IGNEOUS AGENCIES. 



169 



This is of course only an approximate estimate, but we 

 may say with confidence that for thousands of years the 

 whole of Scandinavia, and perhaps much more, has been 

 rising bodily out of the ocean. 



Subsidence. 1. Greenland. The coast of Greenland, 

 for six hundred miles, is now subsiding, but at what rate 

 is not known. The subsidence is proved by the fact that 

 the houses built by the early Norwegian discoverers are 

 now partially submerged. The fact is so well recognized 

 by the Eskimos that they never build near the sea-level. 



2. River Deltas. In all great river deltas and perhaps 

 we might say in all places where abundant sediments are 

 accumulating, the earth-crust subsides as if weighted 

 down with the ever-increasing load. In digging or boring 

 into the delta of the Mississippi, the Ganges, or the Po, 

 the deposit is found to consist of an alternation of river 

 sediments with old forest-grounds, and sometimes peat 

 several feet thick, and occasional layers of limestone. 

 This is represented in Fig. 88, in which s s is the surface, 



FIG. 88. Section of river delta, ss, surface ; /, river-silt ; fg, forest-ground ; 

 I, limestone. 



with growing vegetation and accumulated vegetable mold, 

 and perhaps peat. As we go down we pass through river- 

 silt, r s, then an old submerged forest-ground, f g, with 

 black mold and stumps in place, as they grew, sometimes 



