Fluvial Theory. 



519 



trusion of the unstratified. That is, the oldest stratified rocks exhibit 

 far more of disturbance than those of more modern date ; many of 

 which have not been disturbed at all. This cannot be explained by 

 supposing that the older rocks have been affected by all the paroxys- 

 mal efforts of volcanic power that have occurred, whereas the newer 

 ones have felt only the modern throes : for the latter products of vol- 

 canic action, such as basalt, greenstone, trachyte, and lava, appear 

 but in a few instances to have disturbed the older rocks. 



5. The vents of existing volcanoes are always situated in the midst 

 of regions exhibiting marks of former and extinct volcanic action ; 

 and they occupy but a small proportion of those regions ; indicating 

 a comparative repose or diminution of the volcanic power. 



6. In correspondence with the preceding facts, we find the older 

 rocks, both stratified and unstratified, more crystalline in their struc- 

 ture than the newer ones : an effect which would result from the di- 

 minished agency of heat. 



7. The character of organic remains implies a like diminution of 

 temperature : nor can the astronomical theory of Mr. Herschel, mak- 

 ing this diminution the result of a gradual change in the ellipticity 

 of the earth's orbit ; nor the geographical theory of Mr. Lyell, which 

 refers it to variations in the relative position of land and water, and 

 in the elevation and form of land : afford any satisfaction to the mind. 



8. The occasional occurence in the sedimentary rocks of immense 

 beds of conglomerate, indicates the occasional recurrence of power- 

 ful debacles of water to form and collect the materials for these rocks. 

 But we know of no cause now in operation adequate to the produc- 

 tion of such deluges. Yet if we admit the greater intensity of vol- 

 canic power in past times, an adequate cause is provided. 



9. Existing diluvium cannot be accounted for by causes now in ac- 

 tion. This point, in relation to the diluvium of Massachusetts, has 

 been so fully discussed in the earlier pages of this report, that I need 

 add nothing further in this place, except to say, that the diluvium of 

 other countries appears to be quite as difficult to be accounted for by 

 the fluvial theory. 



Upon the whole, it seems to me that however easily a man may 

 persuade himself in his cabinet, of the truth of the theory that has 

 been examined, he cannot go forth among the mountains without 

 meeting its refutation every where ; and he must be continually im- 

 pressed with the vast intensity of force which aqueous and igneous 

 agents have exerted on the globe in former times. 



