5 
The following paper was read :— 
On the Fossils found in the “ Flag-stones” used in the Cities of 
New York and Brooklyn. 
By Dr. R. P. STEVENS. 
The “ blue-stone” flaggings of our streets may be regarded 
as the perfection of sidewalk stones. or evenness of wear, 
as well as durability, they surpass all other materials used, 
unless perhaps the sandstones of the Highlands and of north- 
ern New York. 
These flags appear to consist of somewhat varying layers 
of sediments, chiefly fine-grained sands, with silicious, cal- 
careous, or silico-caleareous cements. The marks of ripples, 
rain-drops, and cross-wave action, which they exhibit, show 
them to have been littoral or mud-bank deposits. 
When closely examined, the evidence on this point is con- 
clusive. We find all the phenomena of sea-shore action 
which we see on the beach of the modern ocean. Where 
thin films of deposition, which form the surface of the best 
class of flags, are worn away, there may be seen little ridges 
of coarse sand and pebbles, such as are familiarly produced 
by the sorting action of tidal waves. 
Some of these ridges consist of pebbles of black flint, sug- 
gesting their source to have been among the cherty lime- 
stones of the Upper Helderberg group. 
All the fossil remains of these flags appear, moreover, to 
have been stranded waifs upon a shore. 
According to Prof. Dana, the rocks lying back of Kingston, 
N. Y., where these flags are quarried, belong to the Hamilton 
group. Similar flags in the south-western counties of the 
state, and along the Delaware River, I have been disposed to 
refer to the Chemung and Portage epochs. ‘The slabs are of 
great beauty and durability ; I have seen them full forty feet 
square, and have obtained specimens of good strength not a 
quarter of an inch thick, and literally filled with impressions 
of organic remains, chiefly cavities once occupied by joints 
of encrinal columns. 
Here Lam brought to the subject of the Organic Remains 
found in the flag-stones used in New York and vicinity. 
It may be worth while to remark, that specimens are most 
readily found either by inspecting the flags of newly-opened 
and out-of-the-way streets, where the rougher and poorer 
qualities of stone are employed, or by examining the reverse 
sides of slabs in the “ blue-stone”’ yards. 
