ELIZA BETHTOWN AND PORT HENRY QUADRANGLES 67 



direction of the master fault of the region. The most important 

 of these are found along the highway leading along the base of 

 the fault scarp near the upper stretches of Beaver brook and along 

 its branches. 



The Port Henry area of Paleozoic rocks contains at its north end 

 a most interesting exposure of Beekmantown rocks at both ends 

 of the railroad tunnel and especially along the shore to the east 

 of the tunnel and north of the same as far as Craig harbor. About 

 80 feet of division A are exposed in the cliff through v^hich the 

 tunnel has been driven. These, mostly the dark iron-gray dolo- 

 mites, characteristic of the division, exhibit heavy beds at the base, 

 that consist of rounded quartz grains cemented by a dolomitic 

 matrix and representing the basal beds of the formation or at least 

 indicating closeness to its base. The beds are frequently cross- 

 bedded, some show very irregular surfaces and bedding planes and 

 others display an irregularly nodular structure, while the beds rest- 

 ing on irregular surfaces contain pebbles of the underlying courses. 

 The beds of this subdivision bear here evidence of much dis- 

 turbed disposition, although much of the brecciated appearance is 

 undoubtedly due to later crushing of the beds [see below p. 91]. 

 In the railroad cut to the north of the tunnel the upper beds of 

 division A, marked by black chert bands, are seen, and beyond a 

 depression follow the purer limestones of division B which extend 

 as far as Craig harbor and are here quarried extensively to be 

 used for flux on account of their relative purity. This outcrop 

 complements to a large extent that of the Westport area, exhib- 

 iting the lower beds which there are only partly exposed. Neither 

 of the divisions showed any traces of fossils save fragments of 

 linguloids observed by Kemp and Matthew in the arenaceous basal 

 beds in the railroad tunnel, and the much disturbed condition of 

 the beds did not allow of reliable measurements of their thickness. 



The third appearance of Beekmantown beds on the sheet on this 

 side of the lake is that on Crown Point peninsula. Here only three 

 outcrops could be found, one on the shore of Bulwagga bay, an- 

 other near the road and a third in the middle of the ^east shore. 

 The first, as originally described by Brainerd and Seely and more 

 fully elaborated by Raymond, contains but the barren top layers 

 of the Beekmantown, while the others are fossiliferous outcrops 

 of the divisions D and E. 



In the first two outcrops only a few feet of a light-gray dolomite 

 are shown which are directly followed by the basal beds of the 



