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TACONIC QUESTION IN GEOLOGY. 237 
this opening is a slope with a still steeper dip to the northwest, on what appears to be 
the same ore-bed ; indicating the presence of an anticlinal in the ore-bearing strata. At 
Boyerstown, still further east, where the mesozoic lies along the south-east flank of the 
South Mountain, there is opened, at its margin, a mine in which the ore-stratum had, in 
1875, been followed down the slope, 400 feet, at an angle of forty-five degrees to the east 
of south. At the great Cornwall mine which, like all those above mentioned, lies on 
the northern border of the mesozoic, the ore-bearing strata are very slightly inclined ; 
while at the Jones mine, on the southern border, they have a general inclination to the 
northward, and pass visibly beneath the adjacent mesozoic sandstone. 
§ 51. The identity of mineralogical characters in all of the localities mentioned is 
very marked. The association with the granular magnetite, of pyrites, with portions of 
copper and cobalt, the admixture of a greenish granular silicate, apparently related to 
pyroxene, and the constant proximity to the ores, of limestone and serpentine, leaves no 
doubt that we have to do with one and the same stratigraphical horizon ; which, as the 
observations in many of the localities show, is unconformably subjacent to the contiguous 
mesozoic rocks. It may here be noted that the concretionary structure of some of the 
limestone-masses which accompauy the ore-beds in these Primal slates, has led to their 
being confounded with the conglomerate of limestone-pebbles, often found in the mesozoic 
strata of the region. 
All of the rocks which, in the southeastern area of Pennsylvania, (that is to say, to the 
southeast of the Kittatinny Mountain), belong to the Primal or Auroral divisions of Rogers ; 
as well as those portions of the Matinal which are not included in the First Gray wacke, or in 
the small Ordovician areas (f 31, 34) appertain to the Lower Taconic series of Emmons. 
IV.—Lower Taconic Rocks IN VARIOUS REGIONS. 
§ 52. The Lower Taconic rocks, as seen in their typical locality, the Taconic Hills in 
Williamstown and Adams, Berkshire county, Massachusetts, were described by Emmons as 
including, at the base, a conglomerate of varying thickness, resting upon the ancient gneissic 
rocks of the region, from the ruins of which it is derived ; and consisting of pebbles and 
fragments of quartz and feldspathic rock in a so-called talcose paste. Above this is found a 
rock described as a quartziferous talcose schist, sometimes including needles of tourmaline, 
and followed by the characteristic Granular Quartz-rock of Haton. This, like the similar 
rock in Pennsylvania, has afforded Scolithus linearis; a specimen from Adams being figured, 
together with one from Chikis, Pennsylvania, by Hall, in his Paleontology of New York, 
vol. i. pl. 1.* Above this Scolithus-sandstone, which is 100 feet thick, is a succession of 
talcose slates, with two interposed beds of quartzite, one of which, fine-grained, massive and 
jointed, measures 400 feet in thickness ; the whole succession appearing in Oak Hill, arranged 
in a synclinal form, with moderate dips, and having a thickness of about 1,200 feet. 
§ 53. Immediately succeeding this, is found the Stockbridge limestone or marble, often 

* These two specimens, and a similar one, the locality of which is not given, are the only ores figured by Prof. 
Hall as the Scolithus of the Potsdam. This form however is not known in the true Potsdam sandstone, as seen in 
the Champlain and Ottawa basins; nor, so far as I am aware, on the upper Mississippi; through all of which 
regions this sandstone is characterized by the very distinct form described by Billings as Scolithus Canadensis, 
See Azoic Rocks, pages 135-139. . 
