102 Dale— Ordovician Outlier at Hyde Manor in Sudbury. 



Cambrian, the refolding of these formations at the close of 

 Ordovician time having in other places obscured any original 

 divergence in their strike. As on the eastern side of the Cam- 

 brian belt, 2 miles nearly ENE. of the outlier, Cambrian and 

 Ordovician are also in marked unconformity, a westward thrust 

 of the Cambrian on the west side is not consistent with an 

 eastward thrust of it on the east side, which the proposed 

 "Fenster" theory would involve. Minor faulting may well 

 have occurred on both sides in the refolding of two unconform- 

 able formations, but it was a secondary element. The prime 

 factors in the relations of the two formations are : a crustal 

 movement at the close of Lower Cambrian; emergence and 

 erosion of the Cambrian beds, followed by their submerg- 

 ence and the transgression of the Ordovician, and finally 

 another crustal movement, but at a slightly different angle 

 from the earlier one, which refolded both formations. 



The little outlier is a structural specimen, still in situ and 

 small indeed, but preserving the record of one transgression, 

 two crustal movements, and two periods of erosion which 

 affected several hundred square miles of the Taconic region. 



Pittsfield, Mass. , 



Dec. 16, 1911. 



