. DEN ER De 
238 DR. THOMAS STERRY HUNT ON THE 
dolomitic, and having its bedding-planes in many places marked by scales of a greenish 
micaceous mineral, called tale by Emmons ; the presence of which gives rise to varieties of 
marble resembling the Italian cipollino. The limestone is white or gray in colour, some- 
times very dark, and more rarely reddish. To this mass, as seen on the western slope of 
Saddle Mountain, a thickness of 500 feet was assigned. Succeeding this is a mass of 2,000 
feet of soft slates, resembling those found below the limestone, and also occasionally inter- 
stratified with it. The limestone is said to be, in fact, intercalated in a great series of such 
slates, and to appear in similar relations throughout western New England and eastern 
New York. The aggregate thickness of the whole series in Berkshire county, as above 
described, was estimated by Emmons at about 3,700 feet. 
§ 54. The roofing-slates of the series are, according to him, included in the great mass 
of so-called talcose slates above the Stockbridge limestone, and are found, with similar 
characters, from Massachusetts to North Carolina. Elsewhere, he mentions that a band of 
argillites of variable thickness, adapted for roofing-slates, is also sometimes found in the 
schists beneath the limestone. Emmons was careful to distinguish between these Lower 
Taconic argillites, and those red and green roofing-slates which are found in the Upper 
Taconic. He farther affirms that the talcose slates, with their associated roofing-slates, are 
not found in the Upper Taconic series. 
§ 55. It is well known that throughout this belt of Lower Taconic rocks east of the 
Hudson, as well as farther south, great deposits of limonite are found in the decayed 
schists of the series. Associated with this is an aggregate described by Emmons as an 
iron-breccia, made of fragments of quartz cemented by limonite, which, according to him, is 
characteristic of this horizon in Vermont, Massachusetts, Pennsylvania, Virginia, North 
Carolina, and Tennessee. Such a quartziferous limonite is also described by C. U. Shepard 
as found in the same belt at Kent in Connecticut. * In an iron-mine, open in 1875, near 
Reading, Penn., I examined a similar aggregate, holding numerous pebbles of white 
quartz in a paste of limonite. At a depth of sixty feet, the ore-stratum being highly 
inclined, the limonite was replaced by granular pyrites, also holding quartz-pebbles, and it 
was evident that the alteration of this bed of pyrites had given rise to the limonite-con- 
glomerate. 
§ 56. The Lower Taconic series, according to Emmons, is as well developed in the 
southern as in the northern United States. “From the northern part of New England 
it is prolonged southward, and upon the line of prolongation it continues uninterruptedly 
for more than one thousand miles.” It extends, in fact, through the whole length of the 
great Appalachian valley, and is well known from Pennsylvania south-westward through 
Virginia and East Tennessee to Georgia and Alabama. A section of these rocks 
from near Wytheville, in the valley of Virginia, and another near Harper’s Ferry, will be 
found described by Emmons in his American Geology, part II. These resemble closely both 
that of Berkshire county, Massachusetts, and those in Pennsylvania given in the pre- 
ceding chapter. With all these, we may compare a recent section along the western base 
of the Blue Ridge, in Virginia, described in a private communication from Prof. W. M. 
Fontaine. The granular quartz-rock with Scolithus, here 300 feet thick, is separated from 
the great mass of limestones above by about 600 feet of slates with limonite, and is under- 


* Geological Survey of Connecticut, 1837, p. 23- 
. 

