62 Cherty Lime-rock, or Corniferous Lime-rock. 



Erie. It abounds in hornstone and stone horns, (as the petrifac- 

 tion, Cyathophyllura, is called.) Seven distinct species are found 

 in this rock, at Bethlehem Caverns, in Albany county ; but the 

 Cyathophyllum ceratites is most abundant. As hornstone is found 

 in no other rock in the district, but the calciferous sand-rock, (a 

 good example of which is Flint Hill on Erie Canal,) its presence 

 (hornstone) is a good test of the identity of the stratum. This 

 rock being less subject to disintegration than the overlying gray 

 slate, it may be traced by its naked out-cropping edge, and more 

 or less of its flat surface, as follows. It forms the bottom of the 

 whole eastern part of Lake Erie ; Port Erie is on it, and its wall is 

 of blocks of this rock. Its north edge may be traced in an east- 

 erly direction, by way of Auburn, (the state prison there is built 

 of it, ) to Otsego county. Here it changes its course ; taking a 

 southeasterly direction to the south part of Albany county. Here 

 it exhibits its cavernous character, in the two caverns of Bethle- 

 hem ; and numerous other caverns are found in that vicinage. 

 From Bethlehem caverns it extends along the west side of Hud- 

 son River, through Esopus, (Kingston,) Esopus strand, and up the 

 Rondout. Then it gradually disappears under the very gray 

 slate, (third graywacke,) which embraces Carbondale coal beds, 

 &c. This statement I make from my own personal examina- 

 tions ; generally accompanied by my students in geology, from 

 time to time, through twelve successive years. 



Throughout the whole extent of this vast rock, as you follow 

 it from Lake Erie to Esopus strand, it is seen to pass laterally to 

 the right, under higher rocks. It manifestly forms the basis rock 

 of the Catskill and the Alleghany mountains ; and it is said to crop 

 out on the west of Alleghany. It was for these reasons that in all 

 my geological surveys, I used this rock as the line of reference 

 for other strata ; as strangers in New York City use Broadway 

 as a place of reference for other streets. I now advise the two 

 gentlemen referred to, (Messrs. Conrad and Rogers,) and other 

 state geologists, to take six points on this rock, and to proceed 

 from them in a transverse direction, over all the rocks above and 

 below it. The points I would assume, are — 1, Lake Erie ; 2, 

 Auburn ; 3, at Otsego ; 4, at Bethlehem caverns ; 5, at Catskill ; 

 6, the Rondout creek, on the Hudson and Delaware canal. 



As most of the geological surveys of the states, where such sur- 

 veys are undertaken, seem to agree in applying the nomenclature 



