330 J. H. BRADLEY, JR. 



white quartz are frequently seen in the upper layers of A at East 

 Shoreham and Ai at Philipsburg. Near the top of this member at 

 both localities, large irregular masses of impure black chert occur. 

 The most striking similarity in the two members is the apparently 

 complete lack of fossil remains. The thicknesses given for the 

 respective members are 310 feet and 400 feet. The former probably 

 represents the entire thickness at East Shoreham. Logan's esti- 

 mate, on the other hand, cannot give indication of the true thickness 

 because of the overthrust fault cutting off the base of the section 

 at Philipsburg, and because of faulting and close folding which 

 probably occur down the dip of the member, but which are not 

 clearly shown in available outcrops. It is probable, however, that 

 the Beekmantown strata thicken to the northeast. 



Overlying the lower zone in both the eastern and western terri- 

 tory is pure, predominantly dove-colored limestone. The thickness 

 for this bed is given as 295 feet at East Shoreham. This estimate 

 includes transition beds above and below, which are dolomitic. The 

 middle, however, is nearly pure limestone, and therefore a distinct 

 horizon in a section that is largely dolomite. This bed is represented 

 at Philipsburg by Logan's Division A2, estimated at 100 feet and 

 lithologically identical with the pure Hmestone facies of the middle 

 of Division B at East Shoreham. In both sections the Lower 

 Beekmantown is terminated by a series of red-grey to black dolo- 

 mites, magnesian limestones and sandstones from 200 to 350 feet 

 in thickness. 



The uppermost members of the Lower Beekmantown on both 

 eastern and western shores of Lake Champlain are, like the lower 

 members, quite devoid of fossils. It is interesting to note that the 

 only fossils reported from either region were derived from the middle, 

 pure grey limestone horizon; at East Shoreham Orthoceras primi- 

 genium Vanux., Cryptozobn steeli, and an indeterminate gastropod 

 of the Holopea type; and at Philipsburg, indistinct forms resembling 

 the genera Pleurotomaria and Holopea have been observed. 

 Although it would be dangerous to draw conclusions concerning 

 the exact age of these lower members on such a scant faunal basis, 

 it is true that what fossils do occur are prophetic of a later Ordovi- 

 cian fauna and not reminiscent of any known Upper Cambrian forms. 



