254 J. B. WOOD WORTH APPALACHIANS IX NEW ENGLAND 



of doing so in the region of schists oecupving the middle area t>etween 

 Worcester and the Connecticut bouudarv. Here the question of the geo- 

 logical age of the schists regarded by Emerson as mainly Carboniferous 

 still provokes an inclination on the part of other geologists to regard the 

 low-lying dip of the schistosity as an indication of a Precambrian age. 



What follows in the statements of the present writer must therefore be 

 understood as made with full understanding of current opiuion regarding 

 the age of the rocks in that part of the State. From the point of view of 

 this pai>er, the acc-eptance of either view affects chiefly the question of 

 the amount of erosion and uplift of the rocks in the Worcester area dur- 

 ing and since the mountain-building of Paleozoic time. If, as Emerson 

 contends, the schists are Carboniferous, the vertical uplift relative to 

 sections on the west and east has been less probably by a few thousand 

 feet than would be the case if the rocks now at the surface are of Pre- 

 cambrian age. Xot being prepared to conhrm or deny the Carboniferous 

 age of the schists in question, the writer can only consider the conse- 

 quences of both structural views on the problem here dealt with. 



Western, central, and eastern Sections 

 the westerx sectiox 



On the west, the section ends rather abruptly against the little or not 

 at all folded Paleozoic rocks of eastern Xew York immediately west of 

 the Hudson River. On the ea^t, the folded and faidted structures of 

 ^lassachusetts imdoubtedly continue eastward beneath the sea-floor, with- 

 out an assignable Limit in that direction. In the middle part of Massa- 

 chusetts lies a belt of gently inclined crystalline schists, sharply folded at 

 intervals, or characterized by a narrow folded belt of Carboniferous sedi- 

 ments, as in the Worcester basin on the eastern limit of the flattish belt 

 of schistose rocks. 



On the extreme west, in the Hudson Valley and at various points, west- 

 ward overthrusting of strata as old in age as the Ordovician has long 

 been known. This forms a segment of the extended line of Appalachian 

 structures displaying the westward overthrust on the western side of that 

 mountain system, which has given rise to such explanatory phrases as 

 ''westward thrust from the Atlantic basin," implying that the middle and 

 eastern parts of the Appalachians participated in the same movement 

 and displayed the same westward overturning of folds and shearing 

 movements. 



To the east of these westward thrusts, in the Taconic Range, the Grev- 

 lock ^lountain section, as drawn by Pumpelly, Wolff, and Dale, shows the 



