164 



SCIENCE. 



I Vol. II., No. 27. 



rock-exposures, the unstratified deposit of till, the 

 many kames, and especially the numerous glacier- 

 scratched fragments and pebbles, — all these deposits 

 are in strong contrast with those south of the moraine, 

 where all the gravels are stratified and the pebbles 

 water-worn, where the rocks are never polished or 

 striated, but, on the other hand, often decomposed 

 to a great depth, and where, except near the seacoast, 

 wide stretches of the more elevated regions are per- 

 fectly free from all drift. 



The method employed in discovering the line of 

 the moraine was to zigzag along its course from the 

 glaciated into the non-glaciated region, and vice versa, 

 going each time far enough on the one side to be fully 

 satisfied of the absence of glaciation, and, on the 

 other, to find undoubted traces of its action. 



Nowhere south of the line of the terminal moraine 

 had he found any traces of glacial action, all state- 

 ments by other geologists to the contrary notwithstand- 

 ing. When tyjiically developed, the terminal moraine 

 is characterized by peculiar contours of its own. A 

 series of hummocks, or low conical hills, alternate 

 with short straight ridges, and enclose shallow basin- 

 shaped depressions, which, like inverted hummocks 

 in shape, are known as kettle-holes. Large bowlders 

 are scattered over the surface; and the unstratified 

 till which composes the deposit is filled with glacier- 

 scratched bowlders and fragments of all sizes and 

 shapes. The average width of the moraine is about 

 one mile. 



At many places, however, the limit of glaciation is 

 marked merely by an unusual collection of large 

 transported bowlders. This is especially the case in 

 front of a high mountain range which has ' combed 

 out ' the drift from the ice. 



The general course of the moraine across Pennsyl- 

 vania was defined as follows: appearing first in 

 Northampton county, a mile below Belvidere, at lati- 

 tude 40° 49', it winds in a great curve, first westward 

 and then northward, reaching the base of the Kitta- 

 tinny Mountain, three miles east of the Wind-Gap. 



Ascending to the top of the Kittatinny Mountain, 

 sixteen hundred feet high, the moraine crosses the 

 great valley between the Kittatinny and the Pocono, 

 and then swings sharply back and around Pocono 

 Knob, immediately afterwards to ascend the steep 

 face of the mountain to the wide plateau on top, 

 twenty-one hundred feet above the sea. Crossing 

 this in a fine curve, and heaped up in an immense 

 accumulation, it goes first north and afterwards west, 

 reaching the gorge of the Lehigh Eiver, some ten 

 miles north of Mauch Chunk. It crosses the gorge 

 at Hickory Run, and, without swerving from its 

 general north-western course, ascends mountain 

 range after mountain range, descends to the valley 

 of the east branch of the Susquehanna, and crosses 

 the river at Beach Haven. 



Then, following the base of Huntington or Knob 

 Mountain, it finally ascends it, and crossing its sum- 

 mit, at a height of fifteen hundred feet above the 

 Susquehanna just below, descends the north slope of 

 the mountain to the broad, undulating valley to the 

 north. Taking a northerly course, it follows up on 



the east bank of Fishing Creek to the North or 

 Alleghany Mountain, enters Lycoming county, 'passes 

 westward along the base of the mountain, crossing 

 in its course the Muncy and Loyalsock creeks, and 

 then, near the village of Loyalsock, turns at right 

 angles, and ascends the mountain. 



Having reached the summit of the AUeghanies, 

 over two thousand feet above the sea, it passes west 

 through a wild, wooded region nearly as far as [Pine 

 Creek, where it begins a nearly straight north- 

 westward course through the south-west corner of 

 Tioga county, and the north-west part of Potter. 

 In the high ground of Potter county, the moraine 

 crosses a great continental watershed, from' which 

 the waters flow into the Gulf of Mexico, Lake 

 Ontario, and Chesapeake Bay. The moraine is^here 

 finely shown at an elevation of twenty-five hundred 

 and eighty feet, being higher than elsewhere in'the 

 United States. 



It now enters the state of New York in the south- 

 west corner of Allegany county. Passing still north- 

 west, and entering Cattaraugus county, it twice 

 crosses the winding course of the Allegheny River, 

 east and west of Oleau; then trending to a point five 

 miles north of Salamanca, in latitude 42° 15', it forms 

 a remarkable apex, whence to the Ohio line its course 

 is south-west. Turning at right angles to its former 

 course, the moraine passes south-west through the 

 south-east corner of Chautauqua county, and, keep- 

 ing approximately parallel to the course of the Alle- 

 gheny River, re-enters Pennsylvania in Pine Grove 

 township, Warren county. It crosses the Conewango 

 River seven miles north of Warren; then trending 

 west, still at a general elevation of nearly two thou- 

 sand feet above the sea, it crosses one gorge after 

 another, and forms a line separating not only the 

 glaciated from the non-glaciated region, but also the 

 cultivated from the uncultivated and densely wooded 

 region. It crosses the south-east corner of Crawford 

 county, skirts the north-west and west boundary^of 

 Venango county, crosses Beaver River eight miles 

 south of New Castle, and, traversing the extreme 

 north-west corner of Beaver county, crosses the Ohio- 

 state line in the middle of Darlington township, 

 thirteen miles north of the Ohio River. 



The moraine thus leaves Pennsylvania at precisely 

 the latitude at which it entered the state ; and, it a 

 straight line were drawn across the state between 

 these two points, the line of the moraine would form 

 with it a nearly right-angled triangle whose apex 

 was a hundred miles distant perpendicularly from 

 its base. The total length of the moraine, as here 

 shown, is about four hundred miles. The moraine 

 crosses the Delaware at an elevation of two hundred 

 and fifty feet, the Allegheny at an elevation of four- 

 teen hundred and twenty-five feet, and the Beaver at 

 an elevation of eight hundred feet, above the sea, 

 or two hundred and twenty-five feet above Lake 

 Erie. Upon the high lands it rises higher by a 

 thousand feet or more. 



Coming to the details of the moraine, many of 

 which are of great interest, reference was made t& 

 its fine development in Northampton county, west of 



