The original simplicity of the geological structure of the floor of the Birmingham District is much complicated by fractures, faults, and unconformities. The Wrekin and the Malverns are both affected by profound dislocations. The South Staffordshire Coldfield is bounded both on the eastward and the westward by faults of more than ordinary magnitude, while a long straight fault more than 20 miles in length runs through the south-eastern part of Birmingham itself, and flings down the _Keuper marls_ of the Warwick plain against the older sandstones of the Birmingham plateau. In the Birmingham District as everywhere in Britain, the _Triassic_ formation rests unconformably upon everything below. At the same time, its members overlap each other more or less irregularly, and shew a rapid diminution in thickness when followed from west to east. Thus it happens that not only do the _pre-Triassic_ rocks make their appearance in their expected positions along the main anticlinal lines, but many of the old ridges of Palæozoic rocks, which rose out of the Triassic waters, have had their enveloping pall of red sandstone removed from their flanks and summits, which have thus been bared once more to the light of day. Such are, in part, the ridges of the Wrekin, the Malverns, the Lickeys, and the Forest of Charnwood. In the valley of the Severn, to the west of Birmingham, the strata run in narrow bands. The central portion of this valley lying between Coalbrookdale and Bridgnorth, to the west of the main anticlinal of the Birmingham district, owes all its striking beauty and variety to the rapid alternations of hard and soft strata which occur within its limits. In the great Midland plain to the east of Birmingham, the strata are spread out in broad sheets. The plain is underlain in great part by the comparatively homogeneous flat lying Keuper marls, with their intercalated bands of harder sandstones. Its scenery is consequently less varied than that of the Severn valley, but it is rich in that sweet sylvan beauty which is almost peculiar to the English landscape, and it forms one broad expanse of gently rolling farmland and woodland, whose green crested waves sweep onward to the east and south, mile beyond mile, till they break against the long shore-like scarp of the harder Jurassics. THE LOCAL ROCK FORMATIONS.