VEINLETS IN THE SILURIAN AND DEVONIAN 57 
cerning the mechanics of vein formation than is to be found in the 
larger and more complex ones. It was for this reason that the 
present investigation was undertaken. 
Many small veins are present in the Silurian and Devonian 
formations of central New York. ‘These rocks are well exposed 
in the numerous limestone and gypsum quarries of Cayuga and 
Onondaga counties. In the summer of 1916 the writer visited all 
of the quarries now being worked in these counties and nearly all 
of those that are idle, but most of the data used in this paper were 
obtained in the extensive quarries found in the vicinity of Union 
Springs. 
STRATIGRAPHIC FEATURES 
The rock formations outcropping in the region studied are listed 
below: 
Devonian 
Skaneateles shale 
Cardiff shale 
Marcellus shale 
Onondaga limestone 
Oriskany sandstone and conglomerate 
Silurian 
Manlius limestone 
~Roundout limestone 
Cobleskill limestone 
Bertie waterlime 
Camillus shale 
(Syracuse salt) 
Vernon shale ) 
Salina formation 
Rock salt in the form of lens-shaped beds is present at many 
places immediately below the Camillus shale, but it has been re- 
moved in solution wherever the covering is less than about 1,000 
feet thick, and therefore is never found near the outcrops of the 
strata." 
The Camillus shale contains intercalated beds of impure mag- 
nesian limestone and of gypsum. The limestone layers are more 
abundant in the upper part of the shale and probably represent 
* D. H. Newland and Henry Leighton, “‘Gypsum Deposits of New York,” N.Y. 
State Museum Bull. 143, 1910, p. 21. 
