104 
GEOLOGY 
by, or rather appears to cover a tongue of transition, which occupies progressively a diminishing width 
as far south as Dan river. 
This secondary formation is interrupted after it passes Frederickstown, but begins again between 
Monocasy and Seneca creeks, the north eastern boundary crossing the Potomac, by the west of Center- 
ville, touches the primitive near the Rappahannok, where it finishes. On the north west side it is 
bounded by the primitive, from some distance to the westward of Hartford, passing near Woodbury, 
and recommencing south of the Hudson, passing by Morristown, Germantown, etc. to the Delaware; 
after which it continues along the transition, by the east side of Reading, Grub’s mines, Middletown, 
Fairheld, to near the Potomac, and recommencing at Noland’s ferry, runs along the edge of the tran- 
sition to the westw'ard of Leesburg, Haymarket etc. to near the Rappahannock. 
All this secondary appears to be the oldest red sandstone formation , though in some places about 
Leesburg, Reading etc. the red sandstone only serves as cement to a pudding, formed of limestone of 
transition,’ and other transition rock pebbles, with some quartz pebbles. Large beds of greenstone trap 
and wacke of different kinds , cover in many places this sandstone formation , and form the small hills, 
or long ridges which occur so frequently in it. 
The stratification in most places runs from an east and west to a north east and south west course, 
and dips generally to the N. W. at an angle most frequently under 45 degrees from the horizon, co- 
vering both the primitive and transition formations , at every place where their junction could be exa- 
mined ; and in some places , such as the east side of the Hudson (where the action of the water had 
worn away the sandstone) the smooth water-worn primitive w’as covered with large rolled masses of 
greenstone trap to a considerable distance, the hardness and solidity of which had most probably sur- 
vived the destruction of their sandstone foundation ; may not similar derangements be one of the causes 
of the broken and unconnected state of this formation ? 
Prehnite and zeolite are found in the trap of this formation ; considerable deposits of magnetic iron 
ore at Grubb’s mines are enveloped, and have their circular layers intersected by greenstone trap , on 
a ridge of which this extensive cluster of iron ore appears to be placed. 
Grey copper ore has been found in the red sandstone formation near Hartford and Washington in 
Connecticut; at Scheuyler’s mines in Jersey, copper pyrites and native copper have been found. The me- 
tallic veins on Perkiomen creek, containing copper pyrites, blende, and galena, are in the same formation ; 
running nearly north and south , across the east and west direction of the red sandstone ; a small bed 
from an half to three inches thick of brown or tile copper ore is interspersed and follows the circular 
form of the iron beds at Grubb’s mines. 
Besides the sandstone formation, there is included within the described limits of the primitive, a bed 
of transition rocks, running nearly S. W. from the Delaware , to the Yadkin river, dipping generally to 
the south east 45 degrees or more from the horizon ; its width is from two to filteen miles , and runs 
from the west of Morrisville, to the east of Norristown, passes Lancaster, York, Hanover, Frederick- 
town. Bull run mountain, Milton, foot of Pig river, Martinsville, and finishes near Mount Pilot, between 
the Delaware and Rappahannock; it is partially covered by the red sandstone formation, and is in the 
shape of a long wedge, the thick end, touching the Delaware, and the sharp end, terminating at the 
Yadkin. 
This range consists of beds of blue, grey, red and white small grained transition limestone, alter- 
nating with beds of Grey wacke and Grey wacke-slate-, with granular quartzose rocks, and a great va- 
riety of transition rocks , not described or named in any treatise yet published ; much of this limestone 
is intimately mixed with Grey wacke-slate , other portions of it contain so great a quantity of small grai- 
ned sand, as to resemble Dolomite, and perhaps might with propriety be called the transition Dolomite, 
in many places veins and irregular masses of silex, variously coloured (mostly black) run through it, 
and considerable beds of fine grained white marble, fit lor the statuary, occur. 
