26 STRATIGRAPHICAL GEOLOGY. 



to the south in Sunderland, agreeing with the representation on Section III of Vermont. 

 The relative positions of the formations are the same all along this line. This quartz- 

 ite carries the ScoUtJucs linearis, and on that account was believed by Prof. James Hall 

 to be of Potsdam age. Billings regards it as the lower Potsdam, as the ScolitJms is a 

 different species from the one common in this sandstone in Canada. Logan represents 

 this rock as of the same age upon his maps of iS6S and 1869, but I understand he more 

 recently expresses the opinion that it belongs to the upper part of the Quebec group. 

 Others sympathize with this view. Granting the correctness of our section, in accord- 

 ance with the early views of Hall, it would indicate the presence of two shore lines in 

 the Cambrian period, in this part of the country. The one beach reposed upon the 

 west flank of the Green Mountains. The other, possibly connected by deep sea sedi- 

 ments of the same age with the first, was deposited at the eastern base of the Adi- 

 rondacks, especially in the neighborhood of Lake Champlain. 



The next formation is the Eolian limestone, probably of the Quebec group. In the 

 North Dorset valley a segment of it has been thrown upon end, but the normal position 

 appears in Eolus and Danby mountains, where about two thousand feet of limestone 

 repose horizontally, overlaid by talcoid schists. The basal layers approximate to quartz- 

 ite, some observers insisting that they have identified the latter rock among them, 

 which is made to appear beneath the surface in our representations. The upper part 

 of the limestone consists of the two thick layers of white marble, for which Vermont 

 is celebrated. Farther north, later studies indicate that the marble caps the limestone 

 series. Billings describes unmistakable Chazy fossils from near this marble layer in 

 West Rutland. The continuation of the beds to the extreme north also connects them 

 with layers abundantly charged with characteristic fossils of the lower Quebec group. 

 The rock is the same also with the Auroral limestones of Pennsylvania. 



The top of Danby mountain, shown a little farther to the south, consists of the same 

 schists, apparently, with those of Haystack mountain. These latter beds have an ap- 

 parent dip beneath the limestones. It is therefore necessary to believe in the existence 

 of a fault in the valley between the two mountains. This is the more easy, since the 

 Danby Mountain limestones and marbles do not continue uninterruptedly to Rutland. 

 The enormous lateral pressure caught the thick Taconic sediments in a most powerful 

 vise, as it were, between the Adirondacks and Green Mountains. Hence the interven- 

 ing valley is filled with faults and upheavals, usually very marked in the limestones, 

 because they are not so strong as the schists, and give way more easily. The Eolus 

 and Danby Mountain mass, like the precisely similar synclinal piles of Equinox, 

 Anthony, and Greylock mountains, happened to be forced upwards in the shape of 

 an immense cuneiform segment. The Danby marble layer is more than twelve hundred 

 feet higher than the same bed in Wallingford, four or five miles distant. 



The limestone often crops out to the west of the Haystack range, though never so 

 extensively as on tlie east. It is most extensively developed in this position at the 

 northern extremity of the schists near Sudbury. The stone is filled with veins of cal- 

 cite, so as to make the name of "sparry" appropriate. The limestone of this kind on 



