Page:VCH Worcestershire 1.djvu/31

 GEOLOGY" THE records of the ancient history of the earth are written in the various clays, sandstones, Hmestones, and other stony materials of which its solid surface is composed. These are classified for convenience into larger and smaller groups, according to their order of position, and the fossilized remains of plants and animals which they contain. Each group may comprise strata of very diverse mineral character, but the larger divisions mark the chief life epochs of which records more or less complete are preserved in all parts of the world, while the smaller groups indicate the more local conditions of natural history. Thus we refer to the Silurian period as one of the great epochs of geological history, and to the Woolhope Limestone or Ledbury Shales as one of the more or less local conditions in that great epoch. Geological history is for the most part deciphered from ancient sea- beds. The great oceans and the shallow seas are areas in which are ever being deposited various accumulations of sand and shingle, mud or clay, of shell, coral, or organic ooze. The land-surfaces are areas mainly of waste, from which materials are carried away by streams and rivers, or by the sea itself, to be spread over the ocean-bed along with remains of plants and animals that may be carried out to sea, or which live and die in the ocean. The chief areas of deposition on the land are along the courses of rivers and in lakes. In the course of ages all the land-areas would have been wasted away had not disturbances, which have happened again and again, brought old sea-beds or old lake-beds to the surface. There they have been acted upon by rain, and rivers, and glaciers, and have been worn down or eroded. Through subsequent depression, marine and sometimes extensive lacustrine deposits have been spread over the eroded surfaces of the older strata. This has occurred again and again in the area which now forms Worcestershire, and it will be understood that the intervals during which the strata were upheaved to form land are for the most part breaks in geological time, locally unrepresented by strata. Thus it is that while Worcestershire contains a most interesting and varied series of geological records — records which date from the earliest known geological times — yet there are great gaps unrepresented in the county by any geological formation. The following table shows the stratified formations and the igneous rocks which appear at the surface in different parts of the county : — of some MS. Notes prepared by Mr. R. F. Tomes, F.G.S., whose observations are duly- acknowledged.
 * In the parts relating to the Lias and Rha:tic Beds the writer has had the advantage