PLATE X. 



A. Quartzite-conglomerate (Vermont formation), stone hill, Williamstown, Mass. Microphoto- 

 graph; polarized light, x -1. 



The shadowy area filling the left half is one of the masses of crushed hlue quartz which shows the 

 so-called "wavy" extinction in polarized light. At the top it is seen passing into the quartz mosaic of 

 the " groundmass." At the bottom and lower right side a crystal of microcline has been faulted 

 several times and the tine quartz of the groundmass penetrates it. 



B. Crumpled metamorphic conglomerate (Vermont formation). Hoosac mountain, blufiV south of 

 Spruce hill, near that of Fig. 1". About one-eighteenth natural size. 



These pebbles are granulitic and by pressure have been gently crumpled. This figure represent, 

 the transitional form between the conglomerate and the white gneiss; in the latter the granulitic 

 lenses remind us of pebbles, but they have lost their shape. 



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