106 
GEOLOGY 
The general nature of metallic repositories in this formation appears to be in beds, disseminated 
or lying in masses : when in beds (as the magnetic iron ore , and black lead) or disseminated as the iron 
pyrites, octahedral iron ore , Molybdena etc. they occur at intervals through the whole range of the forma- 
tion; veins to any great extent have not yet been found in this formation. 
TRANSITlOxX FORMATION. 
This extensive field of transition rocks, is limited on the S. E. side from a little to the eastward of 
lake Champlain , to near tbe river Alabama , by the N. W. boundary prescribed to the primitive rocks ; 
on the N. W. side it touches the S. E. edge of the great secondary formations, in a line, that passes 
considerably to the westward of the dividing ridge, in Georgia, North Carolina, and part of Virginia, 
and runs near it in the northern part of that State, and to the eastward of it in the States of Pennsyl- 
vania and New-York. 
This lino of demarkation runs between the Alabama and Tombigby rivers, to the westward of the 
north fork of the Holstein river, until it joins the Alleghany mountains near the sulphur springs, along 
that dividing ridge to Bedford county in Pennsylvania, and from thence N. E. to the east side of the 
Catskill mountains on Hudson’s river. This lino of separation of the transition and secondary formations, 
is not so regularly and distinctly traced as in the other formations, many large valleys are formed of 
horizontal secondary limestone, full of shells, while the ridges on each side consists of transition rocks, 
etc. the two formations interlock, and are mixed in many places, so as to require much time and at- 
tention to reduce them to their regular and proper limits. It is however probable, that to the N. W. 
of the line here described, little or no transition will be found, although to the S. E. of it, partial for- 
mations of secondary may occur. 
The breadth of this transition formation is generally from 20 to 40 miles , and the stratification runs 
from a north and south to a north east and southwest direction, dipping generally to the N. W. at an angle in 
most places, under 45 degrees from the horizon. On the edge of the primitive; it, in some places, deviates from 
this general rule , and dips for a short distance to the south east. The most elevated ground is on the 
confines of North Carolina, and Georgia, along the S. E. limits to Maggotty Gap, descending towards 
the N. W. until it meets the secondary ; from Magotty Gap ; north easterly, the highest ground is on the 
north west side, sloping gradually tow'ards the primitive, which ranges along its south east boundary. 
The outline of the mountains of this formation, is almost a straight line, with few interruptions, 
bounding long parallel ridges of nearly the same height, declining gently towards the side, where the 
stratification dips from the horizon, and more precipitous on the opposite side, where the edge of the 
strata comes to the surface. 
This formation is composed of a small-grained transition limestone, of all the shades of colour from 
white to dark blue, and in some places it is red, intimately mixed with grains of grey wacke slate, also 
of lime spar in veins , and disseminated ; siliceous flinty veins and irregular masses, in many places there 
is an intimate mixture of small sand , so as to put on the appearance of dolomite, this is in beds from 
50 to 5000 feet in width; it alternates with grey wacke, and grey wacke slate, a siliceous aggregate, ha- 
ving particles of a light blue colour, from the size of a pin head to that of an egg, disseminated, in 
some places in a cement of a slaty texture, and in others in a quartz cement ; a fine sandstone cemen- 
ted with quartz in large masses, often of a slaty structure, with small detached scales of mica inter- 
vening, and a groat variety of other rocks, not described or named by any author, which from their 
composition and situation cannot be classed but with the transition. 
The limestone, grey wacke, and grey wacke slate, generally occupy thevallies; the quartzose aggre- 
gates, the ridges ; amongst which is that called the millstone grit; this must not bo confounded with 
another rock, likewise denominated the millstone grit , which is a small grained granite, with much quartz, 
found in the primitive formation ; there are many and extensive caves in the limestone of this forma- 
tion , where the bones of many animals are found, as well as the remains of marine insects and shells. 
