16 J. Barrell — Relations of Subjacent Igneous 



The metamorpliism of the Paleozoic sediments is in- 

 tense. The Lower Cambrian sediments, originally 

 feldspathic muds, have been transformed into lustrons 

 mnscovite schists, microcline gneisses, and quartzites. 

 The schists are closely crumpled, and show segregation 

 lenses of quartz, holding needles of tourmaline. The 

 Cambro-Ordovician limestone has become a white or 

 mottled marble holding mica and tremolite. Quart zitic 

 bands in places include needles of tourmaline. The 

 Berkshire schist in the eastern outcrops shows coarse 

 crystallization and the development of garnet and stauro- 

 lite. In the axis of the synclinorium, however, the meta- 

 morpliism of this rock dies out rapidly, and it turns to 

 a grayish or greenish sericite schist. In New York State 

 it passes gradually into the dark Hudson River slates. 



It would seem that here the severity of the deforma- 

 tion is roughly in accord with the degree of meta- 

 morpliism and is a sufficient explanation of the facts 

 without invoking the aid of magmatic heat or emanations. 

 Closer observation shows, however, a lack of exact accord 

 between the local degree of deformation and the local 

 degree of crystallization. The small synclines of Berk- 

 shire schist in the middle of the limestone valley show 

 strong metamorpliism even where not intensely deformed. 

 The pinched axis of the syncline, although of the same 

 stratigraphic level, shows a lesser degree of metamor- 

 phism. The limestone beds, even where flat-lying and 

 showing the bedding fairly undisturbed, are nevertheless 

 transformed into coarse marbles. The rocks of the valley 

 have, however, been deeply buried beneath overthrust 

 masses so that the greater depth at which they were 

 deformed must have been a contributory factor in the 

 metamorphism. 



Turning to another side of the problem, what is the 

 evidence or lack of evidence that batholithic intrusions 

 may lie below? The nearest Paleozoic granites, as 

 mapped by Hobbs,^ lie on the axis of the anticlinorium 

 some tw^elve miles south of the Connecticut-Massachu- 

 setts line. None are known in the synclinorium. Direct 

 evidence is therefore lacking. The indirect evidence is 

 as follows : The Lower Cambrian Dalton schists overlie 

 the Archean complex and outcrop in anticlines within the 

 limestone valley. They vary from muscovite schists to 



°W. H. Hobbs, in Preliminary geological map of Connecticut, by H. E. 

 Gregory and H. H. Eobinson, Conn. Geol. Nat. Hist. Survey, Bull. 7, 1906. 



