GLOSSARIES - Geotechnical Earthquake Engineering - page 498

GLOSSARY 1 FIELD TESTING TERMINOLOGY

Adobe Sun-dried brick composed of mud and straw. Abode is commonly used for construction in
the southwestern United States and in Mexico.
Aeolian (or eolian) Particles of soil that have been deposited by the wind. Aeolian deposits
include dune sands and loess.
Alluvium Detrital deposits resulting from the flow of water, including sediments deposited in
riverbeds, canyons, floodplains, lakes, fans at the foot of slopes, and estuaries.
Aquiclude A relatively impervious rock or soil stratum that will not transmit groundwater fast
enough to furnish an appreciable supply of water to a well or spring.
Aquifer A relatively pervious rock or soil stratum that will transmit groundwater fast enough to fur-
nish an appreciable supply of water to a well or spring.
Artesian Groundwater that is under pressure and is confined by impervious material. If the trapped
pressurized water is released, such as by drilling a well, the water will rise above the groundwater table
and may even rise above the ground surface.
Ash Fine fragments of rock, between 4 and 0.25 mm in size, that originated as airborne debris from
explosive volcanic eruptions.
Badlands An area, large or small, characterized by extremely intricate and sharp erosional sculp-
ture. Badlands occur chiefly in arid or semiarid climates where the rainfall is concentrated in sudden
heavy showers. They may, however, occur in humid regions where vegetation has been destroyed, or
where soil and coarse detritus are lacking.
Bedding The arrangement of rock in layers, strata, or beds.
Bedrock A more or less solid, relatively undisturbed rock in place either at the surface or beneath
deposits of soil.
Bentonite A soil or formational material that has a high concentration of the clay mineral montmo-
rillonite. Bentonite is usually characterized by high swelling upon wetting. The term bentonite also refers
to manufactured products that have a high concentration of montmorillonite, e.g., bentonite pellets.
Bit A device that is attached to the end of the drill stem and is used as a cutting tool to bore into soil
and rock.
Bog A peat-covered area with a high groundwater table. The surface is often covered with moss, and
it tends to be nutrient-poor and acidic.
Boring A method of investigating subsurface conditions by drilling a hole into the earth materials.
Usually soil and rock samples are extracted from the boring. Field tests, such as the standard penetra-
tion test (SPT) and the vane shear test (VST), can also be performed in the boring.
Boring Log A written record of the materials penetrated during the subsurface exploration.
California Bearing Ratio (CBR) The CBR can be determined for soil in the field or soil com-
pacted in the laboratory. The CBR is frequently used for the design of roads and airfields.
Casing A steel pipe that is temporarily inserted into a boring or drilled shaft to prevent the adjacent
soil from caving.
Cohesionless Soil A soil, such as a clean gravel or sand, that when unconfined, falls apart in either

a wet or dry state.
Cohesive Soil A soil, such as a silt or clay, that when unconfined, has considerable shear strength
when dried and will not fall apart in a saturated state. Cohesive soil is also known as a plastic soil, or
a soil that has a plasticity index.
Colluvium Generally loose deposits usually found near the base of slopes and brought there chiefly
by gravity through slow, continuous downhill creep.