As will be apparent upon a study of the accompanying geological map, the geological formations exposed within thirty miles of Birmingham, include the entire stratigraphical succession between the _Cambrian_ and the middle portion of the _Jurassic_, with two notable exceptions. The two formations locally wanting are the _Ordovician_ and the _Old Red Sandstone_. The nearest known _Ordovician_ rocks occur in central Shropshire, to the east of Church Stretton; the nearest _Old Red Sandstone_ beds are met with to the south of the Forest of Wyre. The natural sequence of formations, and the localities where the several formations are most conspicuously displayed, are given in the following table:-- TABLE OF THE GEOLOGICAL FORMATIONS OF THE BIRMINGHAM DISTRICT. MESOZOIC, OR SECONDARY ROCKS. LIASSIC. _Middle Lias_ (_Marlstone_)--Edge Hill, Fenny Compton. _Lower Lias Clays_--Harbury, Rugby. RHŒTIC. _Marls and White Lias_--Harbury, Knowle, Wooten Wawen. TRIASSIC. _Upper Trias or Keuper_: (_a_) _New Red Marl_--Moseley, King’s Norton, &c., &c. (_b_) _Lower Keuper or Waterstones_--Birmingham, Warwick. _Lower Trias or Bunter_: (_a_) _Upper Mottled Sandstone_--Harborne, Edgbaston, Hockley. (_b_) _Pebble Beds and Conglomerate_--Sutton Park, Smethwick. (_c_) _Lower Mottled Sandstone_--Clent Hills, Stourbridge. PALÆOZOIC, OR PRIMARY ROCKS. PERMIAN, OR DYASSIC. (_a_) _Permian Breccia_--Clent Hills, Northfield. (_b_) _Red Sandstones and Marls_--Halesowen, Enville, Rubery. CARBONIFEROUS. (_a_) _Upper Coal Measures with Spirarks Limestone, &c._--Sandwell, Arley. (_b_) _Lower Coal Measures_--Oldbury, Bilston, Hawkesbury. (_c_) _Millstone Grit_--Absent near Birmingham, present near Colebrookdale. (_d_) _Carboniferous Limestone_--Absent. OLD RED SANDSTONE OR DEVONIAN Absent near Birmingham, present in Forest of Wyre. SILURIAN. (_a_) _Ludlow Shales and Limestones_--Sedgley Hill. (_b_) _Wenlock Shales and Limestone_--Dudley Hill, Wren’s Nest, Walsall. (_c_) _Woolhope Beds_--Barr and Rubery. (_d_) _Llandovery or Mayhill_--Rubery. ORDOVICIAN. Absent. CAMBRIAN. _Upper Cambrian_: (_a_) _Tremadoc Beds and Lingula Flags._--Shineton, Nuneaton, Lower Lickey, and Malverns. FUNDAMENTAL, CRYSTALLINE AND IGNEOUS ROCKS. (_a_) _Charnwood Volcanic Rocks_--Charnwood Forest, Caldecote Hill, The Wrekin. (_b_) _Malvern Crystalline Rocks_--North Hill, Hereford Beacon, &c. THE FUNDAMENTAL CRYSTALLINE AND VOLCANIC ROCKS OF THE MALVERNS, THE WREKIN, AND CHARNWOOD FOREST.