PART II. 



HYPOZOIC AND PALEOZOIC ROCKS. 



BY E. HITCHCOCK, SENIOE. 



These rocks, with one or two unimportant exceptions, occur only in that part of the State 

 west of the Green Mountains, so far as has yet been ascertained. We find there a succession 

 of formations, whose order of superposition is settled in other parts of the country, and in 

 some cases in Vermont ; but often in consequence of inversion, faults and metamorphism, 

 it is obscure and undetermined. These rocks are the oldest of the stratified class on the 

 globe. Of the hypozoic series, Vermont contains, so far as we yet know positively, only a 

 small belt, which is, however, the eastern edge of an immense development of the same in 

 New York. The oldest of the palsezoic series lies directly upon the hypozoic, at least in 

 one point ; and from thence, as we proceed towards the Green Mountains, we can trace 

 the usual order ; not, however, in many cases without supposing that the strata have not 

 only been folded together by some lateral force, but actually thrown over, so as to produce 

 inverted dips; and not only so, but that there have been extensive risings and sinkings of 

 strata along extended cracks or faults. Still, so long as the fossils are not obliterated, the 

 order of superposition can be traced out. But as we approach the Green Mountains, 

 metamorphism has so nearly destroyed the fossils, that the identification of the strata 

 becomes extremely problematical, until at length we lose the clue entirely, and can only 

 conjecture the age of the formations. Could we keep hold of it, Part II. would probably 

 embrace all the rocks of the State ; but since those in and east of the Green Mountains 

 must be distinguished mainly by their lithological characters, we group them into a third 

 class, and offer only conjectures as to their age. 



Before entering upon a detailed description of either of these classes, a few preliminary 

 remarks seem desirable, especially for such as may not be familiar with the phenomena of 

 plication, inverted dips and faults. 



The prevailing dip of the rocks of Vermont is easterly, or rather somewhat southeast- 

 erly. This is particulai'ly the case with the fossiliferous rocks. But an inspection of our 

 sections will show that the exceptions are very numerous in the other parts of the State. 

 A large number of anticlinals and synclinals exist, and of course frequent westerly dips. 

 The whole is reasonably explained by supposing the strata to have been crumpled up by 

 a force coming from the southeast; the effects modified, perhaps, in some cases by protru- 

 sions of granite ; and since the time of disturbance and plication, the tops of the folds 

 have been worn away, so as to leave only the outcropping edges of the strata in sight. 

 The various sections we shall give, afford illustrations of all these phenomena. But we 

 bring them together in the following sketch, which was not taken from nature ; yet there 

 is a general correspondence between this section and those we have given crossing the 

 State, say the one from Guildhall to Sister's Island, No. XI. 



