:l.J STEW YORK. 251 
77 7./. J" LIMESTONE. 
DISTRIBUTION. 
The thinness of the Tally limestone would probably allow it to be 
lisregarded as a Portland-cement material if it were not for its advan- 
tageous distribution. It occurs only in central New York, and occu- 
pies a greater area than any other limestone in that part of the State. 
Its line of outcrop, moreover, crosses all the Finger lakes, on the shores 
If most of which the limestone is we.ll exposed, and the belt is crossed 
my numerous railroad lines leading to the coal regions of Pennsyl- 
vania. With these advantages of position, even a relatively thin 
|imestone bed is worth considering, and one Portland-cement plant 
hat uses the Tully limestone is already in operation. 
The most western known exposure of the Tully limestone is near 
leed Corners, Ontario County. From this point it runs southeastward 
hrough or near Gorham, Stanley, Hall Corners, and Dresden, disap- 
)earing below the waters of Seneca Lake opposite the village of 
jtarkey. It reappears on the east shore of the lake about 5 miles 
outh of Willard, and is exposed almost continuously along the lake 
ihore as far north as Willard. Here it turns eastward through Hayt 
Corners, then southeastward near Sheldrake to the Cayuga Lake shore 
>ast of Covert, and thence southward along the west shore through 
rrumansburg to Glenwood. Its most available outcrops are, however, 
>n the east shore of Cayuga Lake, which it follows closely from 
Portland Point north to opposite Kings Ferry. Turning northeast- 
vard the limestone outcrop leaves the lake and passes through Poplar 
lidge, Sherwood, and Scipio. From this point to its most eastern 
tnown outcrop, which is near Smyrna, Chenango County, the outcrop 
)f the Tully limestone is too irregular for ready description, as can be 
seen from the map, PL X, opposite page 246. It is sufficient here to 
indicate its course by saying that the principal villages and stations 
on or near the outcrop are, in order eastward, Cascade, Locke, 
Moravia, Miles, Glenhaven, Scott, Spofford, Borodino, Otisco Valley, 
Tully, Truxton, Cuyler, Deruyter, Georgetown, and Smyrna. 
COMPOSITION. 
The Tully limestone is low in magnesia, rarely carrying over 1^ per 
cent of magnesium carbonate. It commonly carries a rather large 
percentage of silica, alumina, and iron oxide, at times approximating 
in composition the Lehigh Cement rock. The analyses given on page 
252 are fairly representative of its range in composition. 
The limestone is immediately underlain by a series of shales which, 
as shown by the experience of the Portland-cement plant near Ithaca, 
are well adapted to mixing with the limestone. 
