492 HISTORICAL GEOLOGY. 



Oneida County, N.Y., where the limestone stands in bold bluffs along the 

 wild cafion of West Canada Creek, and affords a good place for the study of 

 the rock and its fossils. 



1 . Trenton Epoch. — In the region of Trenton Falls the limestone is a 

 blackish to dark gray thin-bedded rock, OAving its color, like the Utica shale, 

 to carbonaceous or bituminous material. The lower part of the Trenton 

 formation is called the Black River limestone, from Black Eiver ; it outcrops 

 to the north of Trenton Falls, and, like the Trenton, it is widely distri- 

 buted over the country. A stratum, 30 feet or less thick, at the bottom of 

 this limestone in central New York, is the Birdseye limestone — a gray, dove- 

 colored rock, speckled with white crystalline points, that are due in part at 

 least to the presence of a fossil coral and its crystallization into calcite. 

 The Kentucky Chazy limestone contains similar " birdseyes," and has great 

 thickness. The Trenton in Wisconsin, Illinois, and Iowa is a bluish gray to 

 buff-colored rock. Above it lies the " Galena limestone," about 250 feet thick, 

 mostly dolomyte, which is noted for its deposits of lead ore ; it corresponds 

 to the later part of the Trenton epoch. 



2. Utica and Hudson Epochs. — The shales of the Utica epoch outcrop 

 along a narrow region in the MohaAvk valley, east and west of Utica, the 

 place after which they are named; and those of the later Hudson epoch, 

 along the south side of the Utica shales. They also extend down the Hudson 

 River valley (whence the name) to Fishkill ; but part of the shales formerly 

 called Hudson River shales have proved to be Cambrian. 



The Hudson shales have their greatest thickness in eastern New York. 

 A boring 15 miles west of Albany passed through 3440 feet of shales, partly 

 the Utica shales, into the Trenton limestone. In central New York, 20 miles 

 west of Oneida Lake, a boring went through 1000 feet of Hudson and Utica 

 shales, and at Utica, through 800 feet of the two. The impure limestone and 

 shales of the region about Cincinnati are of the Hudson epoch. The thick- 

 ness at Cincinnati is about 750 feet. The lower part of the series contains 

 fossils of the Utica shale of New York, mingled with other species belonging 

 to the Trenton or the Hudson rocks of New York. In Ohi6 and Kentucky 

 the Cincinnati beds overlie 600 or 700 feet of limestones and shales which 

 are mainly of the Trenton epoch. 



1. Canadian Period. 



1. Calciferous Epoch. 



a. Eastern Border region. — In noi thwestern Newfoundland, on the Straits of Belle 

 Isle, Upper Calciferous is stated to include 2061' of limestone. Below these are the Lower 

 Calciferous of the age of the New York beds (Billings, Logan). The beds continue down 

 the coast of Newfoundland to Bonne Bay and beyond. The Calciferous is 250' thick at 

 the Mingan Islands, and continues from there to St. Genevieve, on the Lower St. Lawrence. 



h. Appalachian and Interior Continental regions. — In some places in New York the 

 layers of the Calciferous are hard and siliceous, and contain geodes of quartz crystals, as 

 at Diamond Rock, Lake George, and at Middleville and elsewhere in Herkimer County, 



