428 THE JOURNAL OF GEOLOGY. 



pleochroic muscovite, that characterizes the conglomerate-gneiss 

 horizon and give to it its greenish color, the result of alteration of a 

 potassium feldspar during dynamic movement. Its other con- 

 stituents seem to be identical with the neighboring gneisses, but 

 on so slim a basis it is not deemed safe to refer the elastics to 

 any particular gneiss area in the Mount Holly series. The feld- 

 spar elastics appear to have been derived from the pegmatite 

 veins that are very abundant in the lower rocks to the east. 



The Bear Mountain locality in some respects is more import- 

 ant in its bearing on the question of non-conformity than the one 

 above described ; no one area furnishes the data for all the con- 

 clusions to be drawn from the horizon. Attention was first called 

 to the abundance of small clastic pebbles of feldspar occurring 

 there, by Edward Hitchcock in i86i,^ and in 1891, by Mr. 

 Wolff.'' As remarked by Mr. Pumpelly,^ there seems to be "no 

 other source than the debris of the deeply decayed Mantle" on 

 which the conglomerate was lain down, and as such they point 

 to a land surface close at hand where sub-aereal decay had weak- 

 ened the cohesion of the rocks, permitting a positive movement 

 of the sea to build the more superficial mantle containing the 

 feldspar grains, and a lower semi-disintegrated zone of gneiss and 

 loosened blocks of gneiss into' a conglomerate. The phenome- 

 non of false bedding is well shown here, and was figured by 

 Hitchcock-* ; transitions from coarse sediments, when the pebbles 

 of quartz attain a diameter of nearly a foot, to fine material, 

 point to the ordinary conditions obtaining along our coast. So, 

 too, the outlines of the elastics are those that are characterist- 

 ically produced by wave action, unless deformation has taken 

 place, which is usually the case at this locality. All these facts 

 are subordinate in their value compared to the conclusion to be 

 drawn from the conglomerate-gneiss horizon as a whole, extend- 

 ing as it does across the State of Vermont, and presenting in one 



'Opus. cit. p. 34. 



2 Metamorphism of Clastic Feldspar in Conglomerate Schist. Bull. Comp. 

 Zool., Vol. XVI., pp. 173 to 183. 



3 Opus, cit., p. 211. 

 *Opus. cit., p. 32. 



