MARCELLUS SHALES, 147 



•but generally interrapted flattened masses, with interposed slate or shale ; the masses pre- 

 -senting curved surfaces, showing that the cause of the coming together of their particles was 

 the same with that which produces septaria, the character of which they often assume as to 

 •external form, and also as to the cracks or internal divisions, or septa, from whence the name 

 of septaria was derived. The whole of the layers and septaria, and shale, was a deposit of 

 argillaceous and calcareoas mud in variable proportions. Where the calcareous material was 

 abundant, it produced layers; where but in small quantity, it separated into globuliform 

 masses or septaria. 



The upper shales are not so highly colored as the lower ones. Near Marcellus, and in 

 other parts of Onondaga where best observed, they show no fossils for one or two hundred or 

 more feet where thickest. They are disposed to separate, when long exposed, into small thin 

 edged fragments, the result of a peculiar accretionary structure ; the fragments often exhibit- 

 ing stains in spots from iron rust, and also minute crystals of gypsum, the effect of the action 

 •of decomposed pyrites and limestone particles. The upper mass appears to diminish in thick- 

 ness east and west from Marcellus, 



There are but few fossils found in this rock, but most of these are peculiar to it ; among 

 them is 



No. 1 of the wood-cut, the Expanded goniatite, the whorl enlarging rapidly towards the mouth. 



No. 2. The Marcellus goniatite. This species is more abundant, and some are of great size. 

 A fragment of one was found, which, when perfect, must have been nearly a foot in 

 diameter. Both specimens are in the State Collection. The goniatites were found only 

 in the two upper limestone layers of the lower shales, and in several points between 

 Oneida creek and Marcellus village. Were the rock broken or quarried, numerous 

 specimens might be found of this fossil. A segment is given, merely to show the diffe- 

 rence between the two species. 



No. 3, is the Limitary orthis. It is very abundant in some localities, and appears to be 

 coextensive with the shales and the lower part only of the Hamilton group, and to be 

 in greater number near the junction of the two, from whence its name. It is exceedingly 

 rare where the mass is thick ; not having been noticed near Marcellus, where the mass 

 is at its maximum. 



No. 4. Marcellus cypricardite (cast). 



There are several other fossils : For example, an avicula, which resembles a posidonia ; 

 a large orthocera, the Marcellus, which is about a foot in diameter, and is associated with the 

 goniatites ; also a more slender one in the shale, but the characters obscure ; a lingula, and 

 several small shells not yet investigated. 



Some portions of the lower shales are black and friable from small carbonaceous fucoids or 

 graptolites, the forms too imperfect to determine without minute and patient examination. 

 From such bodies obviously the seductive particles of carbon were derived, which made this 

 mass so great and general an object of search for coal throughout its long east and west range 

 through the State. 



