I 76 WILLIAM H. HOBBS 



the structure of the apparently anticlinal ridges of Berkshire 

 schist could be determined with certainty. In the ridge of 

 schist immediately to the south of the east Twin Lake in the 

 township of Salisbury and in the mass of Tom Ball near Housa- 

 tonic village the observations obtained have been sufificiently 

 numerous and reliable to show that the folds are either over- 

 turned anticlines with easterly dipping axial planes or nearly 

 recumbent fanned synclines with the axial planes inclined to the 

 eastward. In Tom Ball attempts to follow the fold in the direc- 

 tion of the strike taking note of the pitch of the axis with a view 

 of determining whether the surrounding limestone goes below 

 or above the schist on the end of the fold, afforded no positive 

 results. On the other hand the ridge south of Twin Lakes was 

 followed southward into Watawanchu Mountain where the lime- 

 stone can be seen to pass under the schist on the end of the 

 fold. This latter locality is therefore a crucial one and shows 

 that the apparent anticlines of schist are nearly recumbent syn- 

 clinal folds with the necks compressed so as to produce a fan 

 structure. 



Turnip Rock in Salisbury was shown to be a syncline by Dana, 

 and the writer has referred to it as one of the best observed 

 localities to show the superior position of much of the schist (for- 

 merly called Everett schist) to the valley limestone. A study in 

 detail of this hill shows that it is made up of a fold similar to 

 those of the apparent anticlines, though here the limestone com- 

 pletely surrounds the hill and dips so as to form a shallow basin. 

 The peculiar character of the fold is only revealed in the dips of 

 the schist high up on the slopes of the hill. 



In view of the definiteness of the above determinations it is 

 best to substitute for the local terms Canaan limestone and 

 Riga schist the terms Stockbridge limestone and Berkshire 

 schist, which they were supposed respectively to represent and 

 which they are now shown to be. The Egremont limestone 

 should be replaced by the Bellowspipe limestone, which it was 

 thought to be, and its distribution is limited to that of the cal- 

 careous schist and limestone of the summit plain of Mt. Wash- 



