Troy weekly news. (Troy, Idaho) 1897-1933, 1907-07-05
SPREADING ebert MATERIAL ON A ROAD.

SPREADING ebert MATERIAL ON A ROAD.
appearance. The two rocks differ ma
terlally in their origin. Cherts occur
usually in chalk and limestone forma-
lions and are generally believed to be
formed by a chemical precipitation
from sea water. NOvaculites. on the
other hand, are thought to be true sed-
lmentary rocks, having been formed by
deposits of very fine matcrial-silt and
sand-ln sea water and subsequently
soidifed. The useful qualities Of no
vaculites as ollstOnes for sharpening
fine tools are well known and are due
to the hardness and smoothness of this
rock
In order that road may bind well,
its surface must be composed of fine
particles of suitable rock which form
the bond. If these particles are blown
or washed away they must be replaced,
or the bond will be broken and the
road will ravel. When roads are sur
faced with limestone or ebert a com
paratively light traffic can be depend-
ed upon to supply enough binder to
keep the road from travelling. For this
reason these materials are better adapt
ed to light traffic tcin harder and
tougher rocks
When bank cherts are first spread
upon the road they are sometimes soft
and brittle and apparently almost use
less as road material. but when
the materials are exposed to the action
OF traffic and the elements the surface
soon becomes n solid, compact mass.
Cherts and novaculites are Invariably
found In sedlmentary formations. The
material Is also found sometimes com
pletely covering the ground. sometimes
In the beds OF streams and narrow val
leys, where II has been deposited by
the action of the water, and again in
banks and pockets on hill and noun
tain sides. Cherts are usually found
In nodular masses. but, like novacu-
lites, may occur in angular fragments.
varying in size from about one to six
inches.
Where these materials are found in
banks or the beds of streams they are
commonly called gravel. Creek gravel
formed from ebert or novaculite. is
usually OF uniform size and compare
lively clean, while the bank gravel
often contains earthly matter and fine
particles of the same material The
creek gravel usually wears the best
but II does not bind so readily or form
as smooth surface ms the bank de-
posits. Where both creek and bank
gravel Is available good results can
be obtained 10y using the former for
foundation and the latter for wearing
OF binder course. The writer used
this method at Florence, Ala. with
marked success.
Where the material is plentiful and
where a good quality of bank gravel
Is available for binder it is unneces-
sary to go to the trouble and expense
OF cutting out a subgrade or to pre-
pare earth shoulders. as is done for
regular macadam. If the shoulders
are dispensed with. however Il is alb
solutely essential that the surface
course contain sufficient quantity of
good binding material: otherwise the
BOND Will soon be broken, the material
VIII spread, and much of It will even
tually be forced or washed into the
SIDE bitches. The roadbed should Of
course be shaped with a road machine
before the material is placed and given
slight crown of from three-eishths 10
ohe-half OF an inch to the foot from
The center to the sides. The founda.