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.