Gravel

**Definition and Properties of Gravel**:
– Gravel is a loose aggregation of rock fragments.
– Classified by particle size range, from granule- to boulder-sized fragments.
– Different bulk densities and hydraulic conductivity levels.
– Sometimes distinguished from rubble, which is angular in shape.
– Various scales define gravel based on particle sizes.

**Origin and Distribution of Gravel**:
– Derived from the disintegration of bedrock as it weathers.
– Most common mineral found in gravel is quartz.
– Deposited in various settings like stream channels, alluvial fans, and marine environments.
– Widely distributed, mainly as river deposits and glacial deposits.
– Wind-formed gravel megaripples in Argentina have similarities to those on Mars.

**Production and Uses of Gravel**:
– Major raw material in construction industry.
– Sand and gravel production in the U.S. constituted 23% of industrial mineral production in 2020.
– Almost half of construction sand and gravel used as aggregate for concrete.
– Crushed stone is displacing natural gravel in some regions.
– Types include bank gravel, bench gravel, crushed stone, fine gravel, and pay gravel.

**Geological Aspects of Gravel**:
– Sediments with over 30% gravel become conglomerate rock.
– Conglomerates found in sedimentary rock, usually