42 WILLIAM J. MILLER 
residue of the anorthosite-gabbro magma, or it was taken into 
solution by magmatic solvents during their passage through the 
anorthosite-gabbro after it was nearly or wholly consolidated but 
still hot. That the general rock mass was still hot during the intru- 
sion of the hornblendite dikes is proved by the fact that still later 
minor intrusions, as distinct facies of the anorthosite-gabbro, 
took place. In any case we are dealing with magmatic intrusive 
material (hornblendite) which should be classed as dike rather than 
vein material. 
FRACTURED AND CRUSHED ZONES 
A remarkable zone or belt of fractured, and in part crushed, 
anorthosite-gabbro occurs near the northern end of the area. It 
strikes about north 60° west and extends partly across the northern 
road near the granite contact at locality 2. This fractured 
zone maintains a fairly uniform width of about one rod, and it is 
very clearly exposed across a great ledge of bare rock for approxi- 
mately two hundred feet on the north side of the road. South of 
the road it shows much less. The main body of rock of this zone 
varies from nearly white anorthosite to light-gray anorthosite- 
gabbro. This zone is characterized throughout its length by a 
remarkable system of curving, roughly parallel cracks. Ina sense 
the cracks are festooned one within the other. This system of 
cracks extends across the zone of fracturing rather than parallel 
with it. Fig. 6 gives a fairly good idea of the structure, though 
the foreshortening in the picture is strong. The description 
immediately following pertains to this photographed locality 
twelve or fifteen rods north of the road. Between the cracks the 
distances generally range from one to six or eight inches. Most 
of the cracks (now filled) are from one-fourth of an inch to two 
inches wide, but they vary considerably even within a few inches. 
A single crack is seldom traceable for more than five or six feet. 
The cracks are filled chiefly with rather fine-grained, nearly pure- 
white, plagioclase-rich material. The walls of the cracks are mostly 
exceedingly irregular, with multitudes of sharp indentations, 
usually less than an inch deep, into which the feldspar has been 
filled. In many cases the plagioclase-rich filling sends off small 
tongues or dikelets, rarely over a foot long, ending in fairly sharp 
points in the anorthosite-gabbro. Some of the filled cracks are 
