The name Newton Hamilton formation is here applied to the widespread shaly facies of the Onondaga group in central Pennsylvania. The formation is divisible into two members: the Hares Valley dark gray shale and limestone member, above, a new name; and the Beaverdam Run dark gray shale, below, a name modified from the usage of Willard.

The bituminous materials of the Devonian shales in the Mt. Union area range from .002 to .24 per cent of the rock, with the Marcellus black shale containing the largest quantities. The bitumens, on separation by means of column chromatography, were found to contain fractions referable to saturated hydrocarbons, aromatic hydrocarbons, asphaltenes, and polar compounds.

Experiments with gas chromatography of the bituminous materials suggest that most of the column chromatographic fractions consist of compounds having carbon numbers above 20.

Upward from the Ridgeley sandstone to the Newton Hamilton, Marcellus, Mahantango, and Burket shales, the saturated hydrocarbons form an increasing percentage of the bitumens and of total hydrocarbons whereas the aromatic hydrocarbons decrease upward. This relation is believed to have a paleogeographic significance, resulting from the greater stagnation and poorer circulation of the Oriskany through Marcellus seas as compared with the Mahantango and Burket.

A resume is given of some of the relations of the bitumens to the petrologic-environmental types (petrai); the nearshore petra and depressional sapropelic petra are relatively more favorable for hydrocarbon preservation than some of the other types.

Free sulphur is found in many of the Newton Hamilton and Marcellus samples but is less common in the overlying Mahantango. The sulphur-bearing layers, also characterized by increased content of aromatic and tarry fractions, imply restricted poorly circulated seas under stillstand or regressive conditions during deposition of the Onondaga and Marcellus.

Separation of a humic acid constituent having absorptive peaks at 264-272 mµ was made by sulphuric acid hydrolysis and paper chromatography. This material, believed to be a pyridine compound, ranges from .04 to 2 per cent of the Devonian rocks, with the greatest concentrations occurring in the Marcellus and Burket black shales.