20 THE GEOLOGIST'S TRAVELING HAND -BOOK. 



grits of the Hudson River that can scarcely be distinguished from these. The Utica 

 slate weathers ash-gray, rapidly disintegrates, and, where it is exposed in cliffs, 

 frost and other agents constantly break it into small fragments, which collect at 

 the base in the form of a talus. In Pennsylvania, it outcrops, with little or no 

 variation, as a dark blue carbonaceous slate and shale, extremely fissile in its lower 

 beds. It forms the surface-rock along a narrow region in the Mohawk Valley. 

 In East Tennessee, the beds both of Utica and Hudson River, or Cincinnati, are of 

 great extent, and consist of blue calcareous and sandy shales, with some layers of 

 calcareous sandstone. Professor Hall considers the Utica slate as properly the 

 lower member of the Hudson River group. 



4 c. Hudson River, (Cincinnati, Nashville, Loraine and Frankfort sandstone 

 and shale.) The rocks of this group in New York are mostly slates, shales 

 and gray, slaty and thick-bedded grits. The slates and shales are generally 

 dark brown, blue and black, and the grits are gray, greenish and bluish-gray. 

 They are stratified and conformable, alternating a great number of times, without 

 any regular order of alternation, and in Eastern New York are from 500 to 800 feet 

 thick. The first New York geologists called this formation the Greywacke, and 

 it is still so called by the stone-cutters on the River Hudson. Its lower portion was 

 called the Frankfort slate and sandstone, and the upper part the Pulaski shale and 

 sandstone, which latter were afterwards called the Loraine shale. Wherever streams 

 have passed over it they have, in process of time, worn hi the rocks a deep channel 

 or gorge, sometimes preventing a free communication across them, as at Loraine, 

 (See note No 69, New York.) By decomposition, it produces a tenacious, clayey 

 soil, favorable for grass, forming the best dairy-land, as in Orange Co., New York, 

 about Goshen and Middletown. It increases in thickness southward so rapidly 

 that at the Delaware and Lehigh water-gaps, measurements of 5,000 feet have 

 been made through it, from its top downwards, without reaching its lower limit. 



In many places along its last outcrop towards the Atlantic, it has furnished 

 many masses of a substance resembling anthracite, also beds of impure limestone, 

 and beds of red shale, which increase very much going south into Virginia. 



In Pennsylvania, the Hudson River slate consists of blue and greenish-gray 

 shale, alternating with gray calcareous and argillaceous sandstone in thin beds. 

 The sandstones grow more abundant as we ascend in the formation. The middle 

 portion, where much metamorphosed and intersected by cleavage-planes, in certain 

 localities, produces a good roofing-slate, as at Slatington and Delaware Water 

 Gap, Pa. 



The geologists of the western states generally, have dropped the designation 

 of Hudson-River, at least hi regard to strata west of the Alleghanies, and have 

 substituted for it the name, CINCINNATI, proposed by Worthen and Meek ; making 

 this term co-extensive with the former. In this guide, Hudson-River is used in 

 the Eastern and Cincinnati in the Western States. At Cincinnati the whole series is 

 about 800 feet thick, and, according to Dr. Newberry, by its fossils, is the equivalent 

 of the Chazy, Trenton, Utica and Hudson-River, all blended together. In Ohio it 

 is composed of alternating beds of limestone and shale, the latter sometimes 

 called blue clay. The limestone is an even-bedded, firm, durable, semi-crystalline 

 limestone, crowded with fossils. It is commonly called the blue limestone, but the 

 prevailing color is grayish-blue, and the weathered surfaces show yellowish or 

 light gray shades. In Southern Illinois the lower part of the Cincinnati is 

 composed of brown sandy shales and sandstone, and the upper portion is a thin- 



