CONTRIBUTIONS 



HISTORY OF DERRYFIELD, 



BY WILLIAM E. MOORE. 



CHAPTER IV. 



ROCKS IN PLACE — BOWLDERS — THE SAND AREA — THE GREAT CLAY BEDS 



— VEGETABLE SURVIVALS — RHODODENDRON SWAMP — POT HOLES 



AND ROCK WEAR, ETC. 



Evidences of a former period of volcanic activity in this imme- 

 diate section are not wholly wanting, but it may be said roundly 

 that there is no such evidence manifesting itself to the untrain- 

 ed eye. We have no volcanic cones, no active or even extinct 

 craters, and no lava beds. Aside from the presence of altered 

 or metamorphic rock, and occasional trap dikes, we are aware of 

 no plutonic material in the region we have described. 



The rocks in place within a radius of ten miles, an area extend- 

 ing from the mountains on the west to beyond the water-shed 

 line upon the east — consist generally of mica-schist, gneiss and 

 granite, with the usual variety of quartzites. The principal 

 beds in Derryfield proper are composed of gneiss, or bastard 

 granite, and fine specimens of this archsean rock may be seen in 

 the pillasters of the city hall. Quarries of pure granite are rare 

 in this vicinity, although new ones are being from time to time 

 opened and developed. 



We are not without a large representation of travelled blocks, 

 and numerous enormous bowlders, which have been transported 



