St. Johnsbury Caledonian. [volume] (St. Johnsbury, Vt.) 1867-1919, 1892-02-04
SOME THOUGHTS ON THE GEOLOGY
OF ST. JOHNSBURY.

Specimens suitable for a cabinet
are scarcely to be found in St. Johns
bury Back of the plain is one great
rock formation extending for miles.
1t is lime and mica forma ton called
"calciferous mica schist." "Schist"
signifies that it splits, mica" that
mica is in it, "calciferous" means
"lime bearing" Owing to the lime it
crumbles when exposed to the
weather But the lime enriches the
soil and makes it fertile. 1t is the
most extensive rock in the state.
Beautiful cabinet specimens can be
obtained from the granite and marble
works.
Within easy reach of St. .Johnsbury
are trap dikes Of interest. Trap is
very hard rock thrown up from
beneath the earth's crust in assures
or bikes. There is a trap dixie two
miles south of Danville Green. An
other eight inches wide crossing the
road a mile this side of Barnet village,
another eight feet wide west of the
village and one four feet wide at the
mouth of the Passumpsic river
These were mentioned by Zadock
Thompson many years ago. There
are doubtless others. These should
be found and specimens obtained.
Tha f,,- 81,
for studying minerals, which should
be improved. The thing of special
geological interest in St. Johnsbury
is the geological formation of the
plain. All along the rivers Of New
England are formations called ter
races. Some are exceedingly beauti-
full, rising one above another, extend
ing back rods and sometimes miles as
level as art could make them Some
times they are of equal height on
both sides of the river, sometimes I'M
equal or only on one side. These
terraces are the last geological for
nation. Usually there is clay bed
at the bottom, then sand and pebbles,
then yer of cOarser gravel, cobble
stones and sometimes powders, and
lastly soil. They are stratifed or in
layers, the result of action. Beneath
and beyond the terraces is usually
great amount of unstratifed drift
or till covering all the land, consisting
of hard pan or bowlder clay-hard
clay with powders in it, then sand
gravel, rounded stones and powders,
and lastly soil. 1t is estimated that
this drift or till averages fifty feet
There are four terraces in st. Johns
bury, the meadow beyond the depot,
the depot, Railroad street, Pearl
street and the plain. This last was
the first formed and extended to the
cemetery and the upper part of Pad
dock village. The same are seen
beyond the Hastings bridge. Mr..
Lawrence lives on the first or lowest,
Mr. Salina on the second, Mr.. West
on the third, and Paddock village is
the fourth. The Passumpsic river
and the great floods at the close Of
the ice period cut through the high
terrace and reduced the land to its
present shape. We have seen many
terraces, but none so exposed for ex
animation as this. In the summer
season we can look, as it were, into
the very heart of the terrace and SEE
how it was formed. The till and tn,
lower part of the terrace may extend
as much below the Passumpsic rive
as Boynton hill rises above it. Thu
clay at the brick yard is the loves
seen At the foot of the plain hill
on the right are seen large amoun
of cobble stones, some of them six O.
eight inches through, as if farmer
had gathered these stones and dump
ed them there There is no stratifi
cation. Higher up are gravel, peb
bles and cobble stones, usually il
layers. AS we go down Railroad
street we can see the sand beautiful,
strati6ed in layers. On Tasting
street are seen layers of sand ant
clay. We used to think that tn
clay and sand were deposited nea