J. D. Dana—Hornblendice and Augitie Rock. 385 
Stony Point on the opposite shore of the Hudson. I showed, 
by the occurrence of dikes in the limestone of Vetplahok:s and 
other peculiarities, that they were once in fusion or a plastic 
state; but I suggested that 5 fusion may have been connected 
with the metamorphic action that crystallized the rocks of the 
region, and that the peculiar constitution of the rocks may 
have come from previous igneous ejections a tufaceous 
deposits. 
Since the publication of my paper, a north-and-south cut has 
een made through the rocks of Stony Point for the “ West 
Shore” railroad, and it is now clear that these rocks are of true 
eruptive origin. The line of the railroad extends southward 
in succession, the “ soda cones the Eda ee rock and the 
mica schist. The exposed section of the chrysolitic rock (which 
is mainly chrysolitic hornblendyte) is about 250 yards lo One: Tn 
the section it appears to constitute a dike about N. 60° E. or S. 
0° W. in course; but the map shows that the mass exte nds at 
the surface hardly a hundred yards west of the railroad, the 
mica schist apie: the surface rock beyond this distance. 
he mica schist (a gneissoid mica schist) exposed to view in 
the tailvond cut south of the igneous mass becomes vibes 
flexed as it nears the dike; but this increase of flexure in its 
beds has nothing to do with the eruption of the homblendyte, 
while it has some connection with the origin of the soda-gran- 
ite, as shown near Cruger’s on the east side of the beste 
The south wall of the dike or erupted mass, or the plane 
of contact with the mica schist, has a strike of about N. 55° 
K., and dips 80° to the northward. Some effects of the heat 
from the melted rock appear in the schists, and among them 
there are in a few places greenish spots or nodules. 
he north wall of the chrysolitie hornblendyte mass is not 
well exposed to view but appears to be nearly vertical. Against 
it there i is, first, for about thirty-five feet, /imestone which is in 
rh a very coarse limestone-breccia having the igneous rock 
as its cement, but in places shows nearly vertical bedding, par- 
allel nearly to its junction with the next rock nortb, the soda- 
granite. This breccia contains large angular masses of lime- 
Stone, and resembles the limestone breccia of Verplanck Point 
(described on pages 201 and 202 of volume xx of this Journal, 
September, 1880), in its appearance, its cement and the very 
small effect of heat at the contacts with the cement beyond 
some mutual impregnations. The limestone at Verplanck 
* The seale of the hime is 800 feet to the inch. 
+ The “rock” I have since named hemidioryte, the name often used in lithology, 
micadioryte, be Relesaity 
