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Research about Connecticut Valley

Source-linked reports with geographic coverage including Connecticut Valley.

3 recordsLinked to original sources
USGS2022

Lateral moraines, ice-dammed lakes, and meltwater-carved channels in the Pelham, Shutesbury, Leverett area of west-central Massachusetts: A record of Connecticut Valley ice lobe retreat

Temporary ice-dammed glacial lakes formed high in the landscape in several westward sloping valleys on the east side of the Connecticut Valley lowland during late Wisconsinan deglaciation. These lakes were impounded by a lengthy lobe of ice that extended farther south in the lowland than at upland retreatal ice-margin positions (fig. 1). The formation, lowering, and drainage of these ice-dammed lakes successively preceded the extension of glacial Lake Hitchcock northward in the Deerfield Basin as the ice lobe retreated to the north of the Holyoke Range. Detailed surficial geologic mapping of the Shutesbury Quadrangle (Stone, J.R., 1978), along with regional compilation for the Surficial Materials Map of Massachusetts (Stone, J.R. and others, 2018), and ongoing compilation of the Quaternary Geologic Map of Massachusetts has established the extent of these lake deposits and locations of their meltwater- carved spillways. However, recently obtained Lidar-derived high-resolution digital elevation model (DEM) images provide new evidence for mapping of previously unrecognized features not visible on traditional 1:24,000-scale, 10-ft contour interval topographic maps. The newly mapped features have less than 10 ft (3 m) of relief and are believed to be successive lateral moraines left behind by the west-northwesterly retreating Connecticut Valley ice lobe. On the Fieldtrip, we will examine deltaic deposits of ice-dammed glacial lakes in the valleys of Amethyst Brook in the town of Pelham and Roaring Brook in Shutesbury and Leverett, as well as their associated meltwater-carved spillways and feeding meltwater channels. Physical aspects of the low ridges interpreted as lateral moraines will be examined on the ground. Much of the landscape in Pelham, Shutesbury, and Leverett is forested, much is classified as open space, and there are many trails.

Massachusetts↗
USGS1947

Geologic features of the Connecticut Valley, Massachusetts as related to recent floods

This report gives the results of a geologic study of certain features that bear upon the recent flood behavior of rivers flowing in the Massachusetts part of the Connecticut Valley. It is in part an outline of the physiographic history of the Connecticut River, a 'history that is treated in progressively greater detail as it concerns events occurring from Mesozoic time to the present, and in part a discussion of erosional and depositional processes associated with the extraordinary floods of March 1936 and September 1938. The Connecticut River flows southward through Massachusetts in a broad lowland area of more than 400 square miles and is joined in this area by four large tributaries, the Deerfield and Westfield Rivers from the west and the Millers and Chicopee Rivers from the east. The lowland area, or :Connecticut Valley province, is flanked on the west by the Berkshire Hills, a, deeply incised uplifted plateau, and on the east by the central upland, or Worcester .County plateau, a lower upland marked by rolling topography. Most of the broad, relatively flat valley floor is underlain by Triassic sedimentary rocks. Rising above it, however, are the prominent Holyoke-Mount Tom and Deerfield Ranges, which consist in large part of dark-colored igneous rocks, also of Triassic age. There is evidence of several cycles of erosion in central western Massachusetts, the last two of which are of Tertiary age and appear to have reached nature and very youthful stages of topographic development, respectively. Immediately prior to the glacial epoch, therefore, the Connecticut River flowed in a fairly narrow, deep gorge, which it had incised in the rather flat 5ottom of the valley that it had formed at an earlier stage. A Pleistocene crustal subsidence probably of several hundred feet, for which there has been only partial compensation in postglacial time, was responsible for the present position of much of this gorge below sea level. That an estuary does not now occupy the gorge is due to a filling by glacial debris, notably by sediments deposited in late glacial lakes. Following disappearance of the last ice sheet and draining of the associated, lakes, the Connecticut River resumed existence and began a new chapter in its history. In those areas where the river regained its preglacial course, it now flows on sediments considerably above the rock floor of the old gorge. Where the gorge was narrow and deep, the upper parts of its walls have confined the postglacial river within rather narrow limits, as in the northern part of the state. Where it was sufficiently wide to be filled by glacial sediments over large areas, the postglacial river has meandered broadly, as in the area north of the Holyoke-Mount Tom Range. In two areas in Massachusetts and in one immediately south in Connecticut, however, the river was forced from its preglacial gorge, and its new channel has been superimposed on bedrock, with development of rapids and falls. Each of these postglacial rock channels acts as a spillway whose level controls the local base level of the river as far upstream as the next spillway. These spillways are not to be confused with other, more spectacular gorges, which are of preglacial origin and in which the present river does not flow on bedrock. The Recent Connecticut has formed extensive flood plains and terraces through repeated sequences of erosion by lateral corrosion and downward scour, followed by deposition of .silt and sand veneers. These features, although irregular in detail, appear to be assignable to five general levels, whose means are approximately 49, 37, 30, 18, and 10 feet above present mean river level. In addition, an 80-foot terrace in the northern part of the valley was left perched, in its present position when the Connecticut abandoned its course over. a rock barrier near Turners Falls in favor of an adjacent much lower gap. The normal terraces and flood plains, slope very gently away from their riverw

Massachusetts↗