GEOLOGICAL RELATIONS. 25 



of Marlborough. On ascending the ridge west from Keene, we find the Cheshire Rail- 

 road has cut through the ledges very extensively, thus affording excellent means for 

 determining the position. In the first considerable excavation the strata are extremely 

 variable in jjosition and character. First, there is a reddish gneiss. Next, a quartz 

 band breaking into jointed rectangular fragments. Thirdly, there is a chloritic rock, 

 standing nearly vertical. In the "mile cut," in the south corner of Surry, the first 

 rock is hornblende schist, dipping N. 60° W. The second is chlorite schist; then 

 twenty or thirty feet thickness of quartz. Gneiss succeeds, with numerous irregulari- 

 ties, but with the more common dip of 20° N. 60° W. The Cous rocks are mainly 

 quartzites, with a high north-westerly dip, and they are unusually well developed in 

 Westmoreland. 



The facts concerning the section between Connecticut river and New York are 

 derived from the Vermont report, mainly from Sections IV and V. In Putney, late 

 observations indicate the presence in the clay slate of an anticlinal axis, showing that 

 this formation is probably older than the adjoining schists. Upon this theory, the east- 

 erly dip of the western border of the slate must be an overturn. The two axes in the 

 Calciferous mica schist are given from the appearance in Sections I, II, and III, and 

 the Black Mountain granite is represented in the ridge of the anticlinal. Next succeeds 

 the Atlantic gneiss, — perhaps Montalban, with several folds. Three important anti- 

 clinals appear. The first occurs on each of the six lower sections of the Vermont 

 report. Between the first two anticlinals is a band of Huronian, perhaps a synclinal, 

 as there are magnesian bands near both the borders. It is the main hydro-mica schist 

 range of Vermont lying east of the Green Mountains. In Londonderry the gneiss is 

 more largely feldspathic than usual, and presents some points of resemblance to the 

 Lake gneiss or the Laurentian. The axis along the main range of the Green Moun- 

 tains in Peru and Dorset is very clearly indicated in the outcrops, thus corresponding 

 with its usual structure, displayed most satisfactorily, however, where the range has 

 been cut down by the passage of the Winooski and Lamoille rivers. This axis is 

 often an overturn, the strata being apparently monoclinal. 



After passing the Green Mountain axis, we are brought into contact with what have 

 been known as the " Taconic rocks," and into a region of gigantic upthrows and down- 

 throws, which have occasioned much difficulty in the unravelling of the structure. I 

 may not satisfy all with the interpretation given to the structure of these rocks, but 

 present that view which seems most correct. The quartzites of East Dorset and West 

 Peru dip westerly when in contact with the gneiss. The western border has an east- 

 erly dip, so that the structure is synclinal. The eastern part is much more elevated 

 than the western, so that our band itself is inclined, much like the new moon in the 

 position supposed by many to indicate a wet month. The same view of the position of 

 the quartz and its relations to the gneiss is given in Dr. Asa Fitch's section, in his 

 paper in Trans. N. Y. State Agr. Soc, 184-D. His section crosses the same formations 

 in Winhall, the next town to the south of our section. By way of further confirma- 

 tion, it may be said that Emmons figures a similar state of things about twenty miles 

 VOL. II. 4 



