T. X. DALE — THE STOCKBRIDGE LIMESTONE. 



>1 t 



In section ( ', about three-quarters of a mile farther norl hi ward, the quartzite over- 

 lies the schist.* 



In section D, south of .1 and about half a mile south of the deepest part of the 

 saddle, a block of the schist which belongs over the limestone is wedged in between 

 quartzite masses. The structure is like that in section .1. but occurs higher up the 

 hill where the schists have escaped erosion. 



Section E is longitudinal, from the deepest part of the saddle northward. Owing 

 to the northerly pitch of the anticlinal at this point, together with the deep erosion 

 of the ridge, the entire thickness of the limestone from the quartzite to the schist 

 is here exposed along a north-south line, and the three rocks are seen in their 

 normal relations with well observed contacts. This section tlm- yields a measure- 



Figure G.—Structurt of Hyolith.es Limestone. 



ment of the limestone, which amount- to from 1,001) to 1,400 feet, according as the 

 average pitch is taken as 25° or 35°; 1,200 feet is probably correct. 



Tin upper Part of thr Limestone "ml tin- Schist. — The northeastern corner of the map 

 (plate Ki; overlaps the extreme southern end of Mr. Wolff's map and includes the 

 fossil locality given by him southeast of Clarendon Springs, where Mr. Aug. F. 

 Foerste found in a sandy limestone "crinoid stems and plates and a small blanch- 

 ing bryozoan with large cells. "t This locality (339 on map) is in a small lenticular 

 area of limestone surrounded by schist, the former of which may be regarded either 

 as representing the schist by different sedimentation, and thus of the same age as the 

 schist, or as a minor anticlinal in the uppermost part of the Stockbridge limestone. 

 During the past summer Mr. Foerste found fragments of crinoid columns and a 

 Heliolites f (Walcott's determination) in a similar but smaller limestone area 260 

 on map) within a few feet of the fault. This from its position can hardly belong 

 to the limestone, but must represent the age of the schist. Mr. Foerste also found 

 on the eastern side of the ridge, near South Wallingford, in the limestone near the 

 schist, besides the usual crinoid stems, the following: Streptelasma, sp. ? ; a coral 

 much like Heliolites; and cross-sections of strophomenoid shells — all determine. I 

 by Mr. Walcott, who refers the fossils generally to the Chazy-Trenton-Lorraine 

 faunas. 



from all these facts it follows that the upper part of the limestone and certainly 



a portion of t he overlying schist are of Lower Silurian age. 



'/'/,, /■'(in/I. — As will he seen by examining the sections, the amount of displace- 

 ment along the fault plane equals the entire thickness of the limestone, besides 

 aboul 300 feet of the overlying schists.;.,.. 1,500 feet. The line of the fault is 

 marked in places by large quartz veins and on Pine hill by eruptives. The fault 



can he followed to a point west of South Wallingford. < Ml the southern side of 



• The structure here m >>• even be more extreme than 9hown in the section. 



1 Op. oil ,p 131 



LXX— Bi i,i.. fJnoi . Boi . Am.. Vol. ::. 1891. 



