254 DR. THOMAS STERRY HUNT ON THE 
wacke. More recently, it has been, by Prof. Cook, in his geological survey of New Jersey, 
described as belonging to a still lower horizon, and, under the name of Potsdam, referred 
to the base of the Primal of Rogers. -The lithological characters of this belt, as I have observ- 
ed it in New Jersey, are however like those of the First Graywacke, as seen in Pennsyl- 
vania, and east of the Hudson, and unlike the Primal. This, in the adjacent region of 
northeastern Pennsylvania, along the same gneissic belt is, where it appears from beneath 
the Auroral, represented only by a small volume of quartzite, with soft schists ; 
a development very unlike the Green-Pond Mountain conglomerate. I am therefore 
disposed to regard this latter, with Emmons, as a portion of the First Graywacke or Upper 
Taconic, lying outside of the great valley, on the gneiss of the South Mountain range ; 
while in the valley itself it rests upon the Lower Taconic. 
§ 99. The relations of this Graywacke belt to the Auroral limestones often found 
adjacent, as well as to other and fossiliferous limestones and shales, met with along the 
range, both in New Jersey, and in Orange county, New York, are complicated by many 
stratigraphical accidents, and demand further investigation. A summary of the facts 
regarding it, as gathered from the reports of Mather and of Horton, is given in the author’s 
Azoic Rocks, pages 35 to 37 ; while, for later observations by Prof. Cook, in New Jersey, the 
reader is referred to his volume in the geology of that state, published in 1868, already cited 
in§80. In Bearfort Mountain, in this region, according to Cook, the conglomerate beds are 
overlaid by slates, which are followed by sandstones, called Oneida and Medina, the Au- 
roral limestone being unrepresented ; while at Upper Longwood, fossiliferous limestone, 
regarded as Trenton, overlies the red slates of the conglomerate belt (loc. cit. pp. 149, 83): 
An area of fossiliferous argillites, found in the Peach-Bottom district in Lancaster 
county, Pennsylvania, some distance to the south-east of the second Taconian belt, and on 
the Susquehanna River, along the borders of Maryland, is probably to be regarded as 
an outlier belonging to the First Graywacke ; since it has lately furnished to Dr. Frazer, 
eraptolites referred by Prof. Hall to that horizon. Iam indebted to Dr. Frazer for these 
facts, the results of Prof. Hall’s observations not being as yet published. 
§ 100. Passing now to the consideration of the Upper Tacconic rocks in the regions north 
of the Highlands of the Hudson, where they have been chiefly studied, we remark, in the 
first place, that here, as farther south, they are found resting alike upon the Lower Taconic, 
and the older crystalline rocks which appear on the western border of the latter.. The base 
of the Upper Taconic, as described by Emmons, here consists of coarse greenish sandstones, 
with shales and conglomerates, holding materials derived from the underlying crystalline 
rocks. The higher part of the series was said to be very variable in character, including olive- 
coloured sandstones, and so-called brown-weathering calcareous sandstones, which are really 
arenaceous dolomites holding mnch carbonate of iron ; beds of quartzite with green, purple 
red roofing-slates, followed by blue limestones,—the Sparry Lime-rock of Eaton ; while 
towards the summit are black shaly limestones, the series terminating with a black slate. 
The upper part of this series was declared to be fossiliferous, containing remains of 
graptolites, fucoids and trilobites. 
In a section from near Comstock’s Landing, eastward to Middle Granyille, in 
Washington county, New York, in which the above described rocks are found, there is, 
Emmons tells us, no representative of the granular quartzites, the limestones, the talcose 
slates, or the characteristic roofing-slates of the Lower Taconic. The rocks in this section 

