Wadsworth.] . 478 [March 17, 
that known eruptive rocks have, but they do exhibit those, as said 
before, that no stratified rock has, so far as our present knowl- 
edge, not theory, goes. | 
It is not to be overlooked that the bog theory of their origin de- 
mands the following hypothesis, if we adopt the prevailing views. 
The rocks on which this material was deposited, must have been at 
that time metamorphosed or indurated to some extent. Hence they 
must have been originally depressed under the slowly accumulating 
weight of sediments down to the zone of aqueo-igneous fusion or 
near it. They must then have been as slowly elevated, denudation 
removing the superincumbent material. When restored to their orig- 
inal level or near it, the limonite was slowly deposited on their up- 
turned and crumpled edges. ‘ Again the sediments accumulated and 
eradually these rocks with the limonite sank down to the zone of 
aqueo-igneous fusion or solution, the former passing through it. This 
selective zone picked out the limonite and siliceous mud associated 
with it, producing upon them all the marks of plastic eruptive mate- | 
rial, which was squeezed in and through the overlying and underlying 
rocks, the latter remaining unaffected. Denudation again resumed 
its sway, and slowly and silently these rocks, buried four, five, ten, 
twenty or thirty miles beneath the surface, again appeared. ‘These like- 
wise are denuded and have deposited over them a conglomerate com- 
posed of their metamorphosed debris. Again down they went to or 
near the same zone when another elevation took place, and the Pots- 
dam sandstone was deposited. We should then have three distinct 
ages in the “ Huronian,” all separated by vast intervals of time, in- 
stead of one period. Let us then imagine what this sedimentary 
theory demands in time and realize that this depression and eleva- 
tion takes place through the influence of slowly deposited sediment 
on an earth “ more rigid than glass and only less rigid than steel.” Im- 
agine the power required to elevate this vast area, the cubic miles of 
sediment to be deposited, and rock to be removed three times over. 
On the other side the eruptive origin requires simply that the 
schists and sandstones should be deposited as usual, and the jas- 
pilite and ore erupted as overflows and intrusive masses. No 
metamorphism is required or distinct age demanded, for as soon as 
cooled the rock would have nearly its present condition, and if 
poured out upon a sea shore would, as soon as solidified, be acted 
upon by the waves, forming the observed conglomerates. 
