62 TRANSACTIONS OF THE [ FEB. l, 
sylvania, Poughkeepsie and Boston, and is eight miles south of the 
New York State line. The dike is two miles from the small town 
of Beemerville, which is the nearest place of any importance. It 
is fourteen miles northwest of Franklin Furnace, where the famous 
zine mines are located.. The general valley of ‘the Walkill River 
extends from Deckertown westward, and is ‘chiefly formed of Hud- 
son River shales or slate, which, according to Mr. Darton’s later in- 
vestigations, should be called in part Trenton.! Under these, east 
of Deckertown, is a blue limestone, and overlying them uncon- 
formably on the west is the Kittatinny conglome1 rate, which forms 
the ridge of that name and corresponds to the Oneida ‘conglomerate 
of New York. The dike comes out along the contact of the con- 
glomerate and the slate. They have been spoken of as unconform- 
able in the New Jersey Report for 1868, but this is a mistake. 
=<. FEZ f ee ee ee 
Co ee Se OOO 
SEG TIONG A 
The ridge, as shown on the map (which is an enlarged portion of 
the New Jersey topographical map sheet No. 1), forms a steep hill- 
side some six hundred feet above the neighboring valley. No stream 
of any size runs down its sides across “the syenite, and only small 
gulches afford exposures. The dike forms a ereat terrace, and is, 
in its broadest part, 300-400 yards across. Its outcrop is marked 
by a lineal succession of conical hillocks, with small gullies between, 
making rough topography. A depression runs along the western 
edge of the dike, and is somewhat wet. This marshy land effectually 
conceals the western contact. On the north the dike runs out as an 
easterly spur on the ridge. Evidences of its baking action on the 
shales run further, but no eruptive rock appears. It terminates 
with a steep hillside covered by loose fragments. At the southern 
extremity the eruptive rock appears along the Brick House Road, 
which crosses the mountain, but beyond the road it cannot extend 
far, as a great precipitous cliff of conglomerate called Decker’s Rocks 
comes in and diagonally cuts off its course. No outcrops appear 
at the foot of the ‘cliff, and the float material is all baked shale and 
sandstone. 
The dike varies considerably along its course. The typical 
elaeolite-syenite forms the northern third and the southern extremity, 
but between these points its character changes. Near the northern 
1N. H. Darton. A. J.-S., ili, xxx, 452, and xxxi, 209. 
