50 
RELATIONS OF THE TACONIC 
Whitehall mountain, so that all doubt in regard to its position and relation is removed by 
direct inspection. 
The diagram in Fig. 2 illustrates the position and relations exhibited at Whitehall. 
Fig. 2. 
a, a. Easterly prolongation of the mountain, which is surmounted by the Calciferous sandrock; b, b. Tertiary clay; 
c, c. Taconic and black slate ; d, d. Calciferous sandstone, unconformable to the Taconic slate, and dipping 
southeast at an angle of 40 - 45 degrees. 
From this exposition, no one can doubt the Avide difference in age between this slate and 
those of the Hudson river; the former being below the oldest members of the New-York 
system, while the latter rest conformably upon the middle members of the Champlain 
division. The Taconic or black slate, the newest member of the Taconic series, was not 
only deposited anterior to the other under consideration, but was disturbed or removed 
from the horizontal position; and its deposition and disturbance seem to mark the close of 
one geological period of great duration, if we may judge from the united thickness of the 
rocks belonging to it. 
Another section (Fig. 3), differing but little in detail from the preceding, but exhibiting 
more fully the relations of these systems, is annexed. 
Fig. 3. 
Near a church three miles east of Whitehall, is a deep ravine in which the Taconic slate, d, d, is denuded; 
a, a. Calciferous sandstone. 
Another section (Fig. 4), passing through the slates and shales of the Hudson river aa 
well as the Taconic slates, is taken from the hills of Greenbush opposite the city of Albany. 
Fig. 4. 
d 
a. Tertiary clay; b. Hudson river shales; c, c. Taconic slate; d. Calciferous sandstone. 
Passing east from the ferry, the first rocks are the shales of Hudson river, overlaid by tertiary 
clays: these continue to the Red mill. Leaving the mill, the rocks are concealed till Ave reach 
the summit of a Ioav range of hills bordering the eastern side of the valley of the Hudson. 
