444 POSITION. 



The other locality referred to is at Highgate Falls, where the calciferous sandstone 

 overlies the black slate. The Missisco River passes through a gorge, just below the vil- 

 lage, where a junction of the two may be seen at low water. The rocks both clip in the 

 same direction, but the angle of inclination of the slates is greater than that of the sand- 

 stone. The calciferous sandstone appears to rest in an irregular trough in the slate, and 

 also upon its edges. The strata of slate in some places are bent at the junction, owing to 

 forces which have been communicated to the rocks. And there seems to be an anticlinal 

 in the slate, while the sandstone rests upon its top upon both sides of the axis. This 

 fact makes it certain that the sandstone and slate form two distinct groups of rocks, viz., 

 Silurian and Taconic. 



Similar sections might be multiplied, but it is clear that the calciferous sandstone and 

 Potsdam sandstone overlie the black slate of the Taconic system. Hence the upper limit 

 of the system is well denned. 



THE ORIGINAL POSITION AND SUBSEQUENT DISLOCATIONS OF THE DIFFERENT MEMBERS 



OF THE TACONIC SYSTEM IN. VERMONT. 



Supposing that there was but little disturbance of the strata until the close of the Ta- 

 conic period, the original position of its members is quite plain. The Laurentian rocks 

 of the Green Mountains were the ones upon which the Taconic rocks were placed, just as 

 the Silurian rocks encircle the Laurentian rocks in Northern New York. The first rock 

 deposited rested upon the western flank of the Green Mountains, dipping westerly. 

 Probably the whole of the great valley west of the mountains was underlaid with this 

 rock. IJpon this was deposited the Stockbridge limestone, then the magnesian slate, and 

 so on to the black slate. All these rocks had a gentle westerly dip. It is not to be sup- 

 posed that each member should entirely cover up all those below it, any more than that 

 the Oneida conglomerate in New York should conceal the Trenton limestone so that no 

 traces of the latter could be found. Neither is it necessary to suppose that the lower 

 members underlie the whole area covered by the upper members. In these respects the 

 parallel between the New York and Taconic systems is perfect. 



But the Green Mountain range begins very early to press against this system of rocks, or 

 in other words the lateral pressure from a southerly direction was more thoroughly ex- 

 erted in this region than at any other point between Lake Champlain and the ocean. 

 Instead of a series of beautiful curves, as appears elsewhere, the great pressure seems to 

 have broken up the strata, so that the force relieved itself by lifting up mountain masses 

 and crowding them together, at the same time giving an easterly dip perhaps inverted 

 to most of the members. Such masses of the strata as Mounts Eolus and Equinox 

 seem to have pushed up, just as a wedge may be conceived to be forced back from its 

 position by pressure against its sides. As the result of this pressure the granular quartz 

 would be crowded high up on the west flank of the Green Mountains, and form a high 

 ridge. It might often be elevated higher than the rocks stratigraphically above it. At 

 the same time some of these fragments may have sunk instead of rising. 



Prof. Emmons supposes that in general there are four or five of these masses of strata or 

 segments, separated by faults. In general the segments are composed of older and older 

 rocks, as we travel east from the Silurian rocks, though without the knowledge of dislo- 



