oft clay shales or soft limestone._ Surface usually
fairly well drained, and fairly hard ground. In general,
favorable for trenches and locally favorable for cave
shelters. In some localities underground water prevents cave
shelter construction. The presence or absence of underground
water should always be determined by test shafts or bore holes
in advance of dugout construction.

_Surface formation consisting of weathered zone 1/2 to 1-1/2
meters thick, made up of clay with limestone fragments and
broken rock. Below is compact limestone formation._ The
surface of this formation is usually fairly hard, and well
drained except in wettest season. Trenches built in it require
little revetting; very favorable for cave shelters, but
requires hard rock excavation. Some thin beds of clay occur in
some of the limestone, and at these a water bearing horizon
will be found. Where a limestone formation rests on clay as
near ---- a line of springs or seepages is usually found. Such
localities should be avoided, or the field works placed above
the line of springs or seepages. This formation is best
developed in the plateau west of ----. Here it is covered by
only a thin layer of soil, hard rock being close to the
surface.

The limestones afford the only rock within the quadrangle
which can be used for road metal.

_Quarries_ (in part abandoned).

_Limestone gravel pits._

_Locus of springs and seepages._ These should be avoided as
far as possible in the location of field works, especially of
dugouts. Field works should be placed above the lines of
springs.

The water supply maps with accompanying engineer field notes are models
of concise description of water supply conditions, with specific
directions for procedure under different conditions. A few paragraphs
taken from these notes are as follows:

Ground overlying rock, such as limestone, compact sandstone,
granites, etc., which are usually fractured, is from the
standpoint of underground water, most favorable for siting of
field works. Clay shales and clay hold both surface and
underground water, and are, therefore, unfavorable for field
works. The contact between hard rocks resting on clay or clay
shales is almost invariably water bearing, and should be
avoided in locating field works.