New Britain herald., 1927-07-23
NEW BRITAIN LIES
ON VOLCANIC ROCK
But No Extinct Craters Are
Found Within 60 Miles

Were any of the hills In this part
Of Connecticut ever VOLCANOES? Thi.
question In one often asked by New
Britain people, especially when they
learn that all the trap rock so COM
origin. Mount Lamentation in Meri.
den is often cited as an example OF
an extinct volcano, evidences OF
eruptive force being visible there.
But was it?
There was much volcanic" &C.
E; tivity in the region during what is
called Triassic time, but the word
volcanic" does not necessarily mean
that there was actually volcano.
| The word Is used by biologists to
/ cover all movement OF the heated
! magInas (lavas) within the earth,
| whether they pour out a volcano,
| well out more quietly through fs-
sures in the earth, or flow through
zones of weakness In the earth's
structure below the surface.
! The first two types are said to be
! 'extrusive" in origin, the third "in-
: trusive."
/; The case OF Mount Lamentation
appears to be slightly different from
! any Of these. The finding of frag-
/: mentary rocks of foreign character
in the solidifed traprock on that
mountain has given rise to the be-
| lief that they are fragments thrown
from the crater mouth and covered
by the flowing lava, and the point
I has long been known as 'the vol
cano."
Biologists are OF the opinion.
however, that there was no volcano
there. They believe that a body OF
water existed in that section at one
time and that lava flowed along the
bottom of this. In such case tho
| top and bottom of the lava sheet
would become solidifled quickly by
contact with the chilling water, but
the heat remaining within the sheet
of lava would produce steam in the
mud below. This would act with the
explosive force of a steam engine,
driving upward through the lava
crust into the still molten interior,
carrying mud. water, steam and
chunks OF solidified crust with it, and
| creating such formation as is
found on Mount Lamentation.
| Another spot with volcanic evil
dences is the ravine of Roaring
, brook, but it is believed that the
rock there came through a dixie"
which does not appear to have been
large enough to be part Of an actual
| volcano. The spot is very interest
| ing one despite this, for 1t is the only
! point in Connecticut where the
| actual line Of contact between the
! Triassic trap and the much older
! crystalline rocks is visible. In other
places, such as along the Trinity
, college escarpment in Hartford, the
! trap may be seen resting upon sand
stone, but these rocks were products
Of the same period, whereas the
,, "schists" at Roaring brook are mil
lions of years older. This "uncon-
formity' (break In time between
adjacent rocks) is considered one Of
the most impressive views available
to geological student. The break is
easily detected because the trap is
brownish and the schist gray black.
The crystalline rock is the stump of
| an old mountain.
Where. then. is there a volcano?
1t is considered probable that Mount
Carmel was at one time an active
volcano, and that Mount Holyoke
was another. There is also evidence
tof volcanoes in Cheshire and
Wallingford, but the mountains
| themselves have been worn away
long ago.
Most Of the trap rock around CEN
trail Connecticut occurs in great
sheets which probably flowed out
over the land or pushed through the
rocks under the surface. and that
about New Britain is known to have
been of the extrusive sort. This is
shown by the coarse structure. evil
dence Of quick cooling in the air. In
some places the rock actually has a
porous structure due to the forma-
| ton Of air bubbles during. the quick
! cooling process. These air holes may
be seen in the rocks on Elijah
Rogers farm at Shuttle Meadow and
small fragments Of them picked up
without much searching. Along the
Trinity college ledge the sandstone
over which the lava flowed has been
blackened by the scorching heat. To
the north and south, such as at Tai
colt mountain and Mount Carmel,
may be seen the finer structure OF
intrusive sheets, while a peculiar
cleavage into hexagonal bars is very
noticeable at West Rock. New
! Haven.
There were three sheets Of lava,
the middle one being the largest and
attaining a thickness Of hundreds of
feet in places. All were of the same
chemical composition, being about
half sand with large amounts OF
aluminium and iron and smaller
quantities OF magnesium, cacium
and sodium.
! The western part OF New Britain
lies on traprock which was pro-
duced by the second or main sheet.
Extending from Rattlesnake noun
tain southwark in a wide swath on
! both sides of the New Britain Plain
Vile town line, this formation takes
in the quarries at White Oak, the
Shuttle Meadow and Ozone Heights
region, the jerome street district,
Black Rock, and the territory well
down toward the center. 1t explains
the numerous outcrops which for
merly existed as lodges on Harrison
street, Ledge court (named from it,
land other streets. This sheet ex-
tends south through Berlin, while
another part Of it forms the cliffs in
I I 4 e..