Gravel road embankments in low-lying areas. Cellular confinement systems can be used to prevent the washboarding effect. The gravel used consists of varying amount of crushed stone, sand, and "fines". Fines are silt or clay particles smaller than , which can act as a binder. Crushed stone is used because gravel with fractured faces will stay in place better than rounded river pebbles. A good gravel for a gravel road will have a higher percentage of fines than gravel used as a subbase for a paved road. This often causes problems if a gravel road is paved without adding sand and gravel
Ardleigh Gravel Pit Ardleigh Gravel Pit Ardleigh Gravel Pit is a 1.2 hectare geological Site of Special Scientific Interest south of Ardleigh in Essex. It is a Geological Conservation Review site. The site exposes a succession of Pleistocene levels, with an interglacial between two glacial periods. The interglacial may date back 700,000 years. The site has plant microfossils rare or unique in Britain, and according to Natural England's description in 1992, it may become the type site for a previously unrecognised British early middle Pleistocene interglacial. The site is divided into two areas. The main one is L-shaped, forming the sloping south-east and