NEW YORK STATE MUSEUM 



two systems of parallel faults that both hade in the same direction 

 (southeast). It might therefore be considered to be more of the 

 character of an overthrust wedge [see below] than of the 

 horst, in which, when typically developed, the faults incline away 

 from each other. It is, however, apparent that in the general 

 sense of a horst, as now understood in Europe, as a fault block, 

 that is on the upthrow side with reference to all the area around 

 it [see text fig. 29], the Highlands fulfill all conditions of this type 

 of structure. 



c Branching fault inliers. A 

 small division of raised blocks, 

 appearing as inliers is formed by 

 branching faults, where a triangu- 

 lar block remains standing between 

 the branches. The Mohawk val- 

 FlG . 29 a horst (after Haug) le >' finishes again a few good 



examples of this group [see text 

 fig. 25] of inliers, that are mostly recognized by their sub- 

 triangular outline. Below St Johnsville we find a. triangular out- 

 lier of Beekmantown with a surrounding band of Trenton emerg- 

 ing from the Utica shale, and the Noses fault (below Sprakers) 

 with its branch, the Ephratah branch fault, forms another triang.- 

 ular Beekmantown inlier. 



d Wedge inliers. As wedge inliers or " wedges " we designate 

 here inliers that are found between two overthrusts. There is no 

 doubt that many such wedges exist in our eastern, much over- 

 thrust slate belt, but the close isoclinal folding of the belt ob- 

 scures the faulted structure there to such an extent, that it is 

 preferable to select typical examples from less disturbed areas. 

 The Appalachians furnish many clear cases of this structure, of 

 which we select, on account of the great difference in age of the 

 adjoining rocks, one from the Briceville folio, Tenn. [Geol. Atlas 

 of the United States, 1896]. It will be seen in the section [see 

 text fig. 30] that five overthrust faults are there recognizable be- 

 tween them containing three wedges of Siluric rocks, which on the 

 surface form narrow, bandlike inliers in Carboniferous rocks, 

 sometimes flanked by a narrow strip of Devonic rocks. 



e Overthrust inliers. We designate as overthrust inliers those 

 which result from the extensive transportation of older rocks over 

 younger owes along more or less horizontal thrust planes, resulting 

 from overturned anticlines (" fold thrusts " of Willis) and from 



