Unit 1 The Earth and Earth Systems - Geology

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GEOLOGY - INTRODUCTION

Geology "…a collection of stone books covering thousands of miles of shelving, tier on tier, conveniently arranged for the student."
                ~ John Muir [describing the Grand Canyon]

Note: Geology is the largest of the four topic sections and will be the most time consuming of all the sections. Take the time to put in the effort to get through the geology section in these first week, so that you are not behind for the remaining weeks. Although the next three sections (Hydrology, Atmosphere, and Ecology) will be less time consuming, if you get behind at the beginning it could become difficult to catch up.

The GEOLOGY topic, the first topic of this assignment, will cover five sub-topics. These sub-topics should be covered in the order that they appear in the list below.

1 - Geologic Time Scales
2 - Plate Tectonics
3 - Mineral Identification and Usage
4 - Rock Formation and Cycles
5 - Soil Formation

These Geology sub-topics were chosen for two reasons:

1. To address the goals and standards of Advanced Placement Standards for Environmental Science and the National Science Education Standards (NSES) for middle and high school students.

2. To provide a complete picture of the processes of geology, with regards to shaping our planet and local region. Before we get started studying the processes of geology we would like to offer some information that answers two fundamental questions:

What is Geology and Why study Geology?

What is Geology?

Geology is the science of the earth's history, composition, structure, and associated processes. It draws upon chemistry, biology, physics, astronomy, and mathematics (notably statistics) for support of its formulations. Geology is divided into several fields, which can be grouped under the major headings of physical and historical geology.

Physical geology includes mineralogy, the study of the chemical composition and structure of minerals; petrology, the study of the composition and origin of rocks; geomorphology, the study of the origin of landforms and their modification by dynamic processes; geochemistry, the study of the chemical composition of earth materials and the chemical changes that occur within the earth and on its surface; geophysics, the study of the behavior of rock materials in response to stresses and according to the principles of physics; sedimentology, the science of the erosion and deposition of rock particles by wind, water, or ice; structural geology, the study of the forces that deform the earth's rocks and the description and mapping of deformed rock bodies; economic geology, the study of the exploration and recovery of natural resources such as ores and petroleum and the study of the interactions of the earth's crust with human-made structures such as tunnels, mines, dams, bridges, and building foundations.

Historical geology deals with the historical development of the earth from the study of its rocks. They are analyzed to determine their structure, composition, and interrelationships and are examined for remains of past life. Historical geology includes paleontology, the systematic study of past life forms; stratigraphy of layered rocks and their interrelationships; paleogeography, the study of the locations of ancient land masses and their boundaries; and geologic mapping, the study of the superimposing of geologic information upon existing topographic maps.

Why study Geology?

Early geologic observations of the earth's structure and processes were made by a number of the ancients, including Herodotus, Aristotle, Lucretius, Strabo, and Seneca. Their major contribution is that they attributed the phenomena they observed to natural and not supernatural causes. Many of the ideas expressed by these men did not resurface until the Renaissance Era. Later Leonardo da Vinci correctly speculated on the nature of fossils as remains of ancient organisms and on the role that rivers play in the erosion of land. Agricola made a systematic study of ore deposits. In the early 16th century Robert Hooke and Nicolas Steno both made penetrating observations on the nature of fossils and sediments.

Modern geology began in the 18th century when advances were made in both the field and theoretical realm. In the field, the German geologist Abraham Gottlob Werner performed a great service for the science of geology by demonstrating the chronological succession of rocks. In 1795 the Scottish geologist James Hutton laid the theoretical foundation for much of the modern science with his doctrine of uniformitarianism. The idea that past geologic events can be explained by the forces operating today, that the “The present is the key to the past,” was an important stride. However, nineteenth century geologists assumed that the Principle of Uniformitarianism applied to rates of geologic processes as well as to the processes themselves, and hence that the rates of deposition have always been constant and equal to today’s.

The conclusion has since been made that rates of geologic processes have differed in the past from today’s rates. This means that the relative importance of different geologic processes has probably differed in the past. For example, just because glaciation is an important process today, we cannot assume it has been equally important throughout geologic time. But we can be confident that when glaciation did affect Earth in geologically remote times, the processes and effects of glaciation were the same as processes and effects of glaciation we observe in Antarctica today.

19th Century Geology was influenced by the work of Charles Darwin,enriched by the researches of the Swiss-American Louis Agassiz, and advanced by the work and publications of Sir Charles Lyell whose book Principles of Geology advanced the doctrine of uniformitarianism over the once accepted idea of catastrophism.

20th Century Geology has advanced at an ever-increasing pace, as have most disciplines of science and technology. The unraveling of the mystery of atomic structure and the discovery of radioactivity allowed profound advances in many phases of geologic research by providing, for example, radiometric dating processes as opposed to relative dating techniques. The ability to survey the Earth’s oceans has brought radical changes in the concepts of crustal evolution, seafloor spreading and plate tectonics. With the advent of the space age, geological studies have risen above earth, reached our moon, and traveled to the planets and moons of our solar system. These mission and projects during the 20th century have provided numerous important discoveries such as insight into the early history of near-earth space (the formation of the earth and moon). On-site analyses of Martian soil samples and photographic mapping of its surface have given clues about its composition and geologic history, including the possibility that Mars once had enough water to form oceans. Photographs of the many active volcanoes on Jupiter's moon Io have provided clues about earth's early volcanic activity. Geological studies also have been furthered by orbiting laboratories, such as the Orbiting Geophysical Observatory (OGO) series during the 1960’s and the Polar Orbiting Geomagnetic Survey (POGS) satellite launched in 1990; remote-imaging spacecraft, such as the U.S. Landsat program (Landsat 7, launched in 1999, was the most recent) and French SPOT series (SPOT 5, launched in 2002, was the most recent in the program); and geological studies on space shuttle missions.

The above narration was adapted from the following source: "Geology." The Columbia Electronic Encyclopedia, Sixth Edition. Columbia University Press., 2003. Answers.com 29 Jan. 2007. www.answers.com/topic/geology

At This Point - Please Proceed to the next topic: Geology - Geologic Time Scale