouring 

 the slender land, and taking it back into his possession. The 

 work of erosion was inaugurated, from which old ocean has never 

 desisted to this day. Nothing escaped from his domain with- 

 out a conflict ; and many a patch of land and many a conti- 

 nent has thus been reclaimed for his possession, as we 

 shall see. 



I wish to emphasize here a doctrine which has been very 

 generally overlooked. Ocean sedimentation has been carried 

 on only around the continental slopes. The products of ero- 

 sion have been laid down in waters comparatively shallow, 

 and not in the distant abysses of the ocean. The deep remote 

 sea-bottom remains to our times, with only a shallow covering 

 over the primitive crust. In our walk under the sea, we 

 found no continental sediments in the deep sea. We found 

 there a state of changelessness and stagnation. We found no 

 evidence of fragmental rocks. We found, on the contrary, 

 in the abyssal islands, rocks of igneous origin samples of the 

 old fire-formed crust, as I suspect. 



The accumulation of sediments over any portion of the 

 ocean's bed would constitute a thickening of the crust. But 

 the thickness of the crust was already adjusted to the intensity 

 of the heat within. It was of such thickness that the heat 

 within could not escape with rapidity sufficient to melt the 



