EESA06H3 Study Guide - Midterm Guide: Epicenter, Asthenosphere, Himalayas

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Published on 30 Jun 2014
Environmental Science
EESA06 – Textbook Notes
Chapter 1 – Introduction to Physical Geology and the Environment
What is Geology?
-Geology derived from the Greek word geo and logos and means “the study of the Earth”
-Geology came into being in the late eighteenth century
oIndustrial Revolution in northern Europe created a growing demand for energy
and minerals (coal, limestone, iron, water)
Construction of mines, railways, tunnels, canals, brought to light details
of how rocks are arranged below the ground, distance that they varied,
and how they can be matched from one place to another (fossils)
-Earliest Detailed geologic maps – England, 1815 – William Smith
oWilliam Smith – Referred to as “Father of English Geology”
-In North America, geological mapping began in mid-nineteenth century
oSir William Logan (1842) – Founding director of Geological Survey of Canada;
first to describe the geology of Canada
-Age of the Earth has been determined to be at least 4 500 billion years
Moving Continents
-Alfred Wegner – Suggested the movement of continents on the Earth’s surface (early
twentieth century) – Wrote in the 1912 Continental Drift
oRecognized today’s continents had previously been clustered together in a large
land mass, but subsequently moved apart (Pangea)
oDevelopment of Plate Tectonics Theory
Canadian Geophysicist; J. Tuzo Wilson – 1970s; responsible for
bringing together several key elements in “pate tectonics theory”
Time and Geology
-Geology involves vastly greater amounts of time – “deep time”
oSome geological processes occur quickly (Ex. Great landslide, volcano
eruptions); stored energy is suddenly released
-Earth is estimated to be a least 4.55 billion years old (4 550 000 000)
-Fossils in rocks indicate complex forms of animal life have existed in abundance on
the Earth for about the past 545 million years
-Reptiles become abundant about 230 million years ago
-Dinosaurs evolved from reptiles and became extinct about 65 million years ago
-Humans have only been here only about the last 3 million years
What Do Geoscientists Do?
-Traditional geologists – Spent most of their time in the filed looking for tell-tale signs of
minerals (prospecting)
oNow referred to as exploration geologist
oMay work for exploration company (gold, silver, other metals, diamonds)
oGetting around in four-wheel-drive trucks, helicopters, being in touch with
financiers, market analysts, other business professionals
-Geoscientists; Specialize in a number of areas
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oGeochemists; Comfortable working in the ordered environment of the
laboratory, using high-technology equipment to analyze the chemistry of
Environmental Geology; New Challenges for Geoscientists
-New challenge – Finding and managing of drinking water (groundwater) and dealing
with wide variety of wastes (radioactive waste to household (municipal) waste);
environmental geoscientists
What is the Scientific Method?
-Scientific Method – Problem or Question  Methodology/Data Collection 
Analysis/Interpretation  Hypothesis/Hypotheses  Testing  Theory?
-Hypothesis – Theoretical explanation
How did the Earth Form?
-Earth is a solid body, with oceans, an atmosphere and life
-Universe was formed by the clumping together of gas and debris in the aftermath of the
Big Bang that is thought to have occurred some 15 billion years ago
oBillions of galaxies; The Milky Way contains our own solar system and planet
-Solar system consists of the sun and nine planets and space debris, orbiting the sun
oCreated from a cloud of gas and dust particles; nebula
-Acceration – Process of building large bodies of matter through collisions and
gravitational attraction
oDiffering densities of the planets of the solar system show planets differ in
oTerrestrial Planets – Plants formed close to the sun, small, dense, and rocky
(Mercury, Venus, Earth, Mars)
oJovian Planets – Low density planets (Jupiter, Saturn, Uranus, Neptune)
What was the Early Earth Like?
-After the Earth was formed, it collided with a planetismal; Earth’s moon was created
form the debris that was flung off into space
-Differentiation – Process of zonation of different materials within a planet
oHeavier materials (Iron, Nickel) settled toward the planet’s center, lighter
materials (silica, oxygen) rose toward the earth’s surface
-Early heating of planetary interiors generated large quantities of magma, rising to the
surface along fractures produced by meteorite impacts or by tectonic processes
Internal Structure of the Earth
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-Earth is differentiated – intense heat and pressure within the body of the planet gives rise
to “onion-like” layers of different chemical composition and physical behaviour
-No drill has penetrated the crust, the understanding of the Earth’s interior is based on
indirect evidence
oLayers form an innermost core; composed of iron alloy (iron with nickel and
oA mantle; Composed of Fe-Mg silicates
(Forms a rock – peridotite)
oOuter crust; composed of lighter rocks
(basalt, granite)
-Lithospheric Plates – Mantle convection
breaking the crust and uppermost rigid mantle into
large pieces
-Lithospheric plates are pushed around the surface
of the planet over a weak layer called
-Movement of rigid lithospheric plates over the
more mobile asthenosphere is the fundamental
process involved in plate tectonics
Formation of the Early Atmosphere
-Earths early atmosphere derived predominantly
from water and gaseous elements released during
volcanic eruptions in a process called outgassing
-Most outgassing occurred within the first billion
years of Earths history, forming extensive oceans
and lakes, allowing sediments to be eroded and
-Oldest known sedimentary rocks known are
around 3.8 billion years old
-Oxygen rich atmosphere created by evolution of
photosynthetic life forms that could separate
carbon dioxide into carbon and free oxygen
Early Life Forms
-Earliest life forms preserved in geologic record are microorganisms; Prokaryotes
-Prokaryotes were able to trap sediment to grow organic structures; Stromatolites
-Oldest known fossil on Earth are 2.5 billion year old stromatolites found in the rocks of
Australia’s Pilbara shield
-Cambrian explosion  Life forms about 600 million years ago with the appearance of
more complex organisms with backbones and hard shells
oRich repositories of Cambrian-age fossils  Burgess Shale
What is the “Earth System”?
-Earth System is a small part of the larger solar system but has its own component
oSubsystems/Spheres -- Includes atmosphere (gases that envelop Earth),
Hydrospehre (Water on or near the Earths surface), biosphere (living or once
living materials), geosphere (rock or other inorganic Earth materials)
-The entire Earth system is fuelled by two major sources of energy
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