S. W. Ford—Age of Rocks near Schodack Landing. 207 
In addition to the above, I have also obtained from this band 
the ae graptolitic forms figured on plate B of Decade II of 
the Geological Survey of Canada (1865), figs. 15 and 18. In 
view of it the evidence, I think there can be no doubt that 
these slates are the exact renee of the Graptolite-bearing 
beds of the Norman’s Kill, near Albany. Stipes of the G. 
 eegie have been obtained has over a foot in length, and 
all of the species occur in a remarkably perfect state of preser- 
vation 
The eee s Kill slates were assigned by the New York 
‘Geological Survey to the horizon of the Hudson River group ; 
and although doubts were subsequently raised by the investi- 
gations of the Canadian geologists as to the correctness of this 
reference, I became satisfied in 1871 and 1872, after an ex- 
caution appeared to me necessary in pronouncing upon the age 
of beds characterized by simply one or more of these species of 
graptolites, and not demonstrably their eebater Nice: equiva- 
lents, in other places. For instance: in the sum of 1870, I 
obtained specimens of Graptolithus pristis, @. eaters and a 
third species which I was unable to determine, from the slates 
immediately east of the Hudson River at Troy; and later I 
found good specimens of the first mentioned species in the 
folded slates between Troy and Lansingburgh, along the line 
vate i Schodack Landing, I at once resolved to institute 
a careful search for other fossils in the rocks of the neighbor- 
hood; and before quitting the field, my researches were re- 
smith shop, at Schodack village, there is a bed of limestone, 
about two feet thick, and, in part, somewlrat brecciated in 
appearance, enclosed in the slates; and about a quarter of a 
mile from the river, in the bottom of a deep gorge running 
eastward along the Columbia County line, the same limestone 
band, mae situated, is again met with. From the mode of 
The same or a acm band, abounding in the same species, occurs about a 
mile duis “ef Castl , On an east-and-west road connectin Syith: the the regular 
highway from Pace ser Landing to that village. It strikes obliquely across the 
eee only a few rods from the latter, or just beyond the residence of 
