T. S. Hunt on some points in Dynamical Geology. 265 
of the Paleontology of New York. A summing up of these 
views as put forth by me in the Canadian Journal in 
March, 1858, and in the Quarterly Geological Journal for 
November, 1859, will be found in this Journal for May, 
1861 * (II, xxxi, 411). In this last it was shown, in op- 
thus causing contraction of the mass. urther and very im- 
portant result of this accumulation there pointed out was by the 
softening of the underlying floor, or the “bottom strata to estab- 
ash lines of weakness or of least resistance in the earth's crust, and 
thus determine the contraction which results from the cooling of the 
Hence, I added, “ we conceive the subsidence invoked by Mr. 
all, though not the sole nor even the principal cause of the 
rocks, and their ejection as lavas, with attendant gases and 
vapors.” [Quart. Geol. Jour., Nov., 1859 
of the underlying strata upon which they were } sub- 
sidence probably spittin deine this process. Finally, this 
sytening determines a line of yielding to horizontal pressure, and 
& consequent upswelling of the line into a chain. Thus are 
accounted for first, the ilosidines; then the subsequent upheaval, 
and also the metamorphism of the lower strata.” Beneath every 
great line of sediments there will moreover be found, according 
him, a reservoir of sedimentary material in a state of more or 
* See also, On the probable seat of Volcanic Action, this Journal, If, 1, 21, and 
Geol. Mag., June, 1869. 
