438 TACONIC ROCKS. 



as it enters Canada. All the rocks included between these two lines belong to the Taconic 

 system, except the Trenton limestone in Highgate, the red sandrock series, and probably 

 several beds of Eolian limestone in Sudbury, containing Stromatopora, etc. 



The black slate shows itself along the western border of the system, and may be seen 

 underlying the Potsdam sandstone unconformably from Canada to Orwell. The promi- 

 nent localities for displaying the junction, are at Highgate Springs, at many localities 

 between Highgate and North Colchester, at Lonerock Point in Burlington, and on the 

 west side of all the summits of the red sandrock range, between Charlotte and Bridport. 

 In the west part of Benson, and the east of West Haven, this rock appears, uniting the 

 slate beneath the Potsdam sandstone in northern Vermont, with that at Bald Mountain 

 in Greenwich, N. Y. 



All of the clay slates west of the Potsdam sandstone range in northern Vermont, which 

 are not the black slate, are the Taconic slate. But the greater part of the Taconic and 

 roofing slates are found east of the sandstone. They are the Georgia slates of this Report, 

 and are consequently located in three different terrains : one in Franklin County, one in 

 Chittenden County, and one in Rutland County. 



The sparry limestone is found chiefly in Rutland and Addison Counties, extending 

 from Sudbury to Poultney River in West Haven and Fairhaven. Most of the fossils 

 from the Eolian limestone belong to this rock. Another mass of sparry limestone is 

 seen in Shaftsbury, Sandgate, Pawlet and Ira. This is inclosed by the magnesian slate. 



The magnesian slate is in two large deposits, with several outliers. The most distinc- 

 tive is the southern one, extending from Pownal to Pitts ford, lying just east of the 

 Taconic slates. It corresponds exactly to the talcoid schists of this Report. The northern 

 deposit of magnesian slate is the talcose conglomerate of this Report, extending from 

 Lincoln to Franklin. It is largely composed of conglomerates, which are not unknown 

 in the southern deposit. 



The Stockbridge limestone, corresponding very nearly with the Eolian limestone of this 

 Report, appears now in two isolated terrains, but they are connected beneath the Potsdam 

 sandstone of Monkton. This limestone occupies the great valleys west of the Green 

 Mountains. We are at a loss whether Prof. Emmons would consider the white limestones, 

 so gently overlying the red sandrock in Burlington and Colchester, as the Stockbridge 

 limestone. We suspect, from its position, it might be regarded as lower Silurian (by 

 his theory) in a metamorphic state, because it so distinctly overlies the Potsdam 

 sandstone and calciferous sandstone of Burlington, although it contains no fossils, unless 

 it be obscure Chaetetes and Stromatoporse. The pure, dove-colored limestone of Col- 

 chester might be the Birdseye limestone. We do not regard this limestone as the same 

 with that west of the red sandrock, though their lithological characters are the same. 

 The one is above and the other below the red sandstone ; yet, as a profusion of faults and 

 foldings are necessary to sustain the Taconic system, a few might be imported to make 

 this point clear. In that case it would be a bed of limestone in the Taconic slate. 



We think that there is a great resemblance between this limestone at Burlington and 

 one described under No. 6 of the gray sandstone, described in Emmons' Geology of the 

 Second District of New York, page 125. There is something Avanting in the report, and 

 we cannot decide from the statements whether this limestone is No. 3 of the gray sand- 



