Limestone Belts of Westchester County, N. Y. 205 
columnar (basaltic) structure; because the fractures to be 
filled in such cases are fractures in rocks which are participat- 
ing in the movement and which, therefore, are heated rocks, 
and not — 
gal the phenomena of contact and the facts as to inclu- 
sions, structure and superpositions may have distinctive pecul- 
ie 
. The condition of fusion or plasticity in the Cortland region.— 
To. answer the question before us we have, therefore, to pre 
sider more closely than has been done the phenom ena of co 
tact of the schistose with the massive rocks over the: Cortland 
region, the peculiarities of some of the eerie fat the charac- 
teristics of some of the so-called veins or dikes the charac- 
ters of the rocks as to their transitions, iaaciian and rela- 
tive positions. 
3. Special facts from the Cortland region. 
Contact-phenomena between the schistose and massive rocks ; 
Fras connected with the inclusions ; stratigraphical relations to the 
limestones. —The facts with reference to inclusions and all contact- 
phenomena bear directly, as will appear, upon the question as to 
any stratigraphical relation ‘in the Cortland rocks to the lime- 
stones ; and they are, therefore, here taken from the vicinity 
of particular limestone areas. 
fi 1) The vicinity of Cruger’s limestone area.—The small lime- 
Stone area near Cruger’ st ine map), lies mostly to the south and 
el portion about forty feet in 
greatest width borders the river west of it, beyond the first 
brick-yard (1), the rest of the westward extension of the lime- 
stone being beneath the river. The schistose rocks directly 
and conformably adjoin it on the north, the average strike of 
both being N. 70° K. and the dip 75° to the northward. In 
the aT nae portion of the area there is a twist in the 
whole to the northwest. The limestone is finely crystalline 
granular, mostly white in color, and over the hills to the east- 
ward contains crystals of white pyroxen 
The schist north of the limestone ey a thickness of about a 
thousand feet. Toward the limestone, it is a silvery mica schist 
containing a little black mica and an abundance of very small 
garnets undred yards or so to the north it is staurolitic, 
the staurolite occurring in grains of a clear chestnut- brown 
color and rarely in distinct er ystals ; and it also in some parts 
heopmnen quartzose and consequently thick-bedded. There are, 
seams containing much magnetite ; and at one place an 
intercalation of a black sas rock containing hese feldspar 
which is about equally orthoclase and a soda-lime species. 
After another hundred to a hundred and fifty yards north- 
