Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1885-08-12
For the Dispatch.l
ARTESIAN WELLS.
Article No. s--Archean Rock OF Richmond--
What VIII We Get BY Boring


Article No. s-Archean Rock OF Riehmond--
whs, WIN We Get by sofins'
Richmond, geologically, is situated
at the western outcrop Of the tertiary
and upper mesozaic, all resting on the
archean Tor primary rock. There are
four divisions Of the primary rock. We
think Richmond gneiss (gneiss is strait
fed grapite) belongs TO the lowest for
nation, Laurentian, because it answers
to the description Of the Lauren
tan rather than Of the other
three, but especially because the
celebrated geologist I. Sterry Hunt
saws So" Geological Railway Guide,
page H." We are little particular,
because in the new =" Rogers's Geology
of the yirginias " it is referred to the
Montalban period. Dana says the esti-
mated thickness Of the rocks Of the
Laurentian period is 10000 feet. The
reporters Of the Richmond press have
not been able as yet to interview any
body that can inform the public what
is below the Laurentian.
We would remark that any water OBJ
tanned by boring into this rock must
necessarily come from pocket or a
Gssure, and must necessarily be surface
water. Gneiss and granite--we have
both here--are massive rocks, and not
subject TO any extensive fracture;
none sufficient to bring water from q
distance. There may be depression
in the surface Of the granite embracing
a large area Of country. For instance,
the coal-felds near Richmond are con-
tanned within a depression Of the granite
twelve miles wide and twenty-five miles
long, and some 1000 to 1000 feet deep.
Such localities lose their primary cha
racter and receive other geological
names the coal-feld is marked Juras-I
sic. Our terrain is primary.
The bed Of James river 1t Richmond |
and some distance below is granite.
the granite crops out at Hollywood
and Oregon Hill many feet above the
level of the river, and about four miles
northward it crops out at Young's mill
pond. How deep is the depression be-
tween these points? The granite dis
appears at Oregon Hill, and except the
bed Of the river and little way up
Shockoe creek we have never learned
that it comes to the surface at any
place to the east Of Richmond. Nobody
knows at what depth the granite
may be reached in the valley near
Tanners foundry, or along the course
of Bacon's Quarter branch. Nobody
knows what is the depth of the granite
on the way to the Chickahominy or
there is any dip, nor what is
the dip of the granite eastward toward
the Atlantic. There must be dip to-
wards the sea, because the infasorial
earth (miocene) which is found in our
was brought up from depth
of GAO feet in an unsuccessful attempt
TO get water at Fortress Monroe.
In the absence Of experimental know
ledge we resort to inference. We infer
that level anywhere under Richmond
that corresponds with the granite bed
of James river cannot be much above
the position of our bottom rock, which |
is the bottom rock Of geology. The
highest point in Richmond is about 200 |
feet above the river-bed at Rockets
then boring $50 feet or less, according |
TO the altitude Of the location, willreach
the granite.
" An Artesian well is q well which !
is sunk, or bored, through imperyious
strata" Gmpervious to surface water
from above and TO water under pressure
from below, y $50 as to reach a water
bearing stratum in which the water is
under sufficient hydrostatic pressure to
be forced to the surface, or nearly to
the surface, Of the ground when the
well is opened. The term is not gene
rally employed unless the impervious
strata are of rock and the depth con-
siderable. ''-Ziemsssn, Volume XYIIf.,
page 254.
Considering the character Of the
geology and topography Of Richmond,
especially the near proximity Of the
granite to the surface, we fear that be-
meath our city there are no strata bear
ing water from distance, nor any i'm
pervious interposition of rock or clay
to protect such water from surface con-
tamination.
Recently, near the river bank, the
enterprising proprietors Of our, paper
mill, needing larger quantity of clear
water, effected boring 402l feet deep
in the granite rock the drill encoun-
tered assures and a sufficient supply
was reached. which they obtained by
pumping. Where does this water come
from? Let chemistry decide. 1t does
not come from the river, because it con-
tains, per gallon, more Of one single in
gredient than the total solids in the river
water. 1t does not come from a hole
some distance, because it contains such
large quantity Of chlorides for the
significance Of chlorides see Wanklyn's
Water Analysis, chapter 3)--sixty
times as much as James-river water
and also organic matter in such quantity
and Of such character as betray its
source-the surface water Of the city of
Richmond.
En- ptde Herculem, II. b.
1 ---~on--
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