THE STRATIFIED ROCKS OF ESSEX COUNTY. 39 



The microscopic structure as shown by five sections of this 

 metamorphic slate from East Haverhill is : angular and 

 rounded grains of quartz in some of which there are nu- 

 merous fluid inclusions, several quartz grains in the line of 

 the schistosity of the rock-mass showing cracks from all 

 the incipient stages to the broken and crushed masses, feld- 

 spar grains much kaolinized and showing the effect of 

 crushing, some of the grains being broken into several 

 pieces, scales of muscovite and biotite arranged in layers 

 parallel to the schistosity of the rock-mass and inclusions 

 of apatite, zircons, fibriolite and rutile abundant in the 

 kaolinized feldspars. Titaniferous magnetite and leucox- 

 ene are scattered through the sections and fine acute 

 rhombs and long lath-shaped sections of titanite are seen 

 in one of the thin sections. 



The microscopic structure of the metamorphic slate in the 

 bed of the Merrimac river below the Lawrence dam is : 

 clastic grains of quartz sand, some secondary quartz sur- 

 rounded, with earthy yellowish kaolin and chlorite masses, 

 titaniferous magnetite and leucoxene and a few grains of 

 plagioclase with inclusions of apatite, zircons and fibrolite. 



The quartz grains show evidence of crushing, embryonic 

 cracks are developed and some of the grains are broken 

 and the pieces faulted two and in one instance three times. 



Nearly all of the bed rock of Methuen is composed of 

 this metamorphic slate and a coarse mica schist of the same 

 composition as that from Lawrence, Haverhill and Gage's 

 Hill in Bradford. In Methuen this slate and schist is over 

 one thousand feet in thickness ; the trend is north 40 east 

 southwest, dip 45 west. Nearly every outcrop from West 

 Andover across Lawrence, Methuen, Bradford, Haverhill, 

 Merrimac, South Hampton, Hampton Falls and North 

 Hampton to Rye in this strike is composed of these same 

 metamorphic slates and schists. 



