Beverly banner. [volume] (Beverly, N.J.) 1877-1964, 1925-04-03

put in place. But the grinding in IT.
self does not seem so difficult. to ex-
plain as the shaping Of the stones with
such accuracy that the ground edges
fit so absolutely together.
Work of Marvellous Skill.
Each terrace consists, roughly speak
ing, of three parasitic wall and the
two distinct layers of earth that fill
the space behind the wall All of the
ruined terraces show the same inside
structure, wherever the walls are re-
moved. The strata that are hidden
than the stone facing.
The underlying stratum, or artificial
subsoil, is composed of coarse stones
and clay, and is covered by layer of
| fine surface soil two or three feet
| thick. The thickness Of the subsoil
layer depends, of course, upon the
height of the terrace. Where clay or
other light-colored material Is used for
| the subsoil, the difference between the
| two layers appears most striking; but
| the finer texture of the upper layer
also renders 1t very distinct.
In height the terraces range usually
| from to IA feet, the width depending
upon the slope. Terraces on very
steep slopes or narrow shelves of rock
are sometimes only or feet wide,
| though the usual range Is from 8 to 10
| feet, or still wider on the more gradual
slopes. Banks Of 20 to 80 terraces are
| not uncommon, while so or more are
| found in many cases. Probably most
of the soil was moved in baskets or
mats carried on mems backs.
Water was brought to the terraces
from the slopes above In artificial
channels or acequias leading down,
often for many miles, from the gorges
of the high mountains, where they in
tercepted perennial streams fed by the
melting Of the glaciers and snow-fields.
Careful provision was made to avoid
erosion of the soil or injury to the
walls.
Long banks of terraces are inter
rupted at intervals by passageways
| that doubtless served the double pur-
pose of roads for reaching the ter
races and of draining channels to bring
down surface water from the slopes
above, and thus avoid the danger of
having the terraces washed away by
heavy rains.
| The handling of the water on the
terraces undoubtedly was greatly ia
cilitated by the fact that the soils in
all the terraced districts are extremely
| tenacious and not readily eroded. A
| few sods or a small ridge of earth will
hold in check a stream of water, even
| with swift current.
Some of the most laborlous terrac-
|, ing is not on the steep slopes, where
| the terraces are high-walled and mar
row, but in the bottoms Of the valleys,
where the terraces are often very
broad. The building of broad terraces
required more labor because 1t In
volved the filling and leveling OF much
| larger areas behind the wallis. Much
of the work could have been avoided
| by making larger numbers Of lower
and narrower terraces, but the walls
would have been more numerous and
would have occupied more Of the sur
| face.
Vast Irrigation System.
With labor very abundant and land
very scarce the ancient engineers fol-
Flowed the plan of making the terraces
/ as broad as possible, sometimes even
to the extent of bringing material and
| filling in behind walls 10 or 20 feet
high. Thus 1t would be very conser-
vative to estimate that the building of
! the broad, valley-bottom terraces In
volved the handling and replacing Of
the earth for an average depth of at
least feet over the entire surface.
This allows feet for the surface lay.
er Of fine soil and at least an equal
depth for the subsoil layer.
The ancient aqueducts of Peru have
challenged the most attention from
former travellers, and they do not be-
come less worthy of admiration be-
cause they are now seen to be only one
feature of highly specialized agricul-
tural system. The construction of the
| irrigation channels was an enormous
undertaking, perhaps not equaled In
any other part of the world. From
the aqueducts alone 1t is evident that
agriculture must have attained a high
development, which may explain why
the other branches Of the art have re-
ceived less consideration.
How numerous and extensive the
ancient aqueducts really were may
never be known, but the subject is
worthy of much more extensive study
than it has received thus far. If the
accounts Of early Spanish writer's are
to be accepted. some Of these aque-
ducts were very long.