148 Classes of Rocks. 



pile of books. We. see the same between Niagara Falls and 

 Levviston, one hundred miles west. At Black Rock we see 

 the geodiferous rock pass under the cornitiferous. This latter 

 we see pass under the pyritiferous at the same place ; and 

 this continued along the south shore of lake Erie, also by way 

 of Ithaca to Catskill mountains. 



Thus we demonstrate by actual inspection, the true order 

 of superposition. Nothing is left for conjecture or hypothesis. 



On pursuing the lateral extension of strata, we arrive at 

 certainty in regard to several important localities. We have 

 traced the cornitiferous limerock of Black Rock at lake Erie 

 to Bethlehem caverns, in Albany county, and thence through 

 Greene into Ulster county. We find that all the most ele- 

 vated part of Catskill and Allegany mountains is the third 

 graywacke of the south shore of lake Erie. Also that 

 the old red sandstone of Werner is not a general stratum. 

 It often forms extensive beds in the third graywacke, and is 

 also found in the second graywacke in some places. Cony- 

 beare seems to favor the opinion that old red sandstone is 

 not a general stratum. I think our district furnishes ample 

 evidence of its being merely in beds. The red sandstone of 

 Connecticut river and under the palisadoes of the Hudson, 

 is certainly the saliferous rock of Conybeare ; and the con- 

 glomerate is his breccia. See introduction to Phillips and 

 Conybeare, p. 15. 



As the proposed nomenclature depends entirely upon facts 

 for its support, I shall make particular reference to those lo- 

 calities which are most accessible to stage lines, packets, 

 and places of public resort. With this brief view I shall 

 close that part which is expressly devoted to nomenclature. 

 But I shall make numerous applications to this subject when 

 I treat of facts which belong more exclusively to the second 

 part of the canal survey. 



CLASSES OF ROCKS.* 



I. Primitive Rocks. 



1 . Granite. 



At West Point we find as extensive layers of crystalline 

 granite, as at any place which I have visited. Here it always 



* These localities were all searched out and examined'under the direction and 

 at the expense of the Hon. Stephen Van Rensselaer, during the last seven years. 



