Glossary

A type of sand whose origins are mainly natural geological formations. Examples include material weathered or eroded from rock such as granite or sandstone. Fines may also come from volcanism or rocks pulverized under moving glaciers. Most, not all, abiogenic sand contains silicon-oxygen compounds such as quartz (SiO₂).

Sand formed from a sedimentary rock containing sandstone and at least 25% of the mineral feldspar.

A type of sand that primarily consists of particles made by human activities. Examples include waste products of industrial processes, ash, conders, and artificial grinding of rocks.

An organizm that thrives in sand; also a term used to describe a sand collector. (Syn. psammophile)

Particles of extraterrestrial origin whose size falls within that for sand. Note: micro-meteorites could be considered astrogenic sand.

A type of desert sand which, under the right wind conditions and the presence of avalanching, can produce a noise akin to the barking of a dog. Note: there is a Barking Sands Beach at Kekaha, Kauai, Hawaii.

A type of sand that primarily consists of biological material, plants, or animals. It may be of silicate, carbonate, or other composition. Sources include foraminifera, diatoms, crushed shells, coral gragments, excreted matter from fish.

A form of singing dune that produces a single groaning musical note (most oftehn the key of “g”, “e”, or “f”) with thicker sand layers of dry sand over more wet under-laying layers producing lower notes; generally produced by natural sand avalanches; research suggests the dune must be over 40m tall, with a slope greater than 30 degrees, and the temperature must be relatively hot; boom may resonate longer than the avalanche that created it.

In coastal erosion, the hydraulic or mechanical movement of sand from the accreting updrift side to the eroding downdrift side of an inlet or harbor entrance. Note: this can result from natural or human actions.

A sand sheet of the late Pliestocene period of relatively uniform thickness that covers a large area with slope angles less than 6 degrees and whose topography does not vary by more than about 5m.

A patterned structure of rock or sediments formed by changing currents of wind or water in which layers are formed progressively, burying previous layers and having different orientations than that of the bedform. Note: It often indicates a dune deposit in the rock record. Geologists look for this type of bedding.

Sand sheet or dune deposit formed in the Holocene period by reworking of prior cover sand (Pleistocene).

An expansive geographical area that contains one or more types of sand dunes and groupings of sand formations.

Layered sedimentary rocks such as gypsum or rock salt that form in marine basins which are subject to evaporation.

An accumulation of sand produced by the action of glaciers.

Sand formed from arkose.

Sedimentary particles that settle at the same rate given the same conditions.

A thin, typically <10 mm thick, sedimentary layer.

Compaction process by which sediments or sand layers become sandstone.

Movement of sand along a beach due to waves striking the beach at an angle to the shore. (Syn. littoral drift).

A means of designating colors based on hue, value, and chroma (saturation). Created by Albert H. Munsell (1858-1919) it has been used in charts to describe sand and soil colors. For example, 5YR 5.5/6 is a reddish-yellow hue with a value midway between 5 and 6 and a chroma of 6. By comparison 10YR would be more yellow and less red.

A flat area such as a dry lake or fan. Also called a pan, it may be periodically filled with water that evaporates.

In soil terminology, an area of unconsolidated sand deposits sometimes found in shifting sand dunes. May form during millions of years of weathering. Covering as much s 3.4% of the global land mass, they are also known as arenosols.

An organism that thrives in sand, also a term used to describe a sand collector. (Syn. arenophile).

In ecological systems terminology, a depression left in coastal sand sediments that can lead to the development of an ecosystem.

A basin of collected sand, silt, or clay that exhibits the characteristics of a fluidized bed. A continuous flow of water enters from below and material loosened by the upward flow can reduce the buoyancy of objects. Rapid movement of an entrapped object can increase its tendency to sink, but slow movement may allow it to be freed.

A version of any of the basic dune types in which major and minor slip faces are oriented in opposite directions as a result of changing winds that blow from opposite directions.

A finely powdered abiogenic substance formed by the grinding action of glaciers on rocks or by erosive processes.

A large area of dunes, greater than 100 km².

Undulating areas of sand that are generally less subject to saltation or dune formation because grains are too large or the wind conditions are unfavorable for dune formation. Other factors include vegetation and/or a high water table.

Parallel linear features developed from transverse instabilities of a sand-transporting wind.

A large, wave-like sedimentary feature of sand in relatively shallow water. These can be as much as 100 m in wavelength with amplitudes of about 0.5 m.

A reddish, yellowish, or brownish sedimentary rock formed from sand grains, usually quartz and related minerals.

Triangular sand forms whose upwind apices are composed of some obstructive object that extends above the level of the windblown sand and which creates a widening ‘shadow’ downwind.

A chemical compound consisting of one atom of silicon for every two atoms of oxygen (SiO₂). Notes: this compound is estimated to comprise about 70% of all sand on Earth. The mineral form of the pure compound is called quartz, but there are many varieties of Si-O based minerals that include other elements.

2-63 µm-sized material that may contain mud, soil, or similar. Silt particles are smaller than fine sand.

One of several types of phenomena that occur on sand surfaces and/or dunes; these range from small squeaks when walking on a moist beach, to low drones associated with booming sands in the desert. (See: booming dunes.)

A scale of particle size proposed by C.K. Wentworth to assign certain size ranges of aggregates to certain terms. By decreasing size, these included “bowlder” gravel, cobble gravel, pebble gravel, granule gravel, very coarse sand, coarse sand, medium sand, fine sand, very fine sand, silt, and clay.

Linear features usually formed by saltation, lying perpendicular to the primary wind direction; typical wavelengths 50 - 200 mm; can form in minutes; amplitude 5-10 mm for fine sand, but greater than 100 mm for coarser sand; typical asymmetric profile with 8-10° stoss slope and 20-30° lee slope; small ripples may move across the faces of a larger dune. Note: Similar ripples in sand may also form underwater.