Part 12

At Easthampton the tour turns south on the College Highway (State 10) towards Southampton and Westfield. The road follows the gravel plain which was spread into Lake Hadley by streams flowing out of the western highland. The plain is dissected locally by the Manhan River (15.2 and 18.0) which crosses the road twice, and one small valley near Southampton (17.1) discloses Triassic arkose buried by the sand. The road rises above the lake deposits (17.4) near the Manhan River, and at once glacial erratics become numerous. The "land of stone fences" forms a narrow divide between the Lake Hadley basin and the Lake Springfield sand plain (21.1), which extends south to the valley of the Westfield River. The Holyoke road (22.5), which enters from the left, came over the trap ridge and across the lake plain.

As the College Highway approaches the edge of the Westfield valley (23.6), it slopes steeply down to the level floor cut by the river. It crosses the Westfield (24.5) and comes to the junction (24.9) with the Jacob's Ladder route (Federal Highway 20), which offers another interesting sidetrip into the Western Upland.

The route continues south to the center of Westfield (25.2), leaving the College Highway at the south end of the common. The Springfield road goes around the central square and starts east in the valley which the meandering Westfield River carved out of the Lake Springfield sediments. The terrace levels and the scalloped pattern of the meander scarps are conspicuous along the lowland. The highway crosses the Little Westfield River (26.1) and then the Westfield itself (27.0) just beyond the entrance to Robinson State Park.

Most mineral collectors will instantly recognize a road turning off to the left (27.8) as the way to the Westfield trap quarry. For years this locality has been as important a source of specimens to collectors as it has been of crushed rock to road-builders. Beyond the quarry road the valley narrows, and the terraces close in as the river enters the gap in the trap ridge. The black lava flow crosses the river (28.3) at the Westfield-West Springfield town line, and shortly the upper flow appears, resting on red shales in both railroad and road cuts (29.1). Actually there are two flows separated by an amygdaloidal band in the upper lava series at this place. The highway crosses the Boston and Albany tracks (29.3) and leaves the river. After passing the junction with the Holyoke road (31.0), the highway drops to the upper terrace level on the bed of glacial Lake Springfield (31.4). The upper terrace is narrow here, and the road soon descends to the meander-cut terraces of the floodplain (32.1). The road to Memorial Bridge turns right (32.3) and our route returns to the North End Bridge (32.8).

Westfield to the Westfield Marble Quarry

This is a short drive of 5.7 miles each way from Westfield, with a mile walk from the Little Westfield road to the marble quarry. The view of the Little Westfield gorge and the entire Connecticut Lowland from Meriden to Amherst makes this trip well worth taking.

The tour leaves Westfield on the Jacob's Ladder road and soon reaches the terraced margin (1.6) of the Westfield valley. The numerous benches along the stream banks represent temporary flood-plain levels of the Westfield. The route turns left from the Jacob's Ladder highway (4.0) and parallels the base of the western highland to the Little Westfield road (4.9). Throughout this distance the marble quarry derrick appears on the highland skyline. Our road turns right at the next crossing and winds along the edge of the Little Westfield gorge (see pp. 61-62). The narrow hill road to the marble quarry turns right (5.7), but it is inadvisable to drive. The walk is an easy one, and the view at the top is worth the moderate physical exertion.

Optional Trips

It must be plain, even to the casual reader, that the foregoing pages have been written with self-restraint. Many of the luring side roads were passed without so much as a pause; trips to the Cobble Mountain Reservoir west of Westfield, and to the Quabbin Reservoir east of Belchertown have not even been suggested; some of the main highways were slighted. For anyone who knows the byways and the hidden beauties that can be found in reasonably accessible places, this chapter will seem inadequate and incomplete.

But it would take a volume far beyond the scope of this brief guide to do justice to the scenery, the geography, and the geologic detail of the Connecticut Valley and its bordering uplands. The authors can merely ask the indulgence of those who would like to know more.

Mineral and Rock Collections

Travelers are inveterate collectors of mementos, and those who travel up and down and across the Connecticut Valley and who delve into its geologic history may well be interested in gathering records of its past. The best records are not in notes or printed pamphlets--not even in this volume on the subject; they are to be found imprinted in the rocks and minerals themselves. But the value of records is measured solely by their utility, and utility is achieved by systematic arrangement. So the authors will venture a few suggestions on collecting and arranging the minerals and rocks which are present in the valley and in the bordering uplands.

One mineral may come from a vein, which is the record of a fissure beneath a hot spring; another comes from a dike, which was a molten igneous rock. This specimen is a conglomerate or consolidated gravel washed into place by an ancient stream; that is a slate which was transformed from clay by intense squeezing and shearing. And if these four specimens were to constitute the nucleus of a collection, the need for classification is apparent. The first two are minerals, which are substances of limited chemical composition and well defined physical properties. The last two are rocks, which are aggregates of minerals or of mineral grains. And the minerals may be further classified according to their separate modes of origin. So, too, with the rocks. Their mineral composition indicates some of the conditions which existed where the minerals originated; the shapes of the mineral grains reveal the process which moved them to their present site; and the arrangement of grains discloses the conditions existing during aggregation at this new locality. Mineral make-up, size, shape, and arrangement of the grains provide means of recognizing major rock varieties--namely, sedimentary, igneous and metamorphic types,--and also of reading each rock's history.

THE MINERALS

The vein minerals, which are deposited in conduits for hot spring water, commonly possess attractive crystal forms; they include barite, quartz and amethyst, fluorite, calcite, datolite, galena, sphalerite, pyrite and others almost too numerous to list. Almost equally attractive crystals may be obtained from some metamorphic rocks, in which they have formed as heat and pressure abetted the growth of certain minerals at the expense of their less favored fellows; this group contains garnet, kyanite, chlorite, amphibole, epidote and many others. Less spectacular are the minerals resulting from the decay of rocks by percolating surface water, such as kaolin, limonite, some calcite, and the bright-colored copper carbonates. Two additional types of minerals are formed as the result of normal sedimentary and igneous processes, which will be described at length in connection with these two kinds of rocks. So, after the rock specimens are sorted from the minerals, the latter may profitably be arranged into five groups:

1. The Vein Minerals. 2. The Minerals of Pegmatites and Igneous Rocks. 3. The Minerals of Metamorphic Rocks. 4. The Minerals of Soils and Rock Decay. 5. The Minerals of Sedimentary Rocks.

The Vein Minerals

The mineral list which follows is far from complete; it contains only those minerals which are most commonly found in casual visits to the localities discussed in connection with the local tours of the Connecticut Valley. Additional species are listed and described in any textbook on mineralogy.

QUARTZ is a hard, white or colorless mineral which will scratch glass easily. In the technical language of the crystallographer, crystals are hexagonal or six-sided prisms, terminated by hexagonal pyramids; and the six flat faces which make the sides, together with the six triangular faces which form the apex, are readily recognized. Massive forms break with a curved or conchoidal fracture and were used by the Indians to make arrow-heads. The mineral is very abundant in all the lead veins and trap quarries; and in some of the latter, specimens of the purple variety of quartz, amethyst, are common. A black, smoky variety has been discovered in the pegmatite dikes of the highlands. Chemically quartz is the dioxide of silicon (SiO_2).

CALCITE breaks along three smooth surfaces or cleavage planes. Each surface is rhomb-shaped, and the six rhombic faces fit together into a characteristic rhombohedral form. A knife will scratch the mineral easily. Calcite is abundant in the white veins of the trap quarries and is the principal constituent of the crystalline limestones in the Hoosac Valley between North Adams and Pittsfield. Calcite is a carbonate of lime (CaCO_3).

BARITE resembles calcite because it can be scratched with a knife and has three smooth cleavage planes. It differs in having one cleavage perpendicular to the other two, which intersect at angles of 78°. The mineral is more than four times the weight of an equal volume of water, and it feels heavy. It is found in the lead veins at West Farms, Hatfield and Leverett. In large quantities it has commercial value as a source of the element barium, for it is the sulphate of barium (BaSO_4).

GALENA is the chief metallic mineral in the veins at Leverett, Hatfield and Loudville. It is very heavy and has a metallic gray color; it breaks into perfect cubes. A knife scratches it easily and crumbles it to a black powder. The mineral is a lead sulphide (PbS).

SPHALERITE is a lustrous, resinous brown mineral in these same veins. It cleaves into multi-faced fragments and is softer than a knife. Chemically it is the sulphide of zinc (ZnS).

PYRITE is the deceptive golden-colored, metal-like mineral which has earned the name of "fool's gold." It will scratch glass, and it crushes to a black powder. The materials in it are iron and sulphur (FeS_2).

CHALCOPYRITE resembles pyrite but will not scratch glass and has a greenish yellow color. It is a compound of copper, iron and sulphur (CuFeS_2).

The veins in the Connecticut Valley region contain many other minerals, among which must be mentioned datolite, natrolite, apophyllite, thomsonite, fluorite and babbingtonite in the lavas; and siderite, rhodochrosite, rhodonite, wulfenite and pyromorphite in the older veins of the highlands.

Minerals of Pegmatites and Igneous Rocks

The minerals found in pegmatites are legion. More than thirty can be collected on any trip to Collins Hill near Portland, Connecticut, or to the Ruggles Mine near Grafton Center, New Hampshire. Only the minerals appearing most commonly in pegmatites are described, but a list of others is appended as an aid in consulting a textbook. Igneous rocks contain practically the same suite of minerals as pegmatites, but in smaller grains.