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CONTENTS 



Page. 



Letter of tra>smittai xxi 



Chapter I. — Introduction I 



Area covered 1 



Historical sketch 2 



Chapter II. — Topography 8 



Chapter III. — Geological outline and general comparative sections 12 



General comparative section of rocks in Massachusetts 16 



Chapter IV. — The Algonkian 19 



Geological description 19 



The Hinsdale area 19 



The Coles Brook anticline 21 



The Tolland area 24 



Petrographical description 24 



Lower or Hinsdale gneiss, Hinsdale station 24 



The Hinsdale limestone, Hinsdale 25 



The Coles Brook limestone 27 



The blue- quartz gneiss, Peru 28 



The Lee gneiss 29 



Resume 30 



Chapter Y. — The Lower Cambrian gneisses 31 



The Becket conglomerate-gneiss 31 



Contact upon the Washington gneiss below 31 



Description of the rock 32 



Distribution 33 



Petrographical description 34 



Crushing tests 36 



The gneiss at Shelburne 38 



The Monson gneiss and associated rocks 41 



The Pelliam and Wilbraham area 42 



The gneiss 42 



Petrographical description 43 



The actinolite-quartzite 4.5 



Petrographical description 46 



