‘a1 a a a 
10 GEOLOGICAL SURVEY 
into the argillaceous rocks of older fossiliferous strata, in such a manner that nothing but the pre- 
sence of fossils in the latter will enable us to distinguish them. 
RELATION oF THE IGNEOUS AND Meramorpuic Rocks. 
Although granite is found, of various ages, protruded through, and even overlying some of the 
newer rocks, nevertheless it always constitutes the foundation of the oldest stratified rocks, which 
are often found resting against it in highly inclined positions. 
The inclination observed in stratified formations is a subject of great interest and practical im- 
portance. 
That all rocks deposited from water were originally horizontal, or nearly so, can admit of no 
reasonable doubt ; for it would be absolutely impossible for sedimentary matter to be deposited on a 
plane inclined beyond a certain angle: so that when we find strata standing nearly or quite ver- 
tical, we are forced to the conclusion that they were pushed up by some mechanical force, acting 
from below. We often find disturbances in the lower rocks, which did not extend to those above; 
and this we find through all the series, showing that from the very beginning such disturbances 
existed. These subterranean movements varied in intensity, from a force barely sufficient to pro- 
duce a gentle flexure in the strata, to one sufficiently powerful to elevate and rend asunder the 
crust of the earth throughout its entire thickness. 
The rents and dislocations seen in mountain regions show that violent and sudden changes have 
been effected ; and we have evidence equally conclusive that vast changes have taken place slowly 
and without leaving on the surface traces of disturbance. It is remarkable that these disturbing 
forces should have acted in lines of nearly uniform direction, as the courses of the great mountain 
chains fully attest. Although the action of these forces was more energetic at some periods than 
at others, yet we have abundant proof that they are stiii at work, in the numerous alterations of 
level of very modern date which every country presents. 
The annexed cut (Fig. 2) will illustrate the nature of the changes produced by these disturbing 
forces, as well as the connection of the igneous and metamorphic rocks. 
G—Granite. 1—Gneiss. 2—Micaslate. 3—Clay slate. 
The physical imposibility of the deposition of sedimentary matter at an angle so great as that 
presented by the inclined beds of stratified rocks, has already been alluded to; but besides this, the 
points of contact with the igneous rocks show very clearly that the latter have been forced up in 
