[Illustration: a. _View of Titan's Piazza at Hockanum showing the
columns resting upon the gently inclined sandstone._]
[Illustration: b. _View of the Springfield lowland from the
Westfield marble quarry. The Wilbraham Mts. appear in the distance.
The trap ridge extends through the middle and is breached by the
Westfield River._]
The columns on Titan's Pier lie across the river from the
Northampton-Holyoke road in the narrow gap at Mount Tom station. The
basalt flow is inclined 15° southeastward, and the columns stand
perpendicular to the surface--hence they are inclined with respect to
the water level. Doubtless the devil docked his boat on the gently
inclined rock surface of the cove on the downstream side of the pier.
Titan's Piazza is situated east of the road to the Mount Holyoke House.
It is an extremely narrow ledge backed by a stockade of columns. The
front of the piazza is literally strewn with wreckage from the house,
for a slope over 100 feet high is covered with angular pieces of basalt
which have fallen from the back wall. The lower ends of the columns
break off into shallow hexagonal saucers with the concave sides up. Many
have slid down the slope, to the delight of the birds that bathe in
them. Higher up the cliff, the saucers become deeper, and towards the
top the columns scale on into bullet shaped masses.
_Westfield Marble Quarry_
Anyone who drives westward on the Jacob's Ladder route from Springfield
passes first through the open, rolling country of the Connecticut
Lowland. Hills are in sight, but they seem remote until he leaves
Westfield, and there the upland rises before him like a 900-foot wall.
The road uses the gateway cut in the wall by the Westfield River, and
the drive westward towards the headwaters of the river is one of the
best known scenic attractions in western Massachusetts. But a greater
treat awaits the person who will venture southward on the road along the
Little Westfield River. It follows the canyon brink about 500 feet above
the stream. Near the hilltop, a side road turns north to the Westfield
Marble quarry, which provides a vantage point overlooking fifty miles of
country to the north, east and south.
The Westfield River meanders eastward across the flat lowland. Its banks
are terraced, each level cut in the lake beds or in the delta which the
river built in glacial Lake Springfield. The scalloped margins of the
terraces are the extremities of meander loops which developed when the
river was not entrenched as deeply in the unconsolidated deposits as it
is today.
The flatness of the twenty-mile strip of lowland is impressive, for it
ends only at the Wilbraham Mountains, eight miles east of Springfield.
Beneath the lowland lie soft and gently dipping sandstones and sandy
shales, capped by a thin veneer of lake clays and river sands. The
shales are the youngest Triassic beds remaining in the region, and they
outcrop between Thompsonville and Windsor Locks, Connecticut. Younger
shales above them succumbed to Tertiary erosion.
The Wilbraham Mountains are granite and gneiss which formed the roots of
the ancient Triassic ranges. Their present accordant summits are a
tribute to the leveling activities which running water performed on a
quiescent land, whereas the deep V-shaped valleys incised in the level
summits record uplift and quickened erosion in Tertiary and glacial
time. Indeed, the lowland itself owes its existence to the power of
rejuvenated streams working on non-resisting rocks.
The Holyoke and Mount Tom ranges are visible far to the northeast, and a
chain of low hills connects Tom with the ridges between Hartford and
Avon, Connecticut. These linear hills surmount the lowland because they
are made of basaltic lava, which is better able to resist the rain and
the weather than the sandstones and shales above and below. Scattered
flat-topped hills between Southwick and Granby are sheets of basalt-like
rock called diabase, which was inserted between a sandstone roof and
floor. Nowhere can one better appreciate the highly individualized
imprint which each geological element has made upon the central New
England landscape.
_The Old Lead Mines_
The colonial period in our nation's history was characterized by an
ignorance of its mineral wealth and a dependence upon Europe for most
raw materials, especially essential metals. During the War for
Independence, European supplies were cut off, and Yankee ingenuity had
to make the most of local deposits of metallic minerals. It was not long
before mines were in operation on several lead veins in the Connecticut
Valley, yielding a supply of lead for the duration of the war. But the
mines were small, and most of them were soon abandoned, remaining only
as historical sites, or as collecting localities for the mineralogist.
Five of these old deposits are still accessible: four lie west of the
valley at Loudville, West Farms, Hatfield, and Williamsburg; an
important one is situated east of the valley at Leverett. All are very
similar in geology and mineralogy, yet each possesses its own
individuality.
The Loudville vein was worked intermittently as late as 1861. It follows
a fault fracture between walls of gneiss, but at the southwest end of
the vein some of the minerals are disseminated through the Triassic
sandstone and conglomerate. This feature indicates that the sediments
were unconsolidated at the time of mineralization. The fault zone
resembles many analogous fissures which give forth hot mineral-bearing
waters in the Basin and Range region of Nevada, for the charged waters
have impregnated the sands which cover the fissures.
The Loudville vein contains numerous well-formed crystals. Barite was
the first mineral deposited, and it is readily recognized as a heavy,
easily scratched substance with one set of cleavage planes at right
angles to two others. Gray metallic galena and resinous cleavable
sphalerite or zinc blende occupy much of the space between the barite
plates. Hard hexagonal crystals or white masses of quartz coat and even
replace the barite plates. Spike-shaped crystals of calcite and siderite
line many of the cavities and coat the quartz. A patient search will be
rewarded by the finding of other minerals, including pyrite,
chalcopyrite, pyromorphite, wulfenite, malachite and azurite.
The old shaft has been closed and the tunnel at the river level has
collapsed, hence the only exposures are in the open cuts. The most
interesting is the one at the south end, where the barite plates are
disseminated through the sandstone.
Another series of pits can be found easily about 100 yards west of the
road to West Farms and about one mile north of the Loudville deposit.
The vein attains a maximum width of three feet between walls of gneiss,
and it occupies a fault fracture which seems to be continuous with the
Loudville zone. Included in the vein are many fragments of a black
phyllite resembling the Leyden argillite, as well as pieces of gneiss.
The minerals are identical with those found in the Loudville deposit,
but the specimens of quartz, galena and sphalerite are more spectacular.
The Hatfield vein occurs in a rock of igneous origin, known as the
Williamsburg granodiorite. It is exposed at the west edge of the valley,
about 200 feet from Federal Highway 5, at the northern limit of the
settlement called West Hatfield. The workings are full of water, and the
very thorough mining activities carried on by mineral collectors and by
Smith College and Amherst classes have reduced the waste pile to
negligible proportions. Early collections and records reveal that the
vein is essentially like those farther south. At Hatfield, West Farms
and Loudville the fractures do not parallel the systems in the Triassic
sediments and lavas.
A galena-bearing vein outcrops near the Whately-Williamsburg town line
at the north end of the Northampton reservoir. Leyden argillite forms
the walls of a fault fissure. Barite is absent from this vein, but fine
quartz, pyrite and chalcopyrite coat the walls. Coarse comb quartz
encrusts the older minerals, together with breccia fragments and cubes
of galena. The vein is remote from the valley and differs in mineralogy
and texture from those within the valley. Other deposits like it have
been found in the nearby hills.
[Illustration: Fig. 23. _Geologic map of the region in the vicinity
of the lead veins near Leverett._]
1. Only barite in these veins
2. Best mineral locality
3. Best place to see fault
4. Slickensides and tension cracks show direction of movement on
fracture making opening for vein
5. Best place to see quartz replacing barite along crush zones in vein
The Leverett lead vein is the most interesting of the group because it
is so well exposed that the nature of the vein system is admirably
displayed. The deposit lies in a series of overlapping, nearly vertical
fault fissures in gneiss. Slickensides and tension cracks on the walls
of the veins indicate that the movement was nearly horizontal from
northeast to southwest. Wherever a fracture begins to narrow and close
up, another begins to widen and become conspicuous a few feet to the
northwest of it. Several different fissures appear along the length of
the mineral zone.
The same minerals are present as are found in the Loudville, West Farms
and Hatfield veins, but barite is more abundant and quartz less so.
Numerous cavities lined with crystals indicate that the vein formed
close to the earth's surface. Apparently the minerals entered fractures
situated near the front of a range that bordered the basin in Triassic
time. A fault zone so located would lack the great thickness of rock
that once lay over the gneiss and would be free from any appreciable
overburden of outwash within the Triassic basins.
_The Dinosaur Tracks Near Holyoke_
People still write from as far away as the Rocky Mountains to ask if the
dinosaur footprints beside the Connecticut River are still in place.
They are. Anyone may see them in that triangular area between the Boston
and Maine tracks and Federal Highway 5 about one-quarter mile north of
the entrance to Mountain Park. Marvelous as their preservation from the
assaults of man may seem, it is even more amazing that they should have
been preserved in rock at all.
[Illustration: Pl. 9a. _The dinosaur track preserve at Smith's Ferry
near Holyoke._]
[Illustration: Pl. 9b. _Varved clays or calendar beds on river bank
south of Hadley._]
The footprint beds are shaly sandstones about thirty feet above the
Granby tuff--a bed of volcanic ash formed in late Triassic time. They
are inclined 15° towards the river, and even the higher strata which
form the "Riffles" are footprint-bearing. The sandstones are
ripple-marked, and they contain worm trails and a few casts of salt
crystals. Some beds have impressions of reeds. The footprints range from
half an inch to ten inches in length, and the stride of the larger
animals was from five to eight feet. Most of the tracks are headed up
the present slope, but a few are going in the opposite direction.
The sandstones were laid down as almost horizontal beds of sand which
were occasionally covered and rippled by moving but rather shallow
water. Rushes and reeds, which have left stray impressions in the rock,
grew seasonally in the shallow waters, but in between the periodic rains
and floods, the local climate seems to have been quite dry--and probably
very warm. The sedimentary record suggests a lowland much like some of
the tropical valleys in the West Indies, lying in the rain shadow of
adjacent mountains.
The large tracks invariably have impressions of three toes. Even a
careful search does not disclose the double tracks which would have been
left by quadrupeds, and for years the bipedal impressions were called
bird tracks. But birds have spurs which leave a mark behind the middle
toe; these animals had no spurs and were not birds, but reptiles.
Gregarious animals generally follow a leader, and only an occasional
individual strays from the beaten path. The tracks at Holyoke suggest
that these Triassic reptiles traveled in small herds.
The modern silts of the Connecticut Valley are not a good medium for the
preservation of tracks because they lack coherence, and they drift with
the wind as soon as they dry. Clays in a region of seasonal aridity are
different. They are baked hard in the hot sun, and the water contains
dissolved mineral matter which crystallizes in the clay and sand as the
water evaporates, cementing the particles into a rock-like aggregate.
Impressions in this sort of mud are preserved. The Connecticut Valley
had the right kind of sediment and climate in Triassic time; impressions
of salt crystals can be found in the shales where the tracks are
clearest, not only in this locality but elsewhere in the neighborhood of
Holyoke and West Springfield. These precipitated salts helped hold the
clays together until they were effectively buried, and afterwards a
firmer cement was deposited around the particles.
Footprints are known near South Hadley, at Turners Falls, at Gill, and
along the highway to the French King Bridge; but they do not portray the
character of the animals, their habits and the mode of preservation of
their tracks as effectively as the tracks north of Holyoke. Certainly no
occurrence of tracks _in situ_ is as accessible, and no geological
exhibit in New England has received so many visitors.
_Fossil Fishing_
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.
[Illustration: Fig. 24. _Diagrams showing the stages in development
of topography in the vicinity of the Notch._]
[Illustration: a. _The New England peneplain stage at the Notch._]
[Illustration: b. _The incoherent rocks are removed from the lava
flow._]
[Illustration: c. _The contours of the cliffs are smoothed out._]
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.
Eastward the way again leads upward to the lava and follows the crest of
a low section of the Range, but soon another fault breaks the continuity
of the ridge, and the high top of Flat Mountain stands out on the far
side of a deep hollow. The hollow is underlain by sandstone below the
lava sheet, and the trail follows down the steep dip slope of the beds,
only to ascend again towards the reddish basalt cliffs of the mountain.
At the base of the flow, the bed of a dry brook exposes a mass of frothy
lava.
The best views from the top of Flat Mountain are those along the south
slope of the Range towards Mount Tom, and northward across the Hadley
lowland. The path then turns down the north face of the mountain some
200 yards along the crest from the west end and, passing over a series
of conglomerate ledges underlying the lava, it continues along a wood
road beside a steep-sided brook until it comes to the Bay Road at the
fork to Dwight and Belchertown.
Any nature lover will find the trail very interesting. The views from
the western half are unexcelled. Wild flowers and birds abound along the
less frequented eastern section. Anyone wishing to see how molten lavas
and earth movements in the distant past have influenced the topography
of the present will find the far eastern walk a veritable revelation.