102 
throughout its upper portions, to be bedded and laminated 
conformably with all the overlying rocks, the planes of 
lamination being composed of Magnesite. He therefore 
places this Serpentine at the basis of the Sub-Palisade beds, 
as an altered sedimentary rock. He connects the formation 
of this, with that of the Westchester Dolomites. Thus by 
interaction of water, Silica and Calcareous beds (of Zoic 
origin) in the metamorphism of the underlying Schists, at a 
high heat, produced probably by the enormous dynamic ten- 
sions in play, Silicates were formed, with concentrated aqueous 
solutions of Carbonic Acid. Such solutions would necessarily 
make their way towards the surface, and would meet at lower 
temperatures Magnesian and Caleareous Silicates. As well 
known, solutions of Bicarbonate of Magnesia would be 
formed to the exclusion of the Lime. Still nearer the surface, 
and at still lower heats, in permeating beds in the one case of 
Silicious (Opaline or Chalcedonic) materials, the interleaved 
Serpentine and Dolomite would be formed, and in the other 
case, Calcitic layers converted into Dolomites. In similar 
ways the metamorphic traps must have been formed, as well 
as the heavy beds of highly-laminated rocks which every- 
where underlie the Palisades, and which have been designated 
Trapoid Schists by the author. 
The frequent enclosure, in the coarser beds, of pebbles, of 
the shales and laminated sandstones themselves, as fully 
consolidated as their present matrix, which must have come 
from higher levels, shows that during the process of deposi- 
tion, a tilting must at times have been going on in a direction 
opposite to that which has since brought up the beds into 
their present positions, in order to bring up older beds of the 
Sandstones themselves, towards the N. W., that had been 
deposited long enough, to have already undergone concretion. 
Such tilting, however, need have been but comparatively 
small in amount, and was.a necessary consequence of a greater 
subsidence along the axis of the basin. Such slight inward 
inclination of the beds on both sides of the basin, explains 
the crescent form of the edges of the sheets of trap. The 
