1887] ‘Thè Taconic Question Restated. 247 
rocks hitherto called Hudson River group, Hall admitted the 
distinctness and the greater antiquity of these. In 1877, while 
justifying the retention of the name of Hudson River group for 
the fossiliferous rocks of Loraine age found along the banks of | 
that river, and originally called “Hudson slates” by Mather,— 
_ which Hall speaks of as “the newer series, or the rocks above 
the Trenton limestone,” as contradistinguished from the older or 
infra-Trenton series,—he admits that “the error lay in extending 
the term [Hudson River group] to rocks on the eastward, at a 
time when their fossil contents had not been studied . . . and 
their geological position had not been determined by critical ex- 
amination.”’* 
The geological position of these rocks to the eastward and 
their relation to the newer series had, however, already been de- 
- termined, and Hall, in 1862, did but repeat the statements long 
before made by Emmons, who, in 1842, had declared that the 
Taconic slate group was undoubtedly overlapped along its west- 
ern border by “the Loraine or Hudson River slates.” Again, 
in describing, in 1846, beds of the Loraine shale alternating with 
the sandstone of the Gray band in the valley of the Rondout, and 
in their northern outcrop along the termination of the Helder- 
berg range, Emmons declares that this section of the Loraine 
strata “resembles the beds which occur in patches on the east 
side of the Hudson along the Western [Boston and Albany] 
Railway. These latter beds may be clearly distinguished from 
the slates and shales of the Taconic system. They neither con- 
form with them in dip nor in strike,” and, except in the immediate 
vicinity of the great northern fracture of the Hudson valley, their 
dip and their disturbance are not excessive. These unconform- 
ably overlying areas of Loraine shales resting on the older Gray- 
wacke were said to form a small range between Chatham Centre 
and Chatham Four Corners, “ where they lie in deep troughs and 
are exposed in the railway cuttings.” In some cases, we are told, 
“their peculiar distribution and the confined limits of the fossilif- 
erous beds’ render quite difficult the recognition of these shales 
when they lie in proximity to the Taconic system.”? It was thus 
clearly shown by Emmons, in 1844, that the Loraine shales not 
mely overlie the Upper Taconic or First Graywacke along its 
t Proc. Amer. Assoc. Adv. Science, 1877, p. 263. 
2 Emmons, —— of New York, pp. 124, 125, 128. 
