In the broadest sense, the science of geophysics is the application of physics to investigations of the Earth,Moon and planets.The subject is thus related to astronomy. Normally, however, the definition of ‘geophysics’ is used in a more restricted way, being applied solely to theEarth. Even then, the termincludes such subjects asmeteorology and ionospheric physics, and other aspects of atmospheric sciences.

Why is economic geology essential to our progress? It has been said that agriculture is the most basic of man's activities, but in this time of overpopulation and indeed in the preceding centuries it would have been impossible to feed the world's teeming millions without recourse to mining and the use of minerals and metals for ploughing, fertilization, harvesting, food preparation and so on. Indeed, of these two basic industries— agriculture and mining—mining is the older. It started some 500000 years ago when man commenced exploring for tool-making materials — flint, obsidian, quartzite were chipped and ground to sharp cutting edges. Early man found that some localities were richer than others and began to search for these richer deposits, to mine them, establish axe factories and to trade in the finished products. He soon developed an appreciation of their geological occurrence. For example, by 3 000 B.C. large underground flint mines were in operation at Grime's Graves in Norfolk, U.K. and it is clear that the miners had noted that particular horizons in the chalk host rock carried the best and most numerous flints.

The onset and rapid spread of canals across the face of Britain in the late eighteenth century, closely followed by the building of the railway network in the early nineteenth century, were largely responsible for making the study of the strata, or stratigraphy, a subject of both practical and economic value. It is not surprising, therefore, that it was a land surveyor and canal engineer, William Smith (1769–1839), working initially in southern and eastern England, who first worked out that rock strata were not randomly disposed around the country but arranged in a definite order.

This new edition, the 7th, takes note of trends in syllabuses on geological structures and associated problem maps, particularly the move to take less account of the use of structure contours in understanding maps and solving structural problems. There are now two chapters on Map solution without structure contours, the first with simpler maps means that this topic has been introduced at an earlier stage in the book. The second introduces more difficult maps and there are, in these two chapters, three new additional maps. The use of structure contours is not diminished in this edition — the chapter explaining the construction of structure contours is retained with minor additions — as are the maps in the chapter on Economic problems which, reflecting the real world, rely heavily on structure contours for their solution. The other most obvious addition, is that of 16 photographs to illustrate geological features as they are introduced. There are a number of minor additions to the text. In respnse to many requests over the years, this edition now contains completed sections of every map (where a section was required) in addition to the two given in the 6th Edition. Solutions to the maps in Chapters 2 and 11 are also included in the appendix. I would like to express may thanks to my coauthor for his contribution, particularly his photographs, and to former colleagues for all their help in the past in providing the foundation on which this present edition is based. <...>