GEOLOGY AND THE EARTH

Geology and the Earth

Table of Contents

Introduction3

Discussion3

Scientific Theories6

Overview of Earth Systems8

Principles of Earth History14

Uniformitarianism14

Superposition15

Original Horizontality17

Original Lateral Continuity18

Visualizing18

Cross-Cutting Relationships and Included Fragments19

Biotic Succession21

Conclusion22

References23

Geology and the Earth

Introduction

Geology is the science of Earth. It is the study of all aspects of the planet, including its composition, its structure, the physical and chemical processes that act upon it, its origin, its life forms, and its history.The insight that geologists develop comes from an array of techniques, data sources, and instrumentation. Understanding how Earth systems operate requires assimilation and integration of information from diverse fields of science. Geology, therefore, is really an interdisciplinary science. This paper discusses the field of geology and the Earth.

Discussion

To understand the processes responsible for shaping Earth through time, geologists study Earth in many ways (Figure 1.1). They may study strata in a roadside outcrop or a remote mountain range, they may examine individual crystals visible microscopically in a rock, they may analyze the chemical composition of a fossil or backtrack through Earth's changing temperature regimes by studying cores drilled through glacial ice, and they may study movement along fractures in Earth from seismographs anchored to bedrock or from satellites orbiting the planet. Increasingly over recent decades, geologists have also studied other planets and moons in the Solar System to draw parallels with, and to interpret the context of, the evolution of our planet. Geologists work to understand Earth's past in order to, among other things, recover and responsibly utilize the planet's natural resources, understand what conditions have led to current conditions on the planet's surface and avoid or minimize the effects of natural disasters by separating human civilization from areas historically subject to such problems, and preserve key habitats for Earth's life forms. (Bernard 2008)

Figure 1.1 Geologists at work

[A geologist studying the inclination of strata in a limestone quarry hopes to find clues to the tectonic history of western Brazil]

[B Geologists core a frozen lake in Antarctica for a climate record.]

[C A diver examines living corals and sponges forming carbonate reef rocks in the Mediterranean Sea off the coast of France.]

[D An oil rig in Libya produces petroleum needed for fuel, lubricants, and chemical products such as plastics, textiles, and cosmetics.]

Geologists study Earth's history in many ways. Their interpretations are applied to the recovery of natural resources and predictions about Earth's future.Geologists are concerned with figuring out both the long-term history of evolutionary processes in animals, plants, and other life forms and the evolutionary relationships of those organisms. Information about biologic relationships has medical and agricultural applications, among other uses. In addition to deciphering Earth's past conditions and studying its present conditions, scientists want to successfully predict the future of this planet. To understand how perturbations in Earth systems are likely to change the conditions on Earth in the future, our best guide is to study Earth's ancient history as recorded in rocks, sediments, glacial ice, or other repositories of information.

The science of geology is commonly divided into two broad but overlapping subdisciplines referred to as ...