WALLINGFORD CONGLOMERATE. 



33 



Numerous bowlders are scattered over the field, which are instructive ; but the embossed 

 ledge half a mile north of Hager's is the most so. It has been rounded and smoothed by 

 the drift agency, so as to show the pebbles and their alternation with the schists very dis- 

 tinctly, as the foregoing sketch of a portion of the ledge, taken by one of our number 

 (A. D. H.),will evince. It will be seen that the schist, often containing small pebbles or 

 coarse grains of sand, is interstratified somewhat irregularly Avith the pebbles, just as we 

 often see in alluvial deposits and in sandstones that have not been metamorphosed. The 

 drift strife are quite distinct upon it, running southeasterly, as shown on the sketch. 



The strike of these strata is about N. E. and S. W., and the dip 70 W., but it some- 

 times rises to 90 in the vicinity. To show its position in respect to a micaceous quartz rock 

 approaching micaceous schist on the upper side, and to the Green Mountain gneiss below 

 it, we give the sketch beneath. These rocks constitute a single massive ledge with very- 

 few distinct strata seams, and they seem as if only varieties of the same rock. 



Fia. 9. 



Conglomerate and Talcose Schist. 



Talcose Schist. 



Gneiss. 



To show that the gneiss sometimes lies above the quartz and the schist, we give the 

 following section (Fig. 10), only a few rods long, taken at an easily accessible locality on the 

 east side of the mountain, where, as we shall shortly see, the same rocks occur in juxta- 

 position, on the road from Ludlow to Mount Holly ; and near the line between the two towns, 

 a small stream has cut a gorge, 40 or 50 feet deep, through a ledge of quartz rock. On 

 the west side a trap dike occupies a considerable part of the face of the rock, though more 

 or less worn away. Talcose schist succeeds the quartz rock on the west side, dipping 

 beneath it at a high angle. But on the east side, and lying upon the quartz at a less dip, 

 is distinct gneiss, with more of feldspar than is usual in the Green Mountain gneiss. 

 The section below will give an idea of these facts. 



Fio. 10. 



be d 



a, gneiss ; b, trap dike ; c c, quartz rock ; d, talcose schists. 



A. D. H. furnishes the following sketch (Fig. 11), showing the position of the talcose 

 schist and beds of quartz and limestone east of the ponds in Plymouth. These strata lie 



