Geology of the Country near Easton, Penn. 237 
ore are found in various parts of this range; the rock is 
distinctly stratified, and the strata nearly vertical. 
Serpentine—under this generic term may be classed a 
formation of talcose slate and steatite, which accompanies 
the sienite of Chesnut Hill. It occurs on the south-east 
side, varies from one to three hundred feet in width, and 
contains a great variety of minerals. 
Transition Limestone abounds in the vicinity of Easton. 
It has a bluish gray colour; splintery fracture ; and con- 
tains veins of hornstone. Hitherto it has not been found to 
contain any fossil remains. Its strata are inclined at differ- 
ent angles, from 10° to 80°, and are sometimes curved. 
Caverns abound in this formation; an interesting one may 
be seen at Durham, about nine miles from Easton, and in 
many places this rock presents isolated summits of the 
most picturesque form. Every part of its surfaee is distin- 
guished by the fertility of the soil. 
Transition Granite—the most singular feature in the 
geology of Easton is a rock of granite which appears to re- 
pose on the transition limestone. Itis found at Mount Par- 
nassus, about four hundred yards south of the Delaware 
bridge, in the State of New-Jersey. This granite is well 
characterized, consisting of quartz, feldspar and mica, and 
is inclined at an angle of 70°. Diluvial debris surround it 
on every side, and thus its exact junction with the limestone 
cannot be perceived ; but it has the same inclination as that 
rock, and contains a vein of limestone. 
Transition Clay Slate extends from the foot of the Blue 
Mountains, nearly half way across the valley: there is a 
marked difference between the fertility of the farms situa- 
ted on this tract, and those of the transition limestone. 
Slate quarries have been opened on this formation near 
the banks of the De aware, by a company of proprietors in 
Philadelphia; but the inferiority of the transition slate has 
rendered the shares not very productive. 
Transition Sandstone—this name may be applied toa 
quartzose breccia, of which the Blue Mountains are com- 
posed in this part of their range. They may be distin- 
guished at a great distance by the shadowy tint of the for- 
ests by which they are covered, and by the eyen line with 
which they bound the horizon. Where the Lehigh rive: 
passes through the mountain, the breccia exhibits polygo- - 
