LLUSTRATIONS. 



Page. 

 Plate I. Map of Grey lock and Hoosac mountains Frontispiece. 



II. General map showing the relation of the G reylock series to the Hoosac mountain 



rocks 10 



III. Structural relations of the Hoosac series 14 



IV. Detailed map of western crest and slope, Hoosac mountain 40 



V. Geologic profiles, Hoosac mountain 70 



VI. Geologic profiles, generalized, Hoosac mountain 80 



VII. Thin sections, white gneiss 110 



VIII. Thin sections, white gneiss and albite schist 112 



IX. Thin sections, diorite and ainphibolite 114 



X. Thin sections, quartzite conglomerate and crumpled metamorphic conglomerate 116 



View north over crest of Hoosac mountain 118 



XI. 



b ( Profile of Hoosac mountain from Spruce hill south, looking west 118 



XII. Mount Greylock, eastern side 130 



XIII. Mount Greylock, western side 132 



XIV. Southern summit of Mount Greylock 134 



XV. Southern side of Mount Greylock 136 



XVI. Southern end of Ragged mountain 160 



XVII. The north-south part of Hopper 192 



XVIII. Greylock sections, A, B, C, D 



XIX. Greylock sections, E, F 



XX. Greylock sections, G, H, I 



XXI. Greylock sections, J, K, L, M 



XXII. Greylock sections, N, O 



XXIII. Greylock longitudinal sections, P, Q, R * 



Fig. 1. The Stamford dike, showing the Cambrian conglomerate deposited in dike fissure 11 



2. The Stamford dike, plan 11 



3. Correlated columns of the Hoosac and (i reylock rocks 13 



4. Anticlinal arch across Hoosic river between North Adams and Briggsville 15 



5. Ideal section east of Cheshire, showing lateral transition of limestone to schist 17 



6. Diagram of structure, summit of the Buttress 22 



7. Crumpled structure in albite-schist 23 



8. Map showing the varying character of Cambrian rocks around the Hoosac core 31 



9. View from Hoosac mountain 42 



10. Profile of Hoosac mountain ( western crest) 43 



11. Profile of Hoosac mountain I \\ estern slope) 44 



11'. Granitoid gneiss 45 



VII 



