236 GEOLOGY OF OLD HAMPSHIKE COUNTY, MASS. 



lu the center of the area the amphiboHte is brought up aloug the south 

 line of the town, as it seems to me, by a minor fokl. It may be traced 

 north nearly to North Orange. On the east of the anticline the amphibolite 

 appears in force at the third bend after passing the site of the old fort on 

 the road to Athol. 



The beds above the amphibolite, which represent the whetstone-schist, 

 are a fine-grained biotite-quartzite, having some resemblance to very fine- 

 grained varieties of the lower gneiss. Northward along the eastern border 

 the lower beds are everywhere covered b}^ the broad gravels of the valley. 



METAMORPHISM OF THE AMPHIBOLITE BAND AS IT IS INVOLVED IN THE GRAN- 

 ITITE OF THE ATHOL BATHOLITE, AND ITS LATER CHANGE TO STEATITE. 



The great bed of amphibolite which occurs east of Athol, and which 

 is in one place changed to steatite, can be followed a long way N. 20° W., 

 and after disappearing for a distance beneath the sands it ap^sears again in 

 the southwest shoulder of Tullys Mountain, east of North Orange, crosses 

 the great granitite mass like a bridge, and is continued beyond in the 

 schists, changing with their strike to the northeast. It mounts the steep 

 granite mountain side with a width of about 40 rods, and is well exposed 

 by the workings of the soapstone quan-y. The adjoining granitite is a 

 fine-grained biotite-granite, containing rarely large crystals of magnetite 

 and a little allanite. It shows a slight banding pai'allel to the contact with 

 the schist, and sends offshoots into the latter 



At the quarry the contact for a long distance runs athwart the folia of 

 the schists, and their twisted ends abut against the granitite and are parted 

 by it. The great mass of the hornblende-schist is changed into a coarse, 

 shining, dark-brown, massive gedi-ite' rock, containing small, fresh plagio- 

 clase grains, and abounding in small, sharp cubes of pyrite Avith truncated 

 corners, or a more friable dark-green aggregate of actiuolite needles. In 

 part, especially near the borders, the rock retains the banded appearance 

 which it has beyond the limits of the granitite. All the contact phenomena 

 are those of an eruptive rock upon a schist. In several places the massive 

 gedrite rock is further changed, in bands running about N. 70° E., into a 

 dark-green soapstone abounding in white dolomite, talc, and a green chloritic 

 mineral. In some places there are, over broad surfaces, plates of clinochlore 



' For description and analysis see " Gedrite " in A mineralogical lexicon : Bull. U. S. Geol. Sui-vey 

 No. 126, 1895, p. 86. By mistake the mineral is assigned to Warwick instead of Orange. 



