Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1912-09-05

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pits, which are frequently termed gla-
eial grasels 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. ! a..
During recent Sologieal 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 adj
vance have been rounded, worn down,
deposited and redeposited with vary.
ing proportions of sands and loans
and clays. thus forming beds of grar-
ell, which are today available for road
building purposes.
Gravel roads and macadam roads
alike have often received sweeping con-
demnatioRs 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 nnacad-
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 piIing 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-
neetion with the construction OF a
gravel road should be done with as
much care and thoroughness as in the
case Of a macadam road. Moreover, in
the one case as in the other specifca-
tions 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
tical wall when it is being excavated
is generally the best. for the reason
that this same binding material will
re-cement the gravel when used for
road building. Is s-sesss:s
} 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
of iron, lime or ferrugineous clay and
In part to the angular shape and size
of the pebbles composing the gravel.
Blue gravel is universally conceded to
be the best for road construction. be-
cause it is. usually derived from trap
rock. AS the pebbles composing the
gravel retain the characteristics which
they formerly possessed as a part OF
the larger rock itself. it follows that as
trap rock is considered an excellent
material for road building, trap rock
gravel should occupy the same relative
rank among the graveis. Limestone is
generally speaking. soft rock, and
consequently limestone gravel, which
Is quite rare, will. usually be found
soft and will wear rapidly. Quartz
possesses practically no binding power,
although it is very hard. Therefore
gravel which contains an exception
ally large percentage of quartz viii not
prove successful. as 1t wilfafail TO con-
soIidate unless it contains .bihang ma
terial. or unless good binder is added
In order that the material may bind
readily the. Rebbles~sborlld- be angular
and >hoGh vary in size SO that the
smaller fragments may Ill the yoids