Figure 44. Summary of Deerfield basin history. Sedimentation in the early fluvial basin
(TS III of Olsen, 1997) begins at ~218 Ma, and is modified through time by formation
and interaction of basin-bounding faults (BBF). Above the unconformity, the basin is
topographically closed, with playas, lakes, BBF fanglomerates, and minor fluvial strata.
Hydrothermal diagenesis of the sands peaked at 185 Ma. Opening of the spreading center
at the Mid-Atlantic Ridge started basin inversion at 180 Ma. The EBF formed after
deposition, diagenesis, and inversion of basin strata (Roden-Tice and Wintsch, 2002).
Figure 43. Schematic tectono-sedimentary evolution of the Sugarloaf Arkose in the
Deerfield basin. In A-D, only active fault scarps, channels, and fans are shown;
abandoned and buried features are not. Channels are darker where paleocurrents are
available. The scale in A applies to all panels. A. Valley rivers flowed SSW down an
early ‘sag’ basin. One or more valley rivers probably were present in areas to the south
now covered or eroded. B. Formation of the Deerfield BBF redirects the valley rivers
and causes east-flowing piedmont rivers to begin building a megafan. C. Propagation of
the Deerfield BBF to the NNE and SSW increases the size of hanging wall
accommodation space and thus the megafan. Alluvial fans build from the fault scarp.
The Central graben BBF (Wise, 1992) propagates NNE as well, and the two faults
overlap at the Amherst block, forming a relay ramp. D. The Deerfield BBF and Central
graben BBF connect across the Amherst block, forming an integrated BBF. Channels are
lighter where paleocurrent data are unknown.
http://scholarworks.umass.edu/cgi/viewcontent.cgi?article=1243&context=theses
10/20/10
Figure 42. Summary cartoon of provenance. ‘Bubbles’ summarize the three source
terranes for the Sugarloaf Arkose. Blue arrows indicate approximate sediment dispersal
paths into the Deerfield basin. B.I.C. is Belchertown igneous complex.
Merrick History of Wilbraham (1963)
Excerpts & Pictures
Table of Contents:
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THE EARLY YEARS AND GROWTH
THE CHURCHES
AGRICULTURE
BUSINESS AND PROFESSIONS
TOWN GOVERNMENT
HIGHWAYS
TRANSPORTATION
PUBLIC SCHOOLS
PRIVATE SCHOOLS
LIBRARIES
CONCERNING HOUSES
COMMUNICATIONS AND UTILITIES
CATASTROPHES AND TRAGEDIES
MILITARY COMPANIES
CEMETARIES
PASTIMES AND PROJECTS
SOME PEOPLE
MISCELLANY
THE BICENTENNIAL CELEBRATION
APPENDIX
North Wilbraham train station about 1890.
Click on the picture to zoom in.
A BRIEF GEOLOGIC HISTORY OF WILBRAHAM (p. 10)
(a unique "scientific" excerpt from an otherwise historical and cultural work)
Wilbraham is situated in such a manner that its area lies within two broad physiographic
provinces that cross Massachusetts from north to south. The Wilbraham Mountains which so
dominate the geography of the town are part of the Central Upland of Massachusetts, while the
portion of the town west of the mountains lies within the Connecticut Valley Lowland.
The rocks of the Central Upland are ancient rocks of sedimentary and igneous origin. Nearly all
have been altered by metamorphism until they bear little resemblance to their original form. A
very large volume of rock has been removed from this upland, including much of the original
extent of the rock formations which remain today. The metamorphism that altered the rocks that
are now exposed over the upland took place before the overlying rock was removed by erosion.
Most of the mass of the Wilbraham Mountains is made up of one rock formation; the Amherst
schist. This rock, where it crops out in ledges and roadcuts, is seen to be a dark grey, coarse
grained, quartz-muscovite schist. It contains some vein quartz, feldspar clots, biotite, hornblende,
and occasionally some graphite. In places it contains dikes and lenses of granite pegmatite that
were forced into it during metamorphism. For the most part, the rock weathers to a grey to greybrown color, although some beds with higher iron content weather to a rusty brown color.
Another schist formation, the Irving hornblende schist, occurs near the base of the Wilbraham
Mountains on the east side. Along most of Twelve-Mile Brook, this rock unit may be found
making up the steep east side of the valley. Where the rock crops out, it is weathered to a dark
grey color. The fresh rock is a schist formed of hornblende or actinolite and angular quartz
grains. The hornblende and actinolite needles lie in the foliation plane of the schist with random
orientations. The rock tends to break along the foliation planes, and is rather resistant to
weathering and erosion.
According to Professor Emerson of Amherst College, these two rocks originated as sedimentary
material deposited in a shallow sea at least 250,000,000 years ago; at about the same time as the
great coal deposits of the southern Appalachians were being formed. Recent research has
indicated that they may, in fact, be even older. The deeper portions of the sea in which the
sediments that formed these rocks were deposited lay west of Wilbraham, and the sediments
themselves were derived from sources in the eastern part of the state. The older hornblende schist
appears to have been a limy sandstone, while the younger Amherst schist seems to have been a
shale with occasional beds of limestone.
Field study of these rocks as they are exposed across the central upland shows that at some time
after their formation they were folded, uplifted, and intruded in numerous places by large masses
of igneous rock. The intruding igneous rock was granitic in character, and migrating fluids from
the intrusions soaked through the older sandstones and shales and helped to alter them to nearly
their present condition. In the Wilbraham area, the intruded mass of igneous rock is known as the
Monson granodiorite. Extreme reaction about the margin of this granitic intrusion seems to have
produced a shell of dark colored rock known as the Dana diorite. The first range of low hills east
of the Wilbraham Mountains is made up of the narrow band of Dana diorite on the west side and
the Monson granodiorite on the east side.
Although both of these rocks are dark grey to black, the Dana diorite is schistose, coarse grained,
and more nearly black, due to its abundance in hornblende. The smaller white, sometimes pink,
grains in the rock are feldspar grains. Biotite, magnetite and several other dark minerals occur in
varying amounts in this rock. The Monson granodiorite is gneissic, finer grained, and a
uniformly lighter grey in color. The dark mineral present is biotite mica, and the lighter
constituents are quartz and feldspar. This rock has been extensively quarried in Monson. The
schistose and gneissic (layered) structure of these rocks indicates that the processes of alteration
by metamorphism continued after these rocks were intruded.
The ancient rocks that are exposed today in the eastern half of Wilbraham and throughout the
Central Upland of Massachusetts were once continuous to the west. The creation of the Central
Upland, and the separation of these rocks from their western counterparts began during the
Triassic Period about 190,000,000 years ago. A great system of fractures developed in the rocks
of this region and movements of these rocks began to take place. Before these movements were
completed the rocks in the area that we now call the Central Upland were uplifted in a lofty
mountain range, and those in the Connecticut Valley Lowland were depressed repeatedly to form
a long troughlike valley running north to south across Massachusetts and Connecticut. The
fracture that marked the east side of this troughlike valley and the beginning of the mountains is
believed to lie buried near the base of the Wilbraham Mountains and to run just east of, and
parallel to, Main Street in Wilbraham.
Westward drainage from those mountains during the Triassic Period carried sediments derived
from weathering and erosion in the mountains into the troughlike valley and spread them over
the valley Boor. Today these sediments are found as the red Sugarloaf arkose and Longmeadow
sandstone, and the red and grey Chicopee shale. Study of these rocks where they are exposed in
the Connecticut Valley Lowland yields an interesting history of the time of their formation.
Two of these formations underlie the lowland portion of Wilbraham. The coarse, conglomeratic
Sugarloaf arkose lies immediately adjacent to the Wilbraham Mountains on the west, and the
younger, finer grained, well sorted Longmeadow sandstone lies mostly buried beneath the
western portion of the town. Deep wells drilled for household use penetrate these red
sedimentary rocks, and reveal their presence beneath the overlying alluvium. On the campus of
Wilbraham Academy, just east of the wooden track, and on bath sides of Monson Road below
Bolles Road, there are outcroppings of the Sugarloaf arkose that exactly mark the eastern
boundary of the Triassic valley, These outcrops contain abundant plant fossils that reveal
something of the nature of the area at the time. The plants therein preserved are marsh plants
characteristic of a warmer and drier climate than that which we experience today. The red color
of the sedimentary rocks, and the manner in which the beds spread out over the lowland area also
indicate a warmer and drier climate than at present.
The crustal movements that produced the Central Upland and Connecticut Valley Lowland were
attended by considerable volcanic activity, Extensive lava flows separate the Sugarloaf arkose
and Longmeadow sandstone elsewhere in the valley, but do not appear to do so in the Wilbraham
area where the Longmeadow sandstone lies directly on top of the Sugarloaf arkose.
Triassic life was abundant, and numerous tracks, trails, and impressions have been found on the
bedding planes of the Triassic sedimentary rocks, particularly in the Longmeadow sandstone and
the Chicopee shale. Two species of molluscs have been identified from outcrops in Wilbraham:
Anoplophora (Unio) wilbrahamensis, and Anoplophara (Unio) emersoni. Otherwise there are
abundant plant fossils of identifiable quality and occasional Dinosaur tracks, and impressions of
insects and crustaceons are found.
After the close of the Triassic period, there seems to have been little geologic activity save long
continued erosion for at least 160,000,000 years, until the advent of glaciation.
About a million years ago the climate of the earth grew much colder than it had been for millions
of years, and the first of a series of glaciers began to grow and spread over large portions of the
earth's surface. Somehow New England seems to have escaped all of the stages of glaciation
except the last one; About 70,000 years ago, the Wisconsin stage of glaciation began and snow
and ice began to accumulate over New England and the northeastern North American Continent
faster than it could melt way in the summers. Gradually the topography of the land -- hills,
valleys, and mountain ranges -- disappeared beneath the deepening ice. Eventually the ice
thickened unbelievably, reaching thicknesses of over a mile in this area, and nearly two miles in
Labrador and eastern Canada. As the ice thickened it also began to move over the land's surface,
outward from it! thickest portions. The ice moved across Massachusetts toward the southsoutheast.
Soil and rock caught up in the moving ice rasped the rocks of the earth's surface. Ir. Wilbraham,
the softer Longmeadow sandstone and Sugarloaf arkose were cut away more rapidly than the
rocks in the Wilbraham Mountains, so that the mountains were carved into sharper relief. The
effects of the rasping of the rocks in the Wilbraham Mountains can be found on the surface of
exposed rock along the crest of the mountain. Where the rock has been exposed for many years,
only the scratches and grooves made by boulders being dragged over the surface of the rock
remain as evidence of the passage of the glacier. But, where the rock has recently been exposed,
its surface frequently shows a polish produced by the Bner particles of rock and soil that were
scraped over it by the moving ice.
The glacier reached its maximum thickness and extent about 35,000 years ago. Thereafter it
continued to advance across this area, but it gradually shrank in size and thickness. The edge of
the shrinking glacier gradually retreated inland from Long Island Sound, reaching this area
perhaps 12,000 to 15,000 years ago, and the area was finally free of ice about 9,000 years ago.
The waters from the melting glacial ice flowed over the land in many directions, and at many
elevations, and at one time or another most valleys and depressed areas were temporarily
Hooded. The entire Connecticut Valley Lowland was Sooded for hundreds of years. The ponded
waters in this lowland reached from Main Street in Wilbraham westward to the foothills of the
Berkshires in Granville and Westfield, and from the Vermont line to south of Meriden,
Connecticut. From the Holyoke Range southward this giant lake is referred to as glacial Lake
Springfield.
The Chicopee River system carried a very large portion of the waters draining into the lake in
this area. The present Chicopee River is only a shadow of its ancestral self. Millions of cubic
yards of clay, silt, sand and gravel that had been dropped over the land's surface by the melting
glacial ice were Bushed into the former Chicopee River and its tributaries. These rivers carried
this material down to the edge of the glacial lake at Wilbraham and Ludlow. Much of the coarse
sand and gravel (from which present day supplies are drawn) was quickly deposited in a delta
that gradually grew westward into the lake for several miles. The finer sand, silt and clay was
carried farther out into the lake before it was deposited. The broad extensive swampy area west
of the Wilbraham Mountains, including Cedar Swamp, was a low area in this great delta, and is
poorly drained today because of the long distance over which the top of the delta extends at a
nearly uniform elevation. The broad flat areas that begin in the western part of Wilbraham and
extend westward through the Sixteen Acres section of Springfield are the top of this great delta.
The higher, rounded hills that project above the general level of western Wilbraham are deposits
of glacial till, a sediment deposited beneath the advancing glacial ice. These hills rose above the
waters of glacial Lake Springfield, and it is possible to find the beach line of the glacial lake cut
into their slopes. The occasional fiat-topped patches of sand and gravel found elsewhere in
Wilbraham, particularly in the valleys east of the Wilbraham Mountains, are related to tributary
drainage when the glacier was melting off the land, and are not directly related to the deposits in
glacial Lake Springfield.
Eventually, and gradually, glacial Lake Springfield drained away as the earth's crust slowly
sprang back into position when relieved of the great weight of ice, the volume of ponded meltwaters from the glacial ice disappeared, and the region began to assume climatic and drainage
characteristics similar to those of the present time. The modern streams began to establish
themselves and to adjust their valleys to present conditions. The melting of blocks of ice
embedded in the delta and remaining after the main glacial mass had melted away left kettleholes scattered over the fiat lands. Crystal Lake near the Academy's art building and Bruuer's
Pond on Main Street opposite Monson Road are ponds that occupy two of these kettle-hole
depressions. Vegetation gradually reclaimed the surface of the land. Except for the valleys east
of the Wilbraham Mountains, and the steep slopes of the mountains themselves, Wilbraham has
been changed very little since the draining of glacial Lake Springfield. The bouldery soils in the
mountain area and on the higher elevations elsewhere in town have developed from the glacial
till left when the glacier melted, and the sandy or muck soils of the lowland areas in the town
have developed from the old lake-bottom sediments. Until enough time has elapsed for the
streams draining to the Chicopee and Connecticut Rivers to deepen their valleys, little geologic
change can be expected in Wilbraham.
History of Wilbraham, by Charles L. Merrick (1963)
Available in hardcover from Wilbraham Atheneum Society
Other Books:
Peck (1913)
Stebbins (1863)
Atheneum Society | Search | Town Tour | Home
Web pages courtesy of wilbraham.com
http://www.wilbraham.com/history/athmerr.htm 10/20/10