The geology of the neighbourhood of Birmingham is one of more than ordinary interest, owing to the great variety of geological formations exposed within its area. Its rocky structure was investigated about thirty years since by the officers of the Geological Survey of Great Britain, and its several geological formations laid down upon their maps, and described in detail in their various explanatory memoirs. Some of these publications—notably the maps and descriptions of the South Staffordshire Coalfield—have subsequently become classic in the literature of Geology. Since these publications were issued, however, the science of Geology has made great advances, more accurate and detailed methods of research among the older rocks have been developed, and their application to the study of the strata of the Birmingham district has recently resulted in the detection of several most interesting facts which escaped the notice of the earlier investigators.