The Helena independent. [volume] (Helena, Mont.) 1875-1943, 1891-06-15
The West Side Of the Valley the Best
Place to Sink an Ar
tesian Well.
Known and Possible Conditions Of
Obtaining Water In the Priokly
Pear Valley.
Other Resources Which MAY He Developed
Goal Oil, and Gas Likely to
He Found,

In my last article it was shown that the
rocks in the Prickly Pear valley are OF the
same age-rertiary and C~retaceous-and in
the same basin shape as are the rocks in the
Paris and London basins whore SO many
artesian wells have been bored. 1t was also
shown that but one cause could rendsr the
obtaining of artesian wells uncertain. A
gap or break in the rocks forming the basin
might let the waters out, as broken basins
will not hold water. But rock basins like
other basins are sometimes SO mended that
they will not leak. Fine clays will stop the
leaks in a rock basin as effectually as solder
will in y tin basin. 1t ia known that the
Priokly Pear has worn a gap in this basin;
but it ia more than probable that the fine
sediment of the waters in that stream have
SO filed the pores of the sandstone in this
gap, 80 ''puddled it," that the waters in
the sandstone cannot run out at this gap or
break in the rim of the basin. 1t is possible,
but not probable, that a break or crevice
has been formed in tho rocks in this basin,
as many hundreds of crevices have been
formed in the surrounding mountains and
foothills. There is such a crevice or break
running for miles and miles across the
valley of Sun river, and another ACROSS the
Bear creek coal basin. and several such
c~revices filled with basalt across the Mis-
souri, valley above Fort Union. But there
is no evidence of any such break in the
Prickly Pear valley, for the forces which
elevated the surrounding mountains and
foothills and made the breaks anG ~crevices
in their rocks were not exerted on tine rocks
in the valley. And, besides. if any break or
crevice was made in the rocks of this valley
when the mountains we're forced up, and
such crevice was not filled tight by mineral
matter, the sediment of the lake
which afterwards filled the valley for ages,
most probably stopped all leaks SO the
basin will still hold water. If a crevice in
the rocks of the basin, as at N, has been
thus stopped from leaking, we are just as
likely to get a tesian wells as though there
had been no break in the rocks of the basin;
and that break would even make the
chances better for getting artesian water on
tho west side of the valley; for if the gap
cut by the Prickly Pear in tbs east rim of
the basin, does let the water out of the east
side of the basin. it could not let out the
water on the west side of the crevice made
water tight. as shown Of N in the cut.
But there is one other chance eof failure,
which can be avoided, though the tempta-
lion to take the chance Is very great. In
some parts of the valley and especially the
tower portions, there is a thick deposit Of
gravel and boulders above bedrock. The
ooulders often lender it very diff
cult vexatious and expensive to
bore through such surface deposits.
Hence, there is a strong tempta-
ton to choose a location in the higher por-
tions of the valley, near the river, whore
the boulder gravels are not SO thick or are
entirely wanting. In selecting such a place,
there is danger of STARTING in higher than
the rim of the water-tight strata of
the basin, and hence higher than the wator
will rise. This was the cause of the failure
of the deepest we'll in America at st. Louis.
In this case the expert consulted told the
city council a flowing we'll could no be OF
tanned ut tho place selected. because it was
higher than the rim of the basin.
To illustrate this DANCE of failure let us
refer to the accompanying cut of a vertical
section showing the basin shape of the
rock strata in the Prickly Pear valley. IS
represents a stratum of sandstone extend.
ing from the rim of the basin on the west
side under the valley and up to the
rim on the east side; &C represents