Geological and Mineralogical Notices. 231 
is engulphed in some fissures in the rock, and at a distance of two 
hundred yards issues again at the base of a small ledge and finds its 
way in an open and shorter current to Black river. The channel 
below this fissure is therefore perfectly dry. The rock in the wood 
‘ near by, is cavernous, as indicated by the subterraneous passage of 
the river—by several small accessible caverns, with roof and sides 
formed of large confusedly congregated masses, and by a rumbling 
noise when a carriage is driven over the road—the structure of this 
part indicating the effect of a powerful disruptive agency. 
In the dry bed of the stream the rock has a different aspect in seve- 
ral particulars from the superior strata as found in the cliffs—the fossils 
are madreporites, corallines, and orthocere, in great number, and the 
latter of large size imbedded and their upper half abraded by the cur- 
rent, but their septa, as usual, harder than their gangue, still project- 
ing above its surface. These are from two to three feet in length; the 
siphunculus filled with cale spar, and the whole in some cases mineral- 
ized, as it were, by a hard, black limestone, with a conchoidal fracture. 
All attempts to detach a complete specimen were futile, but my 
search was rewarded by finding loose the smaller termination of an 
orthocera, perfect in its external form—septa oblique to its axis— 
about eight inches long—diameters at the upper end five inches and 
three inches and a half—and circumference twelve inches and a half; 
and if the entire length were in proportion to these dimensions, com- 
pared with the specimens above cited, this one must have been many 
feet long. 
The strata here are much thicker than those in the upper series, 
and the bed of the stream in its whole width, and for a quarter of a 
mile, is divided at various distances apart, by several parallel longi- 
tudinal fissures, which are not vertical, but have a considerable dip 
to the east and a direction as nearly as I could judge without a nee- 
dle, N. by W. and S. by E. Obliquely these are intersected by 
other similar fissures—direction nearly N. E. and S. W., and dip 
S.E. nearly. The intersection of these, of course divides the rock 
into rhomboidal blocks, having a double inclination, whose sides are 
oblique angled parallelograms, and each opposite pair equal and 
similar. With two straight edged sticks, the only means at hand, I 
attempted, with the assistance of a friend, to measure the angles of 
intersection of the fissures, which were transferred carefully to paper 
with the pencil, viz. a. 672°, 6. 1113°=179°; c. 10739, d. 72°=— 
1794°, Allowing for error in measurement of half a degree, we 
have the following result—to a. and 6. and c. add half a degree, and 
