The trail climbs steeply from this col and soon skirts the edge of an abrupt cliff, in which are carved the initials of many hikers who paused on the ledge to rest and to enjoy the panorama. Eastward the path might well serve as the model for a roller coaster in an amusement park. “The Sisters” are a series of hills separated by sharp, deep valleys; and no sooner has one attained a summit than a drop down the other side is in order. Abrupt 30-foot cliffs trending north and south form many of the valley margins; they are smooth joint surfaces where the rock is weak, and where blocks were plucked out by the great Ice Sheet. Each of “the Sisters” has a cleared lookout which affords a new picture of the Hadley-Deerfield lowland to the north. The last lookout is some distance below the succession of summits, and it affords a view to the east. A cliff drops 200 feet vertically, and about one-quarter of a mile farther east other cliffs of red-weathering basalt face towards it. Almost all of the broad, low gap between the cliffs is underlain by a complicated mixture of volcanic ash, agglomerate and irregular lava flows. The cliff itself is thick columnar basalt, and at its base is a coarse sandstone. But the sandstone is thin and disappears in the depression, whereas the agglomerate and lava become very thick and extend northward to the top of “Little Tinker” and the “Tinker.” They are part of an ancient volcanic cone, buried in sandstone both to the east and to the west. Flow structures in the main sheet move away from this center, which is believed to have been one of the volcanoes on the line which supplied the basalt for the great lava field. In the depression, the trail winds between hills of twisted lava and consolidated agglomerate. When the trees are leafed out and the surrounding hills concealed, it is easy to imagine oneself on the slope of a Pacific volcano. The trail divides at the lowest point in the depression, and the less used fork goes north to the Bay Road at the northern base of the Range. The other fork ascends Mount Hitchcock, and at a slight elevation above the low flat it crosses from the agglomerate to the Holyoke basalt sheet. The best lookout on the Range between the Mount Holyoke Hotel and Bare Mountain is on top of Mount Hitchcock. A side trail leads out to a promontory, from which one may peer along the face of the Range, look down upon the “Tinker” and “Little Tinker,” and gaze over the lowland which the Connecticut has excavated in the New England upland through the long course of geologic time. The east slope of Mount Hitchcock descends steeply, and many a hasty hiker has made the trip in less time than he intended. The path drops to a flat which measures about 1,000 feet across, and in which the sandstone lying below the lava sheet is sporadically exposed. Here the thick basaltic lava has been worn away; and erosion ceases both east and west at conspicuous fracture surfaces which locally become fault planes.