149 
the folded veins of quartz in mica-slate, as no other hypothe- 
sis has done. It is consistent with the now accepted view of 
metamorphism by pressure, under the conditions of a moist, 
low heat. At all events, its ample discussion and copious 
illustration by Dr. Hitchcock and his son, in the pages of 
his report of the Geology of the State of Vermont, will re- 
main a part of the classics of our science. 
But the daring novelty of this excursion from the beaten 
track is heightened, when we see it as the short cut of an 
- old man to regain the head of the procession. So far from 
leading him into isolation from his fellows, his path lay prac- 
tically parallel with that of the best thinkers of the day. 
Most men of sixty-seven would tremble to adopt a new 
hypothesis. How few even at forty-five are able to be toler- 
ant of newer principles! But Hitchcock could follow where- 
ever Bischoff, Senarmont, Delesse, Daubrée, Sorby, and 
Sterry Hunt could climb. He could give up the igneous 
origin of granite, the extrusion of molten masses from a 
planetary nucleus of lava, the metamorphism of rocks by a 
high heat. He was no chamber geologist, and so kept his 
soul fresh in the open air that no new discovery could take 
him by surprise. “The opinion is now gaining ground,” he 
writes, “that in many cases, perhaps in nearly all, they are 
merely stratified rocks, which by heat, or the joint action of 
have lost their stratification and assumed 
They are, in fact, an extreme pro- 
He no longer believed in those 
ch no man has seen or can 
heat and water, 
new crystalline forms. 
duct of metamorphism.” 
semi-theological central fires whi 
see; in those figments of the imagination, a thin floating 
pellicle or wrinkling epidermis to the earth ; auniversal gran- ~ 
ite floor, beneath the lowest sediments, azoic and aboriginal ; 
a billowy deep of lava, g ing earthquake cataclysms, and 
ejections of interminable branching dikes of trap and por- 
13 
