MUSEUM OF COMPARATIVE ZOOLOGY. 41 



Wherever the direct contact was found, liowever, namely, in the southeast 

 corner of the town of Lebanon, and at Humphrey's Quarry, in the southern 

 part of the town oi Pittsfiold, the folia of the mica schist were found to lie in 

 planes parallel to the planes of hedding of the limestone, and in the latter 

 locality the limestone and mica schist were ilistinctly interbedded. There is 

 every appearance, throughout the region, of the different formations being con- 

 formable with each other, and they are so represented in the section below the 

 large map. 



In all parts of the region where good observations could be taken, with one 

 exception, the rocks dip steeply in directions between E. S. E. and east. Thex'e 

 are irregular variations of'the dip ranging from 30° to 80' in different parts of 

 the same formation. The average dip along the section is about 60°, and, pro- 

 vided there were no faults or folds in the region, the beds would have a thick- 

 ness of 34,000 feet, or about 6^ miles. An exception to the almost universal 

 easterly dip has been alluded to. This exception occurs in the vicinity of Mr. H. 

 Salmon's house, near the northwestern border of the Richmond limestone area. 

 In a small ravine just west of Mr. Salmon's is to be seen an anticlinal arch in 

 the limestone, the axis running N. N. E., and a quarter of a mile northeast of 

 Mr. Salmon's is a portion of another anticlinal, the axis of which is parallel 

 to, and about a quarter of a mile east of that of the former. 



According to Professor J. D. Dana (" Geology of Vermont and Berkshire," 

 Amer. Jour. Science, July to October, 1877) the limestones of Berkshire 

 County lie in extremely eroded anticlinals, while the schists occur in the shape 

 of less eroded synclinals which rest conformably on the limestone. Different 

 degrees of flexure in the anticlinals and synclinals are to be observed in different 

 localities throughout the county, in some of them the flexure being so extreme 

 that the strata are folded double, with the planes of the folds dipping to the 

 east, the strata of those portions of the folds which have not been removed by 

 denudation presenting the appearance of interstratification. 



So far as the facts observed in the region of the Richmond Boulder Trains 

 are concerned, it seems that the structural relations of that region may be ex- 

 plained in accordance with Professor Dana's view.s. The three great masses of 

 schist in the three parallel ranges lie in extremely flexed synclinals, which are 

 contained between the anticlinal folds of the three great limestone belts. The 

 limestone belts are continuous with each other beneath the ridges of schist, and 

 the different masses of schist were once a continuous stratum overlying the 

 limestone, but have become separated through the loss by denudation of the 

 anticlinal portions of their folds. 



According to Professor Dana,* the Berkshire limestones are part of the con- 

 tinuous belt of tliat rock which extends through the western ])art of Connecti- 

 cut, Massachusetts, and Vermont, the portion in Vermont being called the 

 Eolian limestone. The limestone in Massachusetts is of the same age as the 

 Eolian limestone in Vermont. From the fossils discovered in the Eolian lime- 



Amer. Jour. Science, Vol. XIV., 1877, p. 37. 



