164 



NEW YORK STATE MUSEUM 



TYPES OF INLIERS OBSERVED IN NEW YORK 



BY RUDOLF RUEDEMANN 



The geology of the State of New York is so varied that it fur- 

 nishes striking examples of nearly a.11 important geologic phe- 

 nomena. It is the purpose of this paper to direct attention to the 

 illustrations found here of a group of such phenomena which 

 has hitherto not received the attention it deserves and has there- 

 fore been described in a rather loose terminology. These phe- 

 nomena are the inliers scattered throughout the State which have 

 been currently described or cited as " outliers." 



The direct occasion of this note has been the observation of a 

 peculiar group of detached outcrops observed by the writer while 

 engaged in mapping a portion of the Clayton sheet. These were 

 found to be of types (produced by corrasion and solution) not 

 mentioned in the textbooks. 



The term inlier originated in England about 50 years ago and 

 Page in his Handbook of Geologic Terms (1865) defines it thus 

 [p. 256] : " Inlier, a term introduced by Mr Drew, of the Geologi- 

 cal Survey, to express the converse o>f outlier. It means ... a 

 space occupied by one formation which is completely surrounded 

 by another that rests upon it." 



This original definition is retained in the Century Dictionary, 

 while Shaler, in the Standard Dictionary, defines inlier as "A 

 former outlier or uneroded portion of an older rock which, having 

 formed an island or an elevation during some later deposit, has 

 thus become embedded in a younger rock." This definition takes 

 notice of but one of many possible modes of production of inliers. 



If we wish to derive the definition by taking the converse of 

 the current one of an outlier [see Geikie, Earth Sculpture] as "A 

 detached mass of rock resting upon and surrounded on all sides 

 by older rocks" we obtain the following: A detached mass of 

 rock surrounded on all sides by younger rocks that rest upon the 

 unexposed portions of it. There exist, however, as we shall 

 presently see, but a few kinds of inliers that are detached masses, 

 while the great majority are continuous with the mother rock. A 

 definition which is to embrace all these classes must, therefore, be 

 given a wider scope and omit reference to the feature of detach- 

 ment. For this reason, the definition which we find in Scott's 



