UPLIFTS, DISLOCATIONS, etc. 
295 
141 . 
Uplift in the strata, two miles above Eighteen-mile creek. 
CHAPTER VIII. 
Uplifts, Dislocations and Undulations of the Strata in the Fourth District. 
Situated as the western part of New-York is, mostly remote from any known rocks of 
igneous or hypogene origin, there are, as we should naturally infer, but few of those dis¬ 
turbances which manifest themselves along the margin of mountain ranges, or the vicinity of 
intruded rocks. Those which do present themselves are of little comparative importance, 
except as illustrating the extent of this force, which, in other places, has produced phenomena 
of the most stupendous kind. 
The existence of trap dykes upon the immediate borders of the district, show that the 
dynamics of igneous agency have not entirely slumbered. The undulations which extend, 
like immense waves, over the whole breadth of the district, show also the influence of some 
subterranean agency which converted the rocks into a billowy sea. 
The manifestations of local disturbance, whether from deep seated causes or from some 
local operation, are confined to a few slight upliftings or dislocations of the strata; sometimes 
an abrupt flexure marks the point of the application of force, where the strata have not been 
broken. The figure at the head of the chapter represents a slight uplift of the strata at the 
upper part of the Hamilton group. The thin mass, which is the encrinal limestone below the 
Moscow shale, together with this rock, is abruptly elevated about four feet. The limestone 
has been broken suddenly off, while the shale, though less sharply broken, is, nevertheless, 
