The Austin weekly statesman. (Austin, Tex.) 1883-1898, 1890-01-23
ROAD MAKING.

ROAD MAKING.
Opinion of Prof. Robert T. Hill, the Geolo-
gist, on Material.
Prof. Robert 7. Hill, in his article
on roads, published in the last Uni
versity Bulletin, has this to say of
suitable for road building:
Creek Gravel-In addition to thy
river gravel, which is made up mostle
of the ancient and harder rocks of the
Burnet region, there are good deposits
derived limestone gravel along
most of the creeks which cross from
the Grand into the Black prairie. This
gravel, however, consists of softer
and would only be Of value
for local repairs and not for extensive
construction. The gravel of such
streams as the San Marcos, the Guada-
lupe, of Onion creek and the San Ga
briel are of this character.
MISUNDERSTANDING the most val
liable of all road-making material is
limestone, when we consider its ease
of fracture, its endurance and its COM
pacting qualities. The following vari-
cites are abundant:
Chalks-In the immediate territory
of the Grand Prairie, however, there
is but one species of limestones, and
this is the Austin-Dallas chalk, which
is too soft for matchmaking purposes,
but is admirably adapted in many
cases for the Telford foundation. This
chalk is a stratum of about 600 feet in
thickness, as explained in the descrip-
ton of the subdivisions of the Black
Prairie. The chalk, or "white rock"
as tits called in its natural position,
makes a good foundation, the surface
material often hardening into a sub
stance technically known as "chalk-
PAM" The best streets in Austin are
of this nature, and short section OF
North Avenue between North Con
gress avenue and Colorado street,
makes natural road far superior to
| any that could be artifcially con.
structed. Although the chalk is
hardly worth digging and transport
| ing for great distances, when possible
in laying out roads they should be To-
Gated upon it.
Chalky Limestones = However
abundant the other sources of mate.
rial for road construction in the Black
Prairie region, the great limestone
beds of the eastern margin of the
Grand Prairie will ultimately prove
the cheapest aud most reliable mate
rial. These limestones are generally
chalky limestones, i. e., chalks which
have hardened through change sui
ficiently to be durable for economic
uses. South of the Brazos these lime
stones are directly at the western
edge of the Black Prairie, and il
quantities to macadamize it man,
times over. The first OF these in de
scending order is
The Shoal creek, or red limestone
as seen on Shoal creek in the city O
Austin, and on the south side OF the
river between the international rail
road and Barton springs. Here thu
material is naturally so jointed ant
fragmentary that it would require yer.
little mechanical crushing to reduc,
it to a splendid matchmaking ma
terial. 1t has been used this summeI
to build Telford foundation on thu
road along which it occurs, but as thi
foundation was not surfaced or ma
cadamized, it will be but one winter O
two before it will again be irrevocabl.
buried beneath the black mud. Thi
limestone could be used to great ad
vantage on the principal black prai
rie highways near Austin.
| Washita Limestone-This limeston
occurs beneath and a little to tn
westward of the foregoing, Gaping tn
hills cast of Mount Bonnell and Tay
lor's lime kiln, at Austin. Fort WORT
and Salado are situated upon it. i
is an impure, somewhat arenaceou
material and is moderately soft, bein
intermediate between the Austin chal
and the Shoal creek limestone. 1t
especially well adapted to surfacinf
but should only be used when bette
materials are less accessible.
Other limestones of the Gran
Prairie formation = Beneath tn
Washita and constituting the whole 9
J Western Travis and other countie
there are thousand feet or more {
much harder limestones varying iron
marble to softest chalk, which woul
be available for building every kind {
roads. These limestones are of tn
lithologic character of the Cretaceou
, and Jurasic limestones of France an
Switzerland, out of which some OF tn
excellent roads of those countries ar
} constructed.
Yellow Marls, "Fuller's Earth" an
Oolite.-Alternately with the gres
! strata Of yellow magnetism limeston'
which makes up the mass of Noun
. Bonnell, and at other localities in th
! grand prairies are strata OF laminate