An Introduction to Geology

The science of Geology is concerned with the Earth and the rocks of which it is composed, the processes by  hich they were formed during geological time, and the modelling of the Earth's surface in the past and at the present day. The Earth is not a static body but is constantly subject to changes both at its surface and at deeper levels. Surface changes can be observed by engineers and geologists alike; among them erosion is a dominant process which in time destroys coastal cliffs, reduces the height of continents, and transports the material so removed either to the sea or to inland basins of deposition. Changes that originate below the surface are not so easily observed and their nature can only be postulated. Some are the cause of the slow movements of continents across the surface of the globe; others cause the more rapid changes associated
with volcanic eruptions and earthquakes.