Page:The Journal of geology (IA journalofgeology21894univers).pdf/439
the State. Between the areas indicated upon their map,[1] the writer has observed it or its metamorphosed equivalent, so it is known to extend in an unbroken line from near North Bennington the entire length of the State as a persistent characteristic horizon. At the Massachusetts line it is wanting where the Olenellus quartzite reposes discordantly upon a granitoid gneiss. On the east side of the range it is described by the above-mentioned authors as occurring in a narrow band running across the towns of Plymouth and Ludlow, and is correlated with the conglomerate horizon of the Rutland Valley. It is largely upon this eastern occurrence of the conglomerate that the anticlinal nature of the Green Mountains was hypothecated by them. The phenomena of stretching of quartz and gneiss pebbles in this horizon and their destruction thereby, furnished the elder Hitchcock with the necessary confirmatory data for his then revolutionary ideas concerning the production of gneisses from conglomerates by metamorphism. About one mile north of Tyson's Furnace in Plymouth and on the south slope of Bear Mountain in Wallingford occur the now classical localities where the conglomerate was most carefully studied by him and where nearly all his illustrations were obtained. It is doubtful if two areas can be found in metamorphic regions where the change of sedimentary rocks to crystalline gneiss is better or more satisfactorily shown. It was with fear and hesitancy that the question of this new effect of metamorphism was discussed, but the carefully-elaborated arguments advanced show that a keen appreciation of the proper interpretation of the phenomena revealed there was felt by the author of this most valuable contribution to the science of geology.
The first area described (the Wallingford locality[2]) is situated about where the 1500 feet contour makes a sudden jog to the south. Here the elongation and flattening of the pebbles, their contorted character and the transition of the rock to gneiss are remarked upon.