Part 8

Many years ago men were excavating to lay a foundation for a waterwheel at what was Whittemore's Ferry, three miles north of Sunderland. They made a catch of some of the most ancient fish ever taken in New England, but the fish were petrified and did not put up a fight.

They were found in layers of black shale, in which skeletons and carbonized tissues were well preserved. Of the five genera identified, all but one were ganoids.

The shale accumulated as mud on a Triassic lake bottom, and it was covered by a coarse stream-laid gravel which has since been cemented into rock. The mud was not eroded by the stream which washed down the gravel, and the pebbles are not even impressed into the underlying shale. Apparently the fish perished as the waters evaporated and the lake became a playa flat. The limited variety of fish suggests that the connections with outside regions were restricted, and that living conditions within the basin were rigorous. The situation may have been like that found in the fresh water lakes along the western margin of the Great Basin in Nevada and eastern California.

Other lake deposits with fish remains appear at different levels from Whittemore's Ferry up to the Sunderland Caves. Each is covered by a conglomerate layer, and at each place the lake clays had been partially hardened before the pebbles were washed over them. Seemingly dry alluvial plains followed transient lakes in kaleidoscopic but cyclic succession.

Calendar Beds

The lakes in which the fish lived and died date back to late Triassic time. Much younger were the lakes that followed the continental ice sheets, and in many valley localities these younger water bodies have registered their brief span of geologic life. For they, too, were settling basins for clays, which are characterized by annual depositional bands like the growth rings in a tree. These clays may be examined best in the clay pits at any of the brickyards, particularly at South Hadley Falls, or beside the high river banks rising above the Connecticut flood plain just south of Hadley.

The clays consist of alternating thin, dark, fine bands and thick, light, coarser ones. The coarser bands are sandy, and some of them have ripple-marks. The total number of pairs of beds is the number of years that glacial Lakes Springfield and Hadley inundated the valley, but it is not a simple matter to count them. Actually the lake bottom deposits are but a small fraction of the total volume of material brought to the lake. Lake shore deposits and deltas grew outward and buried the bottom deposits after a few hundred years had passed. Thus in the pits at South Hadley Falls, the clays rest upon glacial gravels, and a scant hundred layers intervene between them and the sands above. Shore encroachment is not encountered at Hadley, but the shallow depth of the present water table hinders deep exploration, and the Fort River has removed many of the upper beds.

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.

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.

Beyond this low notch the trail leads irregularly upward and eventually comes out on Bare Mountain. The top is bare indeed; even scrub oak is absent from the summit. The long south slope of the Range is clearly visible, and to the west is the Mount Holyoke Hotel where the hike started. The Mount Tom Range, with the Connecticut River at its foot, is just to the left. Due south are the towers of Mount Holyoke College and the cities of Holyoke and Springfield. If the day is clear, the tall buildings of Hartford appear in the far distance. Six hundred feet directly below, the highway goes through the Notch, and across the road is the trap quarry in Notch Mountain, which supplies the crushed stone for the local highways. The face of Notch Mountain lies north of the main line of the Range because the basalt sheet has been displaced northward between fault planes that bound the eminences on either side. The notches utilized by the highway and by the power line are due to facile erosion of the crushed rock along the fault planes. Farther to the east, Mount Norwottock rises to the greatest height in the Range, and the view from its summit is at least the equal of that from Bare Mountain. The Hadley lowland stretches northward between the Pelham Hills on the east and the Berkshire Hills on the west, and protruding above its relatively flat surface are Mount Warner, Mount Sugarloaf and Mount Toby. The Deerfield gorge trenches the western upland just west of Sugarloaf, and on the skyline is Glastenbury far off in Vermont.

The downward trail follows the cliff above the highway. The drop is rapid but not precipitous, and soon the western half of the trail is behind.

The east end of the Range, especially beyond Mount Norwottock, is less commonly visited, but it offers much more of the valley's story. Here the Range is more broken than it is in the western half, and the trail winds through valleys for much of the distance. Long gentle slopes from the west lead to mountain summits, and steep eastern descents take the hiker into the valleys. Plainly the walk is much easier from west to east than in the opposite direction.

The trail leads from the crusher scales around the north base of Notch Mountain and thence up the power line to the crest of the ridge. The path lies on conglomerate below the lava sheet through most of the distance and returns to the lava only where it bends eastward along the crest line. Faulting east of Notch Mountain has moved the base of the lava southward until it abuts on the sandstone above the lava occurring west of the fracture. Thus, the entire backslope of the Range along the power line is coarse sandstone, whereas in the woods to the east it is vesicular basaltic lava.

Many small but abrupt descents occur along the path as it follows the ridge eastward. Each of them marks the position of a minor fault, along which the eastern side has been pushed down and southward under the western side. However, the elevation of the trail increases gradually to the summit of Mount Norwottock, which is almost as high as the uplands bordering the valley. If one can momentarily overlook the lowland excavated on the incoherent Triassic sandstones, the regional surface seems to slope gently upward to the east, the north and the west. Far to the east Mount Wachusett rises above the general level, and there in the northeast is Monadnock's sharp cone. On the western skyline Mount Greylock's summit, with the fire tower at the north end, attains prominence as Massachusett's highest peak. The long ridge of Glastenbury and the point of Bald Mountain are clearly visible in the northwest. Far to the south stretches the lowland, and on a clear day Hartford's towers stand sharp and clear against the sky.

The north face of the Range is a sheer 250-foot cliff. The south side is a half-mile-long, 20-degree slope. Eastward the crest terminates in a precipitous drop, and the trail winds down the corner between the north face and the cliffs at the east end. It crosses the contact between the lava flow and the red Triassic conglomerate about 150 feet below the summit. The conglomerate beds are separated by shaly sandstones, many of which have weathered out to make rock shelters; these are the so-called "Horse Sheds" and are said to have been used during Shays' Rebellion.

The great cliff at the east end of Norwottock was caused by the rapid erosion of the sandstones below the lava sheet, which has receded steadily westward as it was undermined. Recession started at a fault plane about halfway between Norwottock and Hilliard Knob, for here displacement pushed the lava down and southward on the east side until the subjacent sandstone was exposed west of the fault. Exposure led to erosion and to recession of the lava cap.

The trail passes through the "Horse Sheds" to the south base of the Range, following the contact of the lava with the overlying sandstone for about one-half mile on the way towards Hilliard Knob. This eminence lies over half a mile north of the crest of the Range, for it has been offset by faulting, much like the displacements near Mount Norwottock and Notch Mountain, and the trail passes suddenly from the conglomerate above the lava flow to the conglomerate below it. Trail markers must be observed closely through this section because many wood roads cross the path.