Page:Cornwall; Cambridge county geographies.djvu/37

 NAMES OF SYSTEMS Recent Pleistocene Pliocene Miocene Eocone SUBDIVISIONS Metal Age Deposits Neolithic ,, Palaeolithic ,, Glacial Cromer Series Weybourne Crag Chillesford and Norwich Crags Red and Walton Crags Coralline Crag Absent from Britain Fluviomarine Beds of Hampshire Bagshot Beds London Clay Oldhaven Beds, Woolwich and Reading Thanet Sands [Groups Chalk CHARACTERS OF ROCKS Superficial Deposits Sands chiefly Clays and Sands chiefly ' Cretaceous 1 Upper Greensand and Gault 1 Chalk at top Lower Greensand Sandstones, Mud and Weald Clay Clays below Hastings Sands ) / Purbeck Beds Portland Beds g> Kimmeridge Clay ^4 Corallian Beds Q B Jurassic Oxford Clay and Kella-,vays Rock Cornbrash Shales, Sandstones and Forest Marble _ (j Great Oolite with Stonesfield Slate Inferior Oolite Cfl Lias Upper, Middle, and Lower / Rhaetic Keuper Marls Triassic Keuper Sandstone I Upper Bunter Sandstone Red Sandstones and Marls, Gypsum and Salt Bunter Pebble Beds 1 Lower Bunter Sandstone Permian {Magnesian Limestone and Sandstone Marl Slate Lower Permian Sandstone Red Sandstones and Magnesian Limestone ICoal Measures Sandstones, Shales and Millstone Grit ( Coals at top Carboniferous Mountain Limestone f Sandstones in middle Basal Carboniferous Rocks ) Limestone and Shales below > Devonian f H ?? er 1 Devonian and Old Red Sand- stone ( Lower ) Red Sandstones, . Shales, Slates and Lime- stones i- Silurian ( ? dl, ow , B | d 5 I Sandstones, Shales and Wenlock Beds f Thin Limestones I Llandovery Beds > 5 OH Ordovician i Caradoc Beds | Shales, Slates, { Llandeilo Beds f Sandstones and I Arenig Beds ' Thin Limestones Cambrian (Tremadoc Slates ) Lingula Flags I Slates and Menevian Beds f Sandstones Harlech Grits and Llanberis Slates ) i Sandstones, Pre- Cambrian No definite classification yet made Slates and ( Volcanic Rocks
 * Oolitic Limestones