103 
flow or the propagation of the metamorphic agent being thus 
governed. 
The concluding epoch of the whole era, was a cessation of 
subsidence, and the rising again of the whole intervening 
country, at least fifty miles wide, upon an anticlinal axis, thus 
draining the Lagoon, tilting the Lacustrine beds which formed 
the sloping walls of its basin into their present divergent 
dips, and bringing these slopes up into horizontal planes. 
Il. Lirgonocy AND MINERALOGY. 
The author expresses his surprise, that notwithstanding the 
immense use made of the rocks of this range, particularly in 
New York, for building, paving, etc., there has been so little 
ascertained with certainty, about their Mineralogical composi- 
tion and characters. He has himself extensive series of 
analyses in progress and projected, but pending their comple- 
tion, finds some most important points determinable by data 
already on record, with the addition of numerous density 
determinations he has made, and examinations of Mineralogi- 
cal characters. 
The rock of the Palisades is generally classed as a Diorite, 
and vaguely described as composed of “‘ Feldspar and Horn- 
blende.” Considerable search led to the finding, near the 
West End of the Erie Tunnel, of a ledge containing bunches 
of crystals coarsely enough aggregated for mechanical separa- 
tion. The dark cleavable prisms imbedded in a crystalline 
milky white paste, are plainly Orthorhombic, and therefore 
neither Hornblende nor Pyroxene. Their characters are 
clearly those of a ferrous Bronzite, or the species called by 
Dana, (5th Edition of Mineralogy,) Hypersthene, (a name 
heretofore obscurely applied to several species, including some 
Pyroxenes.) The frequent association of this with Labrado- 
rite, leads to the suspicion that the Feldspathic constituent is 
the latter species, and the rock a Hyperite instead of a Diorite. 
3 grams of it dissected out (of which an analysis will be 
made) gave density 2°626; that of the whole mass 
being 2-983 ; Von Waltershaugen gives for crystals of Labra- 
