Static or mobile earth: The current scientific revolution

Abstract

THE FIRST STUDENTS of the solid earth were miners. Early they founded the sciences of mineralogy and metallurgy, but their studies were local. In spite of the broader insights of such men as Pliny the Elder, Leonardo, Steno, Agricola, Werner, Cuvier, and Lamarck, it was not until the close of the eighteenth and the early nineteenth centuries that Hutton, Smith, and Lyell demolished semi-religious beliefs in a cataclysmic origin of the earth and established the principles of geology (Adams, 1938). As a result, since 1830, the earth has been regarded as a rigid, stable body whose surface features have evolved slowly by processes which we see in action today. In this belief and with steadily improving techniques geologists have spent the past 150 years mapping the rocks exposed on land. Preoccupation with the beauty and intricacy of these discoveries and confinement to the land surface has prevented mankind from appreciating how little of the whole earth is visible. The inaccessibility of most of the earth is a limitation which has prevented geologists from developing general theories. One cannot discover everything about an egg by examining only one-third of its shell. The first precise and general theories of the earth were formulated in the seventeenth century by William Gilbert, Newton and Halley from their investigations of the earth's magnetic and gravitational fields. Unfortunately their elegant theories were not matched by the development of good instruments until a few years ago. Whereas early geologists rapidly accumulated good data, but lacked theory, early geophysicists had precise theories, but could not make enough observations; the two groups could not correlate their ideas. Both long remained in ignorance of those greater parts of the earth, its interior and its ocean floors. Only during this century have seismologists discovered how to use earthquake waves, like giant X-rays, to illuminate the dark interior; only since World War II have adequate ships, instruments and expenditures been available to explore the ocean basins. Suddenly within the past two or three years, the wraps are off and we glimpse for the first time the full beauty of the naked earth. The vision is not what any of us had expected from our limited peeps at the constituent parts. The earth, instead of appearing as an inert statue, is a living, mobile thing. The vision is exciting. It is a major scientific revolution in our own time, but before expatiating upon its nature, let us examine the evidence.