ALG ONKIA N RO CKS IN VERMONT. 425 



tions, now in the geological exhibit of the Agassiz Museum, 

 Cambridge, Massachusetts, Fig. 2. A fair percentage of the 

 pebbles are of a composite nature (gneiss) and as would 

 be expected, they have yielded most easily to the deforming 

 forces. They now form in large part with secondarily-developed 

 green muscovite, feldspars and cement of the pebbles, the more 

 schistose folia of the rock. Stretching and flattening have resulted 

 from a force operating along the plane of bedding in the direc- 

 tion of dip. The pebbles have been elongated most in an east 

 and west direction, and their perceptible flattening indicates that 

 this elongation took place under enormous load ; an environment 

 unlike that of the pebbles at South Chittenden, which have 

 undergone elongation without marked lateral yielding. The 

 environment factors here were probably extreme load, a force 

 tending to push the rock as a whole towards the west, and the 

 presence of water charged with inorganic compounds that pro- 

 moted the alteration of the clastic feldspar material, already 

 weakened by sub-aerial decay to more stable compounds under 

 the changed environment, and at the same time cementing the 

 mosaic of quartz and feldspar grains resulting from the enforced 

 granulation into a coherent rock. It seems unnecessary to pos- 

 tulate a high degree of temperature to account for these phe- 

 nomena ; nor has plasticity, as properly defined, played any 

 part in the deformation of the quartz and gneissic pebbles. 



At North Sherburne a conglomerate occurs of considerable 

 thickness and extends south to Ludlow, a distance of twenty-five 

 miles. It is fully as persistent on the east side of the range in 

 the area under discussion, as on the western, and, although some 

 phases are unlike the western belt as a whole, it may be safely 

 correlated with the conglomerate-gneiss horizon making, as first 

 suggested by Adams, an anticlinal axis between Plymouth and 

 Rutland valleys. 



The question of the relations of the conglomerate-gneiss to 

 the lower or Mount Holly rocks, has been most carefully studied 

 on the western side of the range where the country is more open. 

 At East Clarendon ; just north of South Chittenden, and at Hitch- 



