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180 Association of American Geologisis and Nakanntiaie: 
Prof. H. Be Rovers presented some details in relasiaie to the 
striated surfaces of the northeastern counties of Pennsylvania, 
and the adjacent districts of New York, proving that while the 
seratehes which abound on the summits of all the mountain 
ridges in that part of the Appalachian chain observe a nearly 
north and south direction, answering to their prevailing course 
throughout New England and the country of the lakes, those on 
the sides and’ bottoms of the valleys, obey with remarkable 
fidelity all the local deflections which a body of moving waters 
would encounter among the ridges and valleys of this entangled 
range. In the neighborhood of the Wyoming valley, the sum- 
mits of the mountains, elevated about two thousand feet above 
the sea, and one thousand five hundred above the valley, are 
covered with nearly parallel strie, pointing a little west of south, 
but on their slopes, in the bed of the valley, these lines fol- 
low other directions conforming to the course which any ob- 
structed inundation would pursue. Thus, near Wilkesbarre, 
the northern flank of the southern mountain, which was here ex- 
posed to the full brant of the inundation, exhibits’ the “grooves 
with a direction compounded of the general meridional one, and 
that of the deflecting mountain wall. High on the side of the 
ridge, the striz ascend the slope obliquely, but nearer the base 
they are parallel to the medial axes of the valley. Near the la- 
teral notch, in the northern mountain at Nanticoke, they point 
toward the gorge, showing that a portion of the current here 
came from a quarter south of east. A great northern wave 
would, so long as it submersed in its first impetuous rush the 
siminits of the mountains, move forward regardless of the local 
inequalities of the surface, but after it had partially subsided, the 
long parallel ridges would present so many barriers to divide and 
locally deflect the now feeble remnant of the drainage. Review= . 
- ing the phenomena which he has observed, Prof. Rogers con- 
_ cludes that the strize were produced by the friction of the over- 
lying ‘Stratum of drift itself, urged into rapid motion from the 
é one or more sudden’ inundations. From the absence 
near the ‘southern border of the striated region of granitic, oF 
other fat transported northern bowlders, he inférs that floating 
om the north, has had no ageney in fartowing atid 
the snrfgces ofthe strata, "(i SHY piiwese Ae 
