During the revolution in earth science that has taken place in recent years, studies of the North Atlantic ocean floor and of Iceland have played an increasingly significant role. Icelandic geoscientists have followed, and taken part in, these studies with a keen interest; one of the first tasks of the Geoscience Society of Iceland was to organize an Icelandic symposium on "Iceland and Mid-Ocean Ridges" in 1967. At the suggestion of Dr. G. Pfuason, the Society and various local research institutions formed in 1972 an Organizing Committee for an international meeting on earth science. It was decided that it should be devoted to examining the various expressions of geo~namical forces in the North Atlantic area, in particular at the ocean ridges passing through Iceland. Apart from the scientific content of such a meeting, the organizers also felt it was highly important for scientists from both sides of the Atlantic to meet in Iceland, to become acquainted with recent progress in earth science research there and to coordinate their future research projects in the area. The meeting was held in Reykj avik 1 - 7 July, 1974, and was followed by field trips in Iceland. Generous financial support from the NATO Scient'ific Affairs Division, the Inter-Union Com mission on Geodynamics, and many other sources, is gratefully acknowledged.

This book provides a summary of geodynamic results from Iceland that presently are found in a great number of scientific articles, but have not been collected before in a book. The ever increasing number of scientists interested in geology and geophysics of Iceland should find the book a "must" to gain knowledge about previous work and the status of knowledge about Iceland.

TECTONlCS AND PHYSICS Geology, although rooted in the laws of physics, rarely has been taught in a manner designed to stress the relations between the laws and theorems of physics and the postulates of geology. The same is true of geophysics, whose specialties (seismology, gravimetIy, magnetics, magnetotellurics) deal only with the laws that govern them, and not with those that govern geology's postulates. The branch of geology and geophysics called tectonophysics is not a formalized discipline or subdiscipline, and, therefore, has no formal laws or theorems of its own. Although many recent books claim to be textbooks in tectonophysics, they are not; they are books designed to explain one hypothesis, just as the present book is designed to explain one hypothesis. The textbook that comes closest to being a textbook of tectonophysics is Peter 1. Wyllie's (1971) book, The Dynamic Earth. Teachers, students, and practitioners of geology since the very beginning of earth science teaching have avoided the development of a rigorous (but not rigid) scientific approach to tectonics, largely because we earth scientists have not fully understood the origin of the features with which we are dealing. This fact is not at all surprising when one considers that the database for hypotheses and theories of tectonics, particularly before 1960, has been limited to a small part of the exposed land area on the Earth's surface.

Recently, recognition of the potential role of large igneous provinces in affecting ocean and atmosphere systems and biotic evolutionary pathways has lead to increased interest in this province. This has been further stimulated by the expansion in the search for oil and gas in Mesozoic and Tertiary sediments along the NE Atlantic Margin. An improved understanding of the interaction between igneous and sedimentary processes is vital for the identification of potential hydrocarbon resources.