Bismarck daily tribune. [volume] (Bismarck, Dakota [N.D.]) 1881-1916, 1912-04-27

pits, which are frequently termed gla-
cial gravels on account of their direct
or indirect association with ice action,
are quite widely distributed, and these
have been and may be used to a
greater or less extent In road improve
ment.
During recent geological history Of
the continent the Atlantic and gulf
borders have been submerged at inter-
walls. The ocean has advanced inland
a number Of times. During each of
these periods of continental submer-
gence the harder rock remanents along
the inner margins Of the oceans ad-
vance have been rounded, worn down,
deposited and redeposited with vary
ing proportions of sands and loans
and clays, thus forming beds of gray
ell, which are today available for road
building purposes.
Gravel roads and macadam roads
alike have often received sweeping con-
formations as unsatisfactory when the
cause of failure was poor construction
and not the character Of the material
used. The need Of care in grading and
drainage in the construction Of macad-
am roads is being quite generally rec
ognized. but unfortunately many anna
teur road builders seem to think that
gravel roads may be constructed by
simply piling gravel on the surface and
leaving it to be packed by the passing
traffic. In point Of fact, the grading
and drainage and other details in con-
nection with the construction Of
gravel road should be done with as
much care and thoroughness as in the
case Of macadam road. Moreover, In
the one case as in the other specifica.
tons must be adapted to varying local
conditions. OF course, the gravel itself
must be selected with care. That which
contains sufficient quantity of bind.
ing material so that it stands as YER
teal wall when it is being excavated
is generally the best, for the reason
that this same binding material will
the gravel when used for
road building.
There are three important qualities
which should be possessed by road
building gravel-hardness, toughness
and cementing or binding power. OF
these three qualities the last is the
most important. This binding quality
Is due in part to the presence Of oxide
II iron, lime or ferrugineous clay and
In part to the angular shape and size
IF the pebbles composing the gravel.
Blue gravel is universally conceded to
be the best for road construction, be-
sause it is usually derived from trap
:ock. As the pebbles composing the
yravel retain the characteristics which
hey formerly possessed as part Of
he larger rock itself, it follows that as
rap rock is considered an excellent
for road building, trap rock
yravel should occupy the same relative
'ank among the gravels. Limestone is.
speaking, soft rock, and
limestone gravel, which
> quite rare, will usually be found
oft and will wear rapidly. Quartz
Possesses practically no binding power.
Though It is very hard. Therefore
ravel which contains an exception
lily large percentage Of quartz will not
rove successful, as 1t will fail to con-
ohdate unless it contains binding ma-
erial. or unless a good binder is added.
In order that the material may bind
eadily the pebbles should be angular
nd shonld vary in size 80 that the
mailer fragments may fill the voids (