THE GEOLOGICAL STRUCTURE OF THE HOUSATONIC 

 VALLEY LYING EAST OF MOUNT WASHINGTON. 1 



(With Plates V, VI, VII.) 



Published with the permission of the Director of the United States 

 Geological Survey. 



CONTENTS. 



Introduction. 



The area studied. 



Views of Percival and Dana regarding the area. 

 Lithological characters of the horizons. 

 Explanation of map. 

 Geological structure of the area. 



Structural features as shown in longitudinal sections. 



Structural features as shown in transverse sections. 



Structure of Tom's Hill. 



The great Housatonic Fault. 



Metamorphism along the fault. 

 Thickness of the Egremont Limestone. 

 Conclusion. 



In a former paper 2 I have discussed the geological struct- 

 ure of Mount Washington and shown that in that mass we have 

 to deal with a conformable series of beds embracing four distinct 

 lithological members. These members are: (i) a lower dolo- 

 mitic limestone — the Canaan Dolomite ; (2) a lower schist 

 member containing usually abundant garnets and frequently also 

 staurolite — the Riga Schist ; (3) a calcareous member, in the 

 valley a marble but on the summit plain of the mountain and 

 along its base very micaceous and graphitic — the Egremont 

 Limestone ; and (4) a schist member very feldspathic and 



1 Part of a report of work done as Assistant Geologist in the Archean Division of 

 the U. S. Geological Survey, under the direction of Professor Raphael Pumpelly. 



2 On the Geological Structure of the Mount Washington Mass in the Taconic 

 Range. Journal of Geology, Vol. I., p. 717. 



780 



