34 Geological Reports on the^tate of New York. 



Calcareous tufa is extremely common in these counties, as are 

 immense series of water limestones. 



Lime is very abundant in this region, and will supply to its 

 agriculture that indispensable ingredient of a fertile soil without 

 which cultivation cannot be permanent. The rocks of this dis- 

 trict are gneiss at the bottom, much water-worn ; caldferous rock, 

 reposing unconformably on the gneiss but much posterior in geo- 

 logical age, many rocks formed elsewhere between, being absent 

 here. 



Bird^s-eye limestone^ its beauty being due to the vertical stems 

 of the Fucoides demisus. Trenton limestone, its fossils are very 

 numerous ; in this are found the well known trilobites, Calymene, 

 Isotelus, &c. Black shale forms the floor through which the 

 other rocks have been thrust j abounds in fucoides, &c. ; contains 

 no fragment of other rocks. Green shale and its sandstones. 

 The upper layers abound with fossils, as Pterinea carinata, modi- 

 olario, pholadio, Productus planulata, &c. &c. 



Millstone grit, formed of pebbles of glossy quartz ; water- worn. 

 Protean group, two hundred feet thick ; shales and sandstones of 

 many colors, abound in fucoides, Crustacea, &c. Red shale, no 

 fossils. Water lime, no fossils ; drab color ; thin layers. This 

 rock, with the limestones above it, has furnished all the calcare- 

 ous tufa of Oneida and Herkimer. Upper limestone forms the 

 elevated plain south of the Mohawk; has many fossils, and 

 among them are trilobites. White sandstone. 



Pyritiferous rock. — This rock is remarkably subservient to 

 man's primary physical wants in agriculture and building, and to 

 his intellectual in geological science, while there is little incentive 

 to mining. 



It is probable that these formations have arisen from similar 

 causes with their supposed European equivalents, soon to be illus- 

 trated by Mr. Murchison's great work on Wales. 



Fourth District, comprising eleven or twelve cou?ities lyi?ig on 

 Lake Erie, southern shore, east of Niagara, west of Cayuga, 

 and north of the southern tier of counties ; by James Hall. 



This district was principally surveyed by Mr. Conrad and Mr. 

 Vanuxem ; but some notices may be added respecting its scien- 

 tific and economical geology. 



