Long winters result in thick winter deposits, and heavy spring floods cause thick sand layers. If the winter of any year is long at Northampton, it is usually long everywhere in New England; and if the Connecticut has floods, most neighboring drainage systems have them, too. In this way, similar layers, or similar successions of layers, are formed at different places at the same time; and the lake deposits at White River Junction, Deerfield, Hadley, South Hadley Falls, Chicopee and Springfield may be matched and dated with respect to each other. The complete record in the valley shows that, in the vicinity of the Holyoke Range, the lake came into existence about 18,000 years ago.
In each of the clay pits every set of lines exposed on the working faces represents a year, and the deposit as a whole is a calendar—in fact, it is also a thermograph for part of the region’s post-glacial history. Some bands at South Hadley Falls and along the Hadley river bank are highly distorted, and the distorted layers are planed off smooth. Spring sand covers the distorted beds. The disturbance can be attributed to ice which froze to the lake bottom and dragged the clay layers as it expanded and contracted with changes in temperature.
Locally the clays are exceptionally hard about certain centers, forming clay stones or concretions. A willow twig or shell or some organic substance is commonly present at their cores. Groundwater has deposited calcium and iron carbonate about the adjacent clay particles and cemented them into rock.
The Holyoke Range
For years it has been a popular outdoor pastime to “walk the Range.” The distance is neither so great nor the route so rugged that it cannot be covered in the course of an afternoon, even if ample time is allotted for stops at the many lookouts. The latter provide ever changing views of the valley from Greenfield and beyond, to Meriden, Connecticut. The buildings in Hartford are easily visible on a clear day. The trail follows the crest of the Range closely and only rarely leaves the basalt lava flow. The trip is somewhat less arduous from west to east than it is in the opposite direction, and the view from Bare Mountain is a pleasant climax for those ending their hike at the Notch.
At the toll booth the trail leaves the road which ascends to the Mount Holyoke Hotel and angles upward along the mountain slope. Overhead the dark basaltic lava columns rest upon red and white Triassic sandstone, and the path soon crosses the contact between the two types of rocks. A short distance above the contact the trail takes advantage of a col and climbs to the top of the ridge. Down the steep southeasterly slope Mount Holyoke College appears in the distance through a screen of oak trees.
The remainder of the climb is gentle, and soon the path enters the clearing around the hotel. The view is arresting. The Connecticut emerges from behind Mount Sugarloaf, wanders through the Hadley fields, flows through the watergap just west of Mount Holyoke, and disappears far to the south beyond Springfield. Northampton is spread out below. Automobiles on the Hockanum Road look like so many moving dots. The hills between the Range and South Hadley are made of volcanic ash and lava; many have pipe-like cores which were the necks of ancient volcanoes. Off to the east are higher points on the Range which lie on the route to be followed.
The path continues along the crest of the range and descends gradually to the toll road level at Taylor’s Notch. Here it is on sandstone, and the lava-sandstone contact is exposed on both sides of the gap. Sandstone cliffs rise fifty feet high a few yards down the road; and the fine arenaceous character of the rock and its bedding are visible at some distance.
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.