166 



SCIENCE. 



|Voi.. ir., No. 27. 



Bangor, where it forms a series of hiimmocky bills, 

 which, a hundred to two lumdred feet in height, 

 and covered with transported and striated bowlders, 

 rise abruptly out of a clayey plain to the west. 

 Glacial striae upon exposed surfaces near Bangor 

 point south-west, or towards the moraine. After fol- 

 lowing the moraine to the base of the Kittatinny 

 Mountain, it became of great interest to know 

 whether a great lobe of ice descended from New 

 Jersey along the lower side of the mountain, or 

 whether a tongue projected through the Delaware 

 Water-Gap, or whether the glacier, even so close to 

 its southern limit, came bodily over the top of the 

 mountain, unchecked by it, and unchanged in its 

 course. The last, the most improbable of these 

 hypotheses, and certainly tlie least expected by the 

 author, proved to be undoubtedly the true one. The 

 author had been able to show that the moraine 

 crossed the mountain near Offset Knob; that large 

 bowlders, derived from lower elevations several miles 

 northward, lie perched all along the summit, fourteen 

 hundred feet above the sea; and that, as shown by 

 tlie numerous striae on the northern slope of the 

 mountain, running up-hill, the glacier moved diago- 

 nally up and across the mountain, uninfluenced in 

 any way by tlie pi-esence of the Water-Gap, and finally 

 carae to an end in the valley south of the moun- 

 tain, as marked out by the terminal moraine. Huge 

 bowlders of fossiliferous limestone, sometimes thirty 

 feet long, were torn by the ice from their parent 

 strata in Monroe county, on the north side of the 

 mountain, lifted up a thousand feet, carried across 

 the mountain, and dropped finally in the slate valley 

 of Northampton county. The author had found one 

 of these limestone bowlders upon the very summit of 

 the mountain, where the jagged sandstone rocks had 

 combed it out of the ice during its passage across. 

 The journeys of these bowlders were short; but that 

 of a well-rounded bowlder of Adirondack syenite, 

 which the author had found in the same county, was 

 about two hundred miles. 



Another interesting point is in Monroe county, 

 upon the summit of Pocono Mountain, over two 

 thousand feet above the sea, where a great ridge 

 of moraine hills twelve miles long, one mile wide, 

 and a hundred or more feet high, composed of 

 unstratified till, and bearing numerous bowlders 

 of Adirondack gneisses and granites, rises out of 

 the level, sandy plain of the Pocono plateau, and 

 sweeps around from Pocono Knob into Carbon 

 comity. Known locally as ' Long Ridge,' its origin 

 had never before been suspected. It encloses re- 

 markable little 'moraine lakes' without inlet or 

 outlet, and is heaped up into just such conical 

 hills as may be seen in the moraine in southern 

 Massachusetts. Nothing can more clearly show the 

 continuity and uniformity of action of the great 

 glacier than the identity of its moraine accumulations 

 at such remote points. 



In fact, the course of the moraine, as it winds from 

 the top of the Kittatinny Mountain down to Cherry 

 valley, and then up again on to the Pocono, is a 

 complete vindication of the glacial hypothesis. It is 



in no sense a water-level, nor could it have been 

 formed by floating ice. No other cause than that of 

 a great glacier could form a continuous accumulation 

 of glaciated material which contains no evidences 

 of water-action, and which follows such a course. 

 Neither on the mountains nor in the valley does the 

 moraine rest against any defined barrier, as would 

 be the case were it a shore-line. 



The kames of Cherry valley, fine examples of 

 wliich appear south of Stroudsburg, are interesting 

 relics of sub-glacial water-action. They are com- 

 posed of stratified water-worn gravel, having often 

 an anticlinal structure, and as a series of conical 

 hills and reticulated ridges, enclosing ' kettle-holes,' 

 form conspicuous objects in the centre of the valley. 

 They appear to have been formed by sub-glacial 

 rivers, which, flowing from the moraine backwards, 

 under or at the edge of the ice, emptied into the 

 Delaware valley. They thus probably differ in origin 

 from the longer kames in New England, and other 

 regions more remote from the edge of the glacier. 



The glacier had produced very slight effect upon 

 the topography of Pennsylvania. It neither levelled 

 down mountains nor scooped out caQons. The 

 glacier passed bodily across the sharp edge of the 

 Kittatinny Mountain without having any appreciable 

 effect upon it, the glaciated part of the ridge being as 

 high and as sharp as that part south of the moraine. 



In describing the course of the moraine across 

 Luzerne county, the author showed that it crossed 

 several mountain chains in succession, by each of 

 which it was locally deflected northward. At the 

 j)oint where the terminal moraine crosses Buck 

 Mountain, in a line diagonally across the mountain, 

 the moraine was so sharply defined that he was 

 able to stand with one foot upon the glaciated and 

 the other upon the non-glaciated region. It was 

 interesting to find, that infront of a mountain chain, 

 such as Huntington Mountain or the Alleghany 

 Mountain, the moraine was poorly developed, as 

 though the mountain had 'combed out' the drift 

 from the ice. 



He described an instructive portion of the moraine, 

 where, three and one-half miles north-west of Ber- 

 wick, it seems to abut against a high slate hill, which 

 furnishes, therefore, a section of the end of the 

 glacier. It shows that the extreme edge of the ice 

 was here only about four hundred feet thick, and 

 that, while the moraine and the scratched pebbles 

 were carried along at the base of the ice, sharp frag- 

 ments of sandstone were carried on top. 



In speaking of the apex made by the moraine in 

 New York, and of the high plateau region of Potter 

 county, it was inferred, from the local influence al- 

 ready shown by the author to have been exerted by 

 single mountain chains, that this region of liigh 

 elevation had a decided influence upon the general 

 course of the moraine. 



Certain facts observed as to the gravel-ridges of the 

 Allegheny River rendered it probable that the river 

 flowed under a tongue of the glacier, ten miles broad 

 and two miles long, through a sub-glacial channel, at 

 the time of its greatest extension near Olean. He 



