40 THE STRATIFIED ROCKS OF ESSEX COUNTY. 



On Kent's Island in Newbury, at the junction of Little 

 and Parker rivers, there is a bed of argillite interstratified 

 with sandstone which extends about one thousand yards on 

 the bank of the Parker river to a point near the Eastern 

 Railroad and on Little river one hundred yards west. 

 Some of the beds are of a dull red color resembling the 

 North Attleboro and North Weymouth slates while others 

 are of a greenish color. They are cut in several directions 

 and are distorted by felsites and amygdaloidal melaphyrs, 

 shearing and faulting to such an extent that the true bed- 

 ding is quite difficult to determine. By uncovering the 

 glaciated surface, however, and washing away the clay and 

 drift the bedding is plainly revealed. The strike is 50 

 north of east, dip 55 southwest. The microscopic struct- 

 ure of a very opaque section of the red slate, cut across 

 the bedding is : clastic quartz grains and fragments show- 

 ing secondary enlargement and' crushing and containing nu- 

 merous fluid inclusions, surrounded by a ground-mass of 

 earthy kaolin, much muscovite and ferruginous magnetite 

 and limonite. The sections of the green slate from Little 

 river are composed of angular and rounded quartz grains, 

 a finely fibrous kaolinized ground-mass, some epidote, mus- 

 covite, a few grains of zoisite and much chlorite. The al- 

 ternating sandstone is composed of quartz and feldspar 

 grains, some biotite and scales of rnuscovite and much fer- 

 retic oxide. 



In Andover, near Butterfield's saw mill, is an outcrop of 

 metamorphic micaceous sandstone lying parallel to the horn- 

 blende schist on the east ; this formation is again found at 

 John Jenkins' farm near the cross road to Ballard Vale. 

 The microscopic structure of sections from these outcrops 

 is : quartz grains of original sand cemented by a film of fer- 

 reous oxide and some secondary quartz, scales of muscovite 

 and biotite and masses of fibriolite. One of the sections 



