Formation
body of rock identified by lithic characteristics and stratigraphic position; it is usually but not necessarily tabular and is mappable at the Earth's surface or traceable in the subsurface. Smaller than a subgroup
Elbert Formation
Clwyd Limestone Group
Nashua Formation
Pont d'Arcole formation
Spears Group
Ceja Formation
Love Ranch Formation
Bell Top Formation
Melbourne Formation
Purgatory Conglomerate
York Haven Diabase
Ashe Metamorphic Suite
Gore Mountain Garnet
Tin Mountain pegmatite
Castile Formation
Richmond Coalfield
Molas Formation
Kneeling Nun Tuff
Broken Jug Formation
Fence Lake Formation
Kelly Limestone
Coronado Sandstone
Goat Seep Formation
San Gregorio Formation
Wrinkle ridge
White Ledges Formation
Tumbledown Formation
Ash Creek Group
Blackjack Formation
Cornbrash Formation
Sarmiento Formation
Ekofisk Formation
Tor Formation
Cutler Formation
Salamanca Formation
Lupica Formation
Morrison Formation
Gunflint chert
Thracian Meteora
Wedel-sandstone Formation
Eichberg Formation
Solling Formation
Iron-Sandstone Formation
tectonic dislocation
Erfurt Formation
Rutland Formation
Bright Angel Shale
Frenchman Formation
Santa Cruz Formation
Norwich Crag Formation