Silts with some clay and fine sands and locally some fine gravel and rock débris. These deposits occur principally on summits and slopes, and are probably from 1 to 2 meters thick. Even during dry season (June to September) they retain moisture and afford rather soft ground. In wet season the formation is very soft and often muddy. In many places water occurs along bottom of these deposits. Favorable for trenches, but which require complete revetment, and ample provision for drainage, not thick enough for cave shelters; cut and cover most practical type of shelter.
Clay at surface with clay shales below. This deposit occurs in flats and is usually saturated for a depth of 1 to 2-½ meters, during wet season, for most of the year the surface is soft, but in part dries out in Summer. Deep trenches usually impossible, and even shallow trenches likely to be filled with water; defensive works will be principally parapets revetted on both sides. Cave shelter construction usually impracticable, unless means be provided for sinking through saturated surface zone into the dry ground underneath. Cut and cover usually the most practical type of shelter in this formation.
Clay at surface with calcareous clay shale and some thin limestone layers below. This formation occurs in low rounded hills; surface saturated during wet weather, but terrain permits of natural drainage, and dries out during Summer; during wet season (October to May) the surface zone is more or less saturated, and ground may be muddy to a depth of a meter or more, ground-water level usually within two or three meters of surface. Trench construction easy, but requires complete revetment, and ample provision for surface drainage. Cave shelters can be constructed in this formation where the slope is sufficient to permit of drainage tunnels. The depth to ground-water level should always be determined by test shafts or bore holes in advance of dugout construction.
- Surface formation usually clay 1 to 2 meters in depth; below this is soft 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 ½ to 1-½ 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.