Some of the performances of this great glacier in the region adjacent to the Delaware are remarkable. It has carried huge granite boulders from the far north and planted them all along the summit of the Kittatinny where it crossed. It has torn out big pieces of limestone, some of them thirty feet long, from their beds in Monroe County, north of this range, carried them in the ice more than a thousand feet up its steep northern face and over the summit, finally dropping them on the south side in the moraine in the slate valley of Northampton. These immense limestone rocks made comparatively short journeys, but one ponderous boulder of syenite from the Adirondacks was found in Northampton, well rounded and dressed, having travelled in the ice at least two hundred miles. There has also been found a "glacial groove" upon the rocks of the Kittatinny near the Water Gap, where some ponderous fragment, imbedded in the ice, as it moved along has gouged out a great scratch six feet wide and seventy feet in length. Although this ice had evidently resistless power in its slow motion, yet it seems to have had small influence upon the topography of the country. It appears to have merely "sand-papered" the surfaces of the rocks. It passed bodily across the sharp edges of the upright sandstone strata of the Kittatinny, yet has not had appreciable effect in cutting the ridge down, the glaciated portion east of the "Wind Gap" appearing as high and as sharply defined as the unglaciated part to the westward of the moraine. The glacier made many lakes north of the moraine, due to the "kettle holes" and obstruction of streams by unequal deposits of drift. It is inferred in the estimates of the duration of the glacier, from astronomical data, that the cold period began two hundred and eighty thousand years ago, the greatest cold being many thousand years later. The intense cold began moderating eighty thousand years ago, but the sea of ice remained long afterwards, and steadily diminished under the increasing heat. So many thousand years being required for melting, there are data inducing the belief that the ice-cap did not retreat from this part of the country back to Greenland until within ten thousand or fifteen thousand years ago. Then came the floods of water from the melting glacier, and it is significant that the Indians in the spacious valley northwest of the Kittatinny called that fertile region the "Minisink," meaning "the waters have gone," indicating their legendary memory of the floods following the melting and retreat of the glacier and the final outflow of its waters. THE DELAWARE WATER GAP.