DEVONIAN. 293 



The strata comprised in this interval are described as gray calcareous shale, 

 gray limestone composed of remains of encrinites, and soft shales. There are also 

 black shales which may indicate the passage from the Marcellus to the Hamilton. 

 Logan cites several partial sections, and BrummeP"^ gives well records which 

 include the Hamilton. 



Under the name "Portage and Chemung group" Logan ^^ cites the occurrence 

 of black bituminous shales, which may represent the Genesee and which occupy a 

 small area at Kettle Point, on Lake Huron. He says: 



Here, in a low cliff, on the west side of the cape, is a section of between 12 and 14 feet of 

 very fissile black bituminous shales, weathering to a leaden-gray, and often stained brown by 

 oxide of iron. A yellow earthy coating of oxalate of iron is sometimes found in the surfaces of 

 the shales, which also contain nodules and crystals of iron pyrites, besides pecuHar spheroidal 

 concretions, whose fancied resemblance to inverted kettles has probably given its name to the 

 point. They vary in size from 3 inches to as many feet in diameter, and are sometimes nearly 

 spherical and at others somewhat flattened, generally on the under side. Occasionally a smaller 

 spheroidal mass is implanted on the top of a larger one. These concretions are readily broken 

 and are then seen to be composed of brown crystalhne carbonate of lime, which is confusedly 

 aggregated in the center and sometimes contains blende. Around this are arranged slender 

 prismatic crystals, which extend from the nucleus to the circumference, the whole having a 

 radiated columnar structure, which, not less than the terminations of the prisms at the surface 

 of the spheroidal masses, gives them very much the aspect of fossil corals. 



On the east side of the point the upper beds of the section are concealed, but the lower ones 

 come from beneath the bank at a Httle above the water's level and cover an area of several 

 acres, the whole surface being studded with these spheroidal concretions, which remain when 

 the softer shale around them has been partially worn away. 



This black shale is fossihferous and contains a fucoid resembling a variety of the Fucoides 

 mudchgalU of Vanuxem, which is very abundant in the lower beds. Flattened stems of Cala- 

 mites inomatus (Dawson), which are sometimes 7 or 8 feet long, and 3 inches wide, occur 

 about the middle of the section and are occasionally converted into coal. Besides these, accord- 

 ing to Dr. Dawson, there occurs here a stem which belongs to Sagenaria veltheimiana (Goeppert). 

 An undetermined Lingula is found with these plants, together with numbers of what appear 

 to be microscopic orbicular shells. 



The fauna of the Oriskany of Ontario has been carefully studied by Schuchert,^'" 

 and that of the Hamilton by Whiteaves.°^^'°^' Shimer and Grabau™ have pub- 

 lished measurements of local sections at Thedford, Ontario, and lists of fossils from 

 the several divisions, together with a discussion of correlation and faunal migration. 



K 17-18. PENNSYLVANIA AND NEW JERSEY. 



The Devonian formations of New York can be traced southward into Pennsyl- 

 vania and New Jersey, as was shown by Williams ^^° in 1884, by the work of the 

 respective State surveys, and by recent studies of several observers. Some of these 

 formations, however, notably the TuUy limestone, are exceptionally limited and are 

 not known to occur south or west of northeastern P3nnsylvania and northern New 

 Jersey. The Ithaca fauna, which is lacking in western New York, extends across 

 Pennsylvania in a belt that passes southeast of Altoona. The contemporaneous 

 fauna of the Portage of western New York occurs at Altoona, the two faunas being 

 inshore and offshore, as brought out by Williams and Kindle. ^^ 



