what is gravel
Gravel /ËÉ¡raevÉl/ ËÉ¡rÃ¦vÉl is composed of unconsolidated rock fragments that have a general particle size range and include size classes from-granule to-boulder sized. Fragments gravel is categorized by The-Udden wentworth scale into granular (gravel 2 to 4 mm or.0 079 to.0 157) in and pebble (gravel 4 to 64 mm or.0 2 to.2 5). in Pay gravel: also known as pay dirt; a nickname for gravel with a high concentration of gold and other precious metals. 2  The metals are recovered through gold panning.