THE GREENSANDS OF NEW JERSEY. 1 75 



and less with reference to the supposed similarity of faunas and 

 deposits with other and particularly European horizons. 



The difficulties in the way of extended correlation are so great 

 that for purposes of study it is often necessary to apply local 

 names to the several formations of a particular district. There 

 are, beyond a doubt, objections to the multiplication of names of 

 geological horizons and already accepted terms should be employed 

 as far as possible, but very frequently they prove to be inadequate 

 for stratigraphical requirements. Such is the case in the New 

 Jersey area. 



Outside of the major divisions of the geological column it is 

 impossible to employ the terms of European authors. All such 

 attempts have, upon critical examination, failed to stand the test. 

 The lithological and faunal characteristics show such wide varia- 

 tions that definite correlations of minor horizons are impossible. 

 The geological formations of America must be studied first upon 

 their own mei'lts and only after a complete understanding of them 

 has been gained can satisfactory comparisons be made with for- 

 eign areas. A detailed correlation of the New Jersey formations 

 with European will therefore not be attempted. 



Again the conditions under which the strata of the different 

 portions of this country were deposited, are so varied that the 

 same terms are not applicable over wide areas. The formations 

 of the Interior are in a marked degree dissimilar from those of 

 the Atlantic border, and even throughout the coastal plain very 

 considerable differences are found in its various portions. Cor- 

 relations of more satisfactory character can be made here than 

 with foreign areas, but many obstacles debar the geologist from 

 the full consummation of his task. It is possible to show in a 

 general way the equivalency of the deposits upon the Atlantic 

 border with those in the Gulf, the Interior, or on the Pacific coast, 

 although in the case of individual formations such comparisons 

 are of doubtful character. 



Dr. White ^ in his admirable essay upon the Cretaceous of 

 North America, discusses very critically the evidence for the 

 'Bull. U. S. Geol. Survey, 82, 189 1, 273 pp. 



