224 On Fossil Reptilian Remains in Nova Scotia. 



indefinite extent of past time, that there is, practically speak- 

 ing, a rooted and perhaps unconscious reluctance on the part 

 of most geologists to follow out to their legitimate conse- 

 quences the proofs, daily increasing in number, of this im- 

 mensity of time. It would therefore be of no small moment 

 could we obtain even an approach to some positive measure of 

 the number of centuries which any great operation of nature, 

 such as the accumulation of a delta or fluviatile deposit of great 

 magnitude may require, inasmuch as our conceptions of the 

 energy of aqueous or igneous causes, or of the powers of vita- 

 lity in any given geological period, must depend on the quan- 

 tity of time assigned for their development. 



Thus, for example, geologists will not deny that a vertical 

 subsidence of three miles took place gradually at the South 

 Joggins during the carboniferous epoch, the lowest beds of 

 the coal of Nova Scotia, like the middle and uppermost, con- 

 sisting of shallow-water beds. If, then, this depression was 

 brought about in the course of 375,000 years, it did not exceed 

 the rate of four feet in a century, resembling that now ex- 

 perienced in certain countries where, whether the movement 

 be upward or downward, it is quite insensible to the inhabi- 

 tants, and only known by scientific inquiry. If, on the other 

 hand, it was brought about in two millions of years according 

 to the other standard before alluded to, the rate would be only 

 six inches in a century. But the same movement taking place 

 in an upward direction would be sufficient to uplift a portion 

 of the earth's crust to the height of Mont Blanc, or to a ver- 

 tical elevation of three miles above the level of the sea. In 

 like manner, if a large shoal be rising, or attempting to rise, in 

 mid-ocean at the rate of six inches or even four feet in a hun- 

 dred years, the waves may grind down to mud and sand and 

 readily sweep away the rocks so upraised as fast as they come 

 within the denuding action of the waves. A mass having a 

 vertical thickness of three miles might thus be stripped off in 

 the course of ages, and inferior rocks laid bare. So in regard 

 to volcanic agency a certain quantity of lava is poured out 

 annually upon the surface, or is injected into the earth's crust 

 below the surface, and great metamorphic changes resulting 



