32 TRANSACTIONS OF THE [1888 



The study of both these formations is much hindered by the 

 bold reliefs of surface which arise throughout most of the region. 

 Steep hills have been cut out of a moderately inclined slope, 

 across the strike of which deep rivers have dug their way 

 abruptly through thick bodies of strata. At right angles to 

 these latter, creeks and branches of various kinds penetrate 

 deep into the adjacent land, and form at frequent intervals an 

 almost impassable barrier in the foul bogs which fill the depres- 

 sions on their borders. Next these, on the lowest slopes of the 

 hills, almost impenetrable thickets of bushes, vines and green- 

 briar cover the surface and conceal the mire that rests only a 

 few feet lower down. Between these drains, the hills rise in 

 cliffs and present the best exposures of the beds and strata. A 

 full section, however, cannot be obtained by referring only to 

 the steep bank rising from the river's ])rink. Ascending to 

 the top of such an exposure, an abrupt incline appears a few 

 feet or rods farther back, and upon examining this, often a third 

 stage of elevation is seen rising high above this second base of 

 erosion. The first section of such an exposure usually displays 

 the component beds and strata in their actual form, but the 

 next stage of ascent is apt to be covered by the loose materials 

 of its own upper portion, or to be partly concealed by the 

 shifting sands carried from the summits of the hills higher up. 

 Thus the Eocene sands often cover most of the slope of an 

 upper terrace, settle down upon the movable elements of the 

 next stage below, and form the red mantle which disguises the 

 hills as they are viewed from the surrounding country. 



