24 NEW YORK STATE MUSEUM 



for industrial uses such as building stone or quicklime. Still it is 

 suitable for crushed stone and is used in considerable quantities for 

 road and railway ballast and concrete work. 



The upper portion of the limestone was formerly known as the 

 Seneca limestone and is characterized by great numbers of a small 

 brachiopod, C h o n e t e s 1 i n e a t u s. Many of these small shells 

 have a decided pink color. This portion of the limestone is gen- 

 erally free from chert but contains considerable clay disseminated 

 through the mass so that it crumbles rapidly on exposure to the 

 weather and hence has no economic use. 



The Corniferous portion of the limestone between the Seneca 

 and the crystalline, while it contains many trilobites and other fossils, 

 is much less productive of organic remains than the top and bottom 

 layers. 



MARCELLUS AND CARDIFF SHALES 



Overlying the Onondaga limestone is a great thickness of Devonic 

 shales that forms the higher hills and in fact the great plateau 

 of southern and south-central New York. Only a few hundred 

 feet of these shales occur on the Syracuse area. The overlying 

 higher ones appear as one goes southward over the higher portions 

 of the plateau. 



Immediately overlying the Onondaga limestone is a bed of ar- 

 gillaceous fissile shale about 275 feet thick. Formerly it was all 

 classed as the Marcellus shale but recently this term has been limited 

 to the lower part, about 100 feet in thickness, and the upper portion 

 is called the Cardiff shale. 



The contact between the Marcellus and the overlying Cardiff 

 shale is not sharply defined. The Marcellus is typically a black 

 bituminous shale with numerous iron carbonate concretions scattered 

 through certain portions of it, most abundant near the middle of 

 the bed. The carbonate concretions vary in size from a few inches 

 to several feet in diameter, sometimes nearly spherical in shape 

 and sometimes flattened or lenticular. Some of the concretions 

 have been shattered and the cracks filled in, forming typical septaria. 

 Calcite, siderite, and barite are the common minerals filling the 

 cracks in the septaria. In places the shale is twisted and distorted 

 around the concretion caused by pressure exerted by the growing 

 nodule. 



As indicated on the map, the Marcellus shale crops out over an 

 area about 4 miles in length across the southwestern corner of thej 

 Syracuse quadrangle. Good exposures of it may be found in the 



I 



