54 NEW YORK STATE MUSEUM 



are packed away. The ever present effects of pressure have almost 

 always granulated the components and have turned feldspars, bisili- 

 cates and ores into lenticular interwoven masses. More complete 

 crushing, often accompanied by apparent flowage, has given swirl- 

 ing, gneissoid foliation and in the extreme has developed a decided 

 hornblendic gneis.. This curious and interesting variation of tex- 

 ture can be seen in the brook bottoms which enter the Boquet from 

 the steep mountains on the west, and above Elizabethtown. The 

 brook which comes in about 2 miles south of the village and along 

 the contact of the gabbro and syenite and with a trap dike across 

 its exit from the cliffs, gives very interesting exposures, and the 

 same is true of Roaring brook a mile to a mile and a half from its 

 mouth. The stringing out of the minerals may be in part a phenom- 

 enon of igneous flowage, but certain it is, that the textures vary 

 greatly within short distances and the rock, whether molten or 

 whether viscous from pressure, has not behaved as a perfectly 

 hydrostatic body. Buttresses or masses unaffected by the flowage 

 have remained in the midst of the generally plastic material. 



The component minerals of the gabbro are chiefly plagioclase, 

 augite, hypersthene, brown hornblende and titaniferous magnetite. 

 The less common ones are olivine and biotite. A widespread mem- 

 ber not truly original with the rock is garnet, which appears in the 

 reaction rims in a very interesting and at times remarkable manner. 

 The plagioclase is a basic variety, labradorite or one even lower 

 in silica. It is so charged with finely divided dusty inclusions that 

 it remains practically opaque in its central portions even in very 

 thin slides. The inclusions appear to be pyroxenic dust and minute 

 gre'en spinels, but they are so exceedingly small, and their optical 

 properties are so disguised by the containing feldspar, that their 

 sharp identity can not well be made out. Around the edges the 

 feldspars become clearer, and next the reaction rims of garnet they 

 are limpid and transparent and apparently are untwinned albite. 

 The lime component seems to have been contributed to the garnet. 

 The augite is, in the thin sections, light green in color and ap- 

 pears to be of the ordinary variety, often seen in the gabbros. 

 The hypersthene is widespread and frequently in sufficient amount 

 to make the rock a norite. It is in no way remarkable. The horn- 

 blende is of a deep brown variety, and increases greatly in amount 

 where metamorphism is more pronounced. Olivine is not specially 

 abundant. So far as studied, many exposures may entirely fail 

 to show it. It is pale green in color and customarily quite fresh. 

 The titaniferous magnetite is richly distributed through the rock. 

 It can be readily detected with the eye, and under the microscope 



