THE LEVEKETT AMHEKST AEEA. 



221 



stratum in the Northfield Mountain. It abounds often in a green, cliloritic 

 mineral, and along the road east of Mount Tob}' it is abinidanth- l)recciated 

 and cemented by hematite. 



Along- the east .side of Mount Toby the whetstone -schist appears in the 

 base of the mountain. Its first outcrop is just south of the Mount Tob}' 

 station, and it can be followed fi'om this point south to the first brook, 

 where the contact of the Mount Tob>' conglomerate upon the whetstone is 

 40 feet above the railroad (436 feet above sea level), and on to the second 

 bi'ook, where the contact is 12 feet above the railroad. This greatly lessens 

 the probable thickness of the conglomerate of Mount Toby. 



In the extreme northeastern corner of Amherst there is by the roadside 

 a small outcrop of thin-fissile, stretched hornblende-scliist in the whetstone, 

 exactly resembling that found in the Northfield section. It can be traced 

 northwest jjast the brook-crossing east of A. Adams's house, and connects 

 with the bed at Leverett Center. It is a l)eautiful rock under the micro- 

 scope. The perfectly parallel hornblende blades have the strong pleoch- 

 roism and absorption of the Chester amphibolite, large, rounded grains of 

 magnetite are frequent, and the whole is placed in a background of 

 mitwinned feldspar grains. An analysis of the rock by Mr. L. G. Eakins is 

 given below: 



Analysis of hornblende-schist from Amherst. 



Per cent. 



SiO. I 47.56 



TiOj j 1.24 



AlA , 16.13 



Cr;0;i trace 



Fe^Oa 

 FeO. 

 MnO 



1.80 



9.39 



.08 



BaO I trace 



CaO 6.67 



MgO 9.21 



K,0 . 

 NaaO . 

 H,0. 

 P:0.i. 



1.58 



2.52 



.3.51 



.21 



