Earth Science 3209 Chapter 1
Notes (4 notes + 1 Xword & review )
Objectives:
1. Define Earth Science (Geoscience). Notes
2. Identify the four major branches of Earth Science and describe how each branch is relevant to everyday life. p. 2 and Notes
3. Explain how knowledge of Earth Science might influence our decisions about how we use Earth’s resources. pp. 2, 4
4. Describe at least two (2) aspects of Earth Science that makes it different from other sciences. Notes
5. Give examples to show how Earth Science is related to other scientific fields. Notes
Defn
Earth Science is the name for all sciences that collectively seek to understand Earth and its neighbours in space. Earth Science has four (4) major branches:
1. Geology – the study of Earth. Geology has been divided in to two (2) areas:
i. Physical geology – examines the materials that
make up Earth and seeks to understand the processes that operate on (e.g.: weathering, erosion) and
beneath (e.g.: mountain building, earthquakes, volcanoes) its surface.
ii. Historical geology – aims to understand the origin and development of Earth and to establish the
chronological (time) order (see Geological Time Scale p. 10) of Earth’s past.
The ability of geologists to predict earthquakes can save lives and greatly reduce property damage.
2. Oceanography – the study of the ocean. It includes the study of the composition and movement of seawater (currents), coastal processes, seafloor topography, and marine life. Oceanographers use chemistry, physics, biology, and geology in their study of the ocean.
Oceanographers use information about currents in the Pacific Ocean to help predict the onset of El Nino and La Nina. This enables farmers to plant crops that can best take advantage of the weather patterns associated with each event.
3. Meteorology – the study of the atmosphere and the processes that produce weather and climate. Like
oceanographers, meteorologists use a number of sciences.
Meteorologists can warn the population of major weather events such as storms, hurricanes, and tornadoes and
enable the people in the affected areas to better prepare for such events.
4. Astronomy – the study of the universe. Astronomers seek to explain the origin and behaviour of the parts of our
solar system and the many other systems that make up the universe.
Astronomers study the paths of meteoroids and comets and can warn the population well before these objects enter our atmosphere.
Activities:
1. Briefly describe the following terms that are related to Earth Science:
Crystallography
Geomorphology
Hydrology
Mineralogy
Paleontology
Petrology
Seismology
Stratigraphy
Volcanology
Sedimentology
2. Topic 5, Unit 1, Edukit
3. Branches of Earth Science Student Worksheet, Edukit
How might our knowledge of Earth Science influence how we use Earth’s resources?
Resources are divided into two (2) major categories – renewable and nonrenewable. We should be aware that as the world’s population rises and the standard of living
increases, our demands on the world’s nonrenewable
resources intensifies. This means that we must turn to more abundant or alternate resources as other resources become depleted. For example, the United States has an ever
increasing demand for petroleum products (oil, diesel, plastics) but limited domestic resources. Geologists have
developed new ways to identify and quantify new sources of petroleum, but the general population is aware that this
resource will be exhausted in the relatively near future. Thus Americans have turned to more abundant sources of energy such as coal and see the need for alternative energy sources such as water, wind, and tides. The need to use
nonrenewable resources more wisely is evident in the
development of more efficient gasoline engines, hybrid cars, and alternative fuel sources for automobiles such as
hydrogen.
How is Earth Science different from other sciences?
1. Earth Science draws from other sciences such as physics, chemistry, and biology to help develop an understanding of Earth.
2. Earth Science requires a consideration of very long spans of time (see beginning p. 9, text). For example, the geological time scale is a very important and useful tool. Radiometric dating is used to determine the age of fossils.
Earth Science uses many of the same approaches and processes that are used in other scientific disciplines. For example, Kepler’s Laws (from physics) are used by
astronomers and chemical tests can be used in the
identification of minerals. It is important to note that, like other sciences, Earth Science depends on large scale cooperative efforts for its advancement. Earth Scientists from all over the world share their data and experiences, and scientists from different countries participate in joint research projects.
Do # 1, p. 29 text.
Objectives:
1. Use the ideas of the Big Bang and of Creationism to help illustrate how new evidence changes scientific models and theories. Notes
2. Describe some explanations of the origin of the solar system. pp. 19-20, Notes, Bible
3. Use the disagreement on the origin of Earth to illustrate the limitations that exist in the application of science and technology to problems.
The Origin of Our Solar System
Watch the video on the Big Bang and read the description of the related nebular hypothesis on pp. 19-20 of the text. The Big Bang gives a short explanation of the origin of the
universe in general and our solar system in particular. Pages 19-20 (nebular hypothesis) concentrate on the origin of our solar system in more detail. See Video The Universe
According To The Big Bang Theory in Movies Folder. See Big Bang Video (Barenaked Ladies) @ Big Bang Song (Universe)
Creationism is the belief in the literal interpretation of the account of the creation of the universe and of all living things related in the Bible (See the Book of Genesis).
If you look at the article Summary of Scientific Evidence for Creation , which compares creationism and evolution (which begins with the Big Bang), you should realize that we
currently do not have the scientific and technological tools to
determine which model (Creation or Evolution) is correct.
Perhaps both are incorrect. There comes a point in both models where some things have to be accepted on faith because our current scientific and technological resources cannot prove or disprove them.
How New Evidence Changes Scientific Models and Theories
If you review the article New Scientific Evidence Proves Ozone Depletion Theory False, you should realize that there are times when new data is collected which contradicts current theories. The article sites evidence that the ozone layer is in fact not being depleted by the use of chlorofluorocarbons (CFC’s) and that periodic fluctuations in the thickness of the ozone layer can be expected. The article even includes a graph showing that the thickness of the ozone layer over Norway has in fact increased in recent years. The point to note is that new evidence can cause a change in our scientific models and theories.
Objectives:
1. Explain the roles of evidence, theories, & paradigms in the development of scientific knowledge. See The Search for Other Solar Systems
2. Explain why and how a particular technology was
developed and improved over time. See The Search for Other Solar Systems
3. Describe and evaluate the design of technological solutions and the way they function, using scientific principles. See The Search for Other Solar Systems
4. Explain why scientific and technological activities take place in a variety of individual and group settings. See The Search for Other Solar Systems
5. Identify examples of Canadian contributions to science and technology. See The Search for Other Solar Systems Read pp. 5-12 for next day.
Objectives:
1. Demonstrate an understanding that uniformitarianism is a fundamental concept of geology, and contrast this with catastrophic and biblical ideas. pp. 5-7
2. Demonstrate an understanding of superposition as a principle in interpreting geology. pp. 7-8
3. State the contributions of earlier scientists with respect to geological time. pp. 3, 5-6
4. Distinguish between absolute and relative time. pp. 7-8 5. Determine age by direct observation, such as counting the
growth rings of a tree or varves (A varve is a layer or series of layers of sediment deposited in a body of still water in one year.).
6. Explain the Law of Superposition. pp. 7-8, 219
In the mid 1600’s James Ussher constructed a chronology of Earth’s history and determined that it was only a few thousand years old (about 6000 yrs old today). His chronology was
accepted by the scientific and religious leaders of the time (the creationists) because the age he gave for Earth was close to that predicted by biblical scholars.
This being the case, supporters of his chronology had to explain the formation of geological landforms such as
mountains and canyons which we now know take thousands or even millions of years to form. Their explanations led to the idea of catastrophism, which is the belief that Earth’s
geological features were the result of great catastrophes. They explained that Earth’s features were formed by sudden,
sometimes large disasters produced by unknown causes that no longer occur.
In the late 1700’s, James Hutton put forth the principle of uniformitarianism. This principle states that the physical, chemical, and biological laws that operate today have also operated in the geological past. It means that the forces and processes (e.g.: mountain and canyon building) that we
observe to be presently shaping Earth have been doing so for a very long time.
Since Hutton’s writings were difficult to read and understand, his ideas did not gain wide acceptance. It was not until after work published by Charles Lyell that uniformitarianism was widely accepted.
It is important to note two (2) things about the principle of uniformitarianism.
i. Although the same forces and processes have been occurring for a very long time, the rate at which these forces and processes have occurred has undoubtedly varied.
ii. There is evidence to suggest that there is a place for catastrophism in our explanation of Earth’s history.
Mass extinctions (e.g.: dinosaurs) can be explained using catastrophism.
Compare catastrophism & uniformitarianism here.
Sample Test Questions
1. With the aid of a specific example, explain how
uniformitarianism can be used to understand past catastrophic events.
2. What scientist was responsible for proposing the principle of uniformitarianism?
a) Darwin b) Hutton c) Wegener d) Wilson
3. Which statement contradicts uniformitarianism?
a) Catastrophic events rarely happen.
b) Processes that formed Earth in the past are no longer happening.
c) Processes that formed Earth are still happening.
d) Things that change Earth cannot be undone.
Activity: A Geo TV Special – Uniformitarianism vs Catastrophism, Edukit
If you examine a cross section of the trunk of a tree, it is
possible to determine the absolute age of the tree by counting the growth rings. By absolute age we mean the exact
numerical age (e.g.: 64 years) of the tree. You can also count
the varves at the bottom of a lake to determine the age of the sediment. Note that a light and dark ring together represent one year of growth (tree ring, left pic) or deposition (lake varve, right pic).
Now suppose you wanted to compare the ages of Mr.
Holloway, Heather Morgan, and Tyler Tucker but you didn’t know any of our ages exactly. You may determine, by looking at or knowing certain characteristics (such as the amount of grey hair or the grade level), that Tyler is younger than
Heather who is younger than Mr. Holloway. While you can tell who is oldest and who is youngest, you cannot tell the exact numerical age (i.e.: the absolute age) of each person. Placing events or items such as rocks in their proper sequence from oldest to youngest without giving their numerical age is called relative dating. In this case, you have determined the relative age of each individual and not the absolute age.
Activity: Relative & Absolute Time Worksheet, Edukit
There is an important law that is used in relative dating. It is the Law of Superposition and it is credited to Nicolaus Steno. The law states that in an undeformed sequence of
sedimentary rocks, each bed is older than the one above it and younger than the one below it. This law is also true for lava flows and ash deposits from volcanoes. Look at Figure 8.2 A
& B on p. 219 of the text. Among these layers the Supai Group is the oldest since it is below the other layers of rock. The next oldest layer is the Hermit Shale, followed by the Coconino Sandstone, the Toroweap Formation, and the Kaibab
Limestone which is the youngest because it is the top layer.
See Relative Dating (slides 1126-1141) under Geological Time Scale on GeoDE.
Another important principle in relative dating is the Principle of Fossil Succession. It states that fossil organisms succeed one another in a definite and determinable order, and
therefore any time period can be recognized by its fossil content. This principle allows geologists to determine that rocks that contain the same types of fossil(s) are roughly the
same age. For example, if two rock layers, one in
Newfoundland and one in Sweden, both contain trilobite
fossils, it is likely that both rock layers are about the same age (i.e. about 443 to 540 million years old).
Do Review Questions 3, 4 p. 29 text.
Objective:
1. Explain the progression in the development of scientific knowledge. pp. 9-11
The Development of Scientific Knowledge
Scientific knowledge is usually developed in the following sequence.
1. Observation/Measurement – This includes the collection of raw data from which theories and laws are formulated.
2. Hypothesis – This is a preliminary, untested explanation for what has been observed and/or measured.
3. Theory – This is a well-tested and widely accepted view that scientists agree best explains the observations and/or
measurements (e.g.: Theory of Plate Tectonics).
4. Law – This is a generalization about the behaviour of nature from which there has been no known deviation after many observations and experiments (e.g.: Newton’s Law of
Universal Gravitation).
There are a few things to note about the development of scientific knowledge.
i. Science rarely proceeds in such an orderly fashion.
Don’t get the idea that the development of scientific knowledge is a rigid, 4-step process. Hypotheses are sometimes incorrect and may have to be revised and tested many times before a theory arises from them.
ii. A theory is not a guess, it is based on a broad base of evidence and can be used to predict future events (e.g.:
Theory of Plate Tectonics). Also note that no theory is perfect and it may not explain everything.
iii. A law is not a mature theory. In other words, theories don’t evolve into laws. Laws are concise statements that summarize behaviour and no known contradictions exist (e.g.: Newton’s Universal Law of Gravitation) iv. To help understand the difference between a theory and
a law, keep in mind that theories EXPLAIN while laws DESCRIBE. For example, the Theory of Plate
Tectonics explains the current location of the continents and can be used to predict their future locations. Newton’s Universal Law of Gravitation describes the mutual attraction of all objects which have mass.
Sample Test Question
What is the normal progression for the development of scientific knowledge?
a) hypothesis – observation – law – theory b) law – observation – hypothesis – theory c) observation – hypothesis – theory – law d) theory – hypothesis – observation – law
Do # 7, p. 29 text.
Read pp. 12-19 for next day
The Geological Time Scale
The geological time scale (see pp. 10, 237) is a scale that divides Earth’s history into different time periods (eons, eras,
periods, and epochs). It was originally developed using relative dating principles. It was only in the 1900’s that radiometric dating allowed absolute dates to be added. The eons represent the greatest amount of time. Eons are divided into eras. The eras are further divided into periods, and the periods are divided into epochs.
Note that the details on the scale do not begin until about 570 million years ago. The nearly 4 billion years before that is divided into 3 eras, but is collectively known as the
Precambrian. It represents about 87% of geological time.
See Geological Time Scale (slides 1090-1125) on GeoDE.
You need to be able to date the following events using the geological time scale and/or other resources such as the Internet.
Event Date Beginning of the Cenozoic Era
Beginning of the Mesozoic Era Beginning of the Paleozoic Era Formation of Oldest Rocks Formation of Earth
Pleistocene Glaciation Oldest Ocean Crust
Extinction of the Dinosaurs
Do # 6, p. 29 text
Objectives:
1. Identify and define the four spheres – atmosphere, hydrosphere, biosphere, and geosphere. pp. 13-14 2. Recognize that the four spheres interact in a cyclic
fashion. p. 13
3. Use the concept of spheres to illustrate and analyze systems. p. 14
Our planet consists of 4 spheres.
1. Hydrosphere – the water portion of our planet. The most prominent feature of the hydrosphere is the ocean, which covers nearly 71% of Earth’s surface and
accounts for nearly 97% of Earth’s water. However, the hydrosphere also includes the freshwater found in
lakes, ponds, streams, glaciers, and in the ground (groundwater).
2. Atmosphere – the gaseous portion of our planet. The air that surrounds our planet is composed of:
i. Nitrogen (78%) ii. Oxygen (21%) iii. Argon (0.93%)
iv. Carbon dioxide (0.035%) v. Others (0.035%)
3. Geosphere – the solid part of the planet. It consists of : i. The core – This is the dense center of Earth and it
consists of two parts; the solid inner core with a radius of about 1216km, and the liquid-like outer core with a thickness of about
2270
km.ii. The mantle – This is the less dense (solid to almost plastic-like) rocky layer beneath the crust with a thickness of about 2885km.
iii. The crust – This is the very thin outer solid layer of Earth with a thickness that varies from 5 to 40 km. It is thinnest beneath the oceans and thickest where the continents exist.
Note: The term lithosphere refers to the crust and part of the upper mantle.
4. Biosphere – This is the part of the geosphere, hydrosphere, and atmosphere where life is found.
It is important to note that these four spheres are not
independent structures. They constantly interact with one another to produce a highly complex system.
Sample Exam Question
1. The air we breathe is composed mostly of which gas?
(A) argon
(B) carbon dioxide (C) nitrogen
(D) oxygen
Do # 8, p. 29 text.
Objectives:
1. Use the rock cycle diagram to show the relationship among the three classes of rocks. pp. 15-17
2. Using the rock cycle as an example, analyze a system and its components. pp. 15-17
The rock cycle illustrates the interrelationship among the rock types (see Figure 1.12, p. 16 text).
The core, mantle and crust of Earth can be envisioned as a giant rock recycling machine. However, the elements that make up rocks are never created nor destroyed although they can be redistributed, transforming one rock type to another.
The recycling machine works something like this. Liquid (molten) rock material solidifies (cools) (crystallization) either at or below the surface of Earth to form igneous rocks.
Igneous rocks formed below Earth’s surface may be exposed by processes such as uplifting which formed mountains. The exposure of igneous rocks to weathering at Earth’s surface breaks them down into smaller grains producing soil. The grains (soil) are transported (erosion) by wind, water, and gravity and deposited (deposition) as sediments. The sediments are deposited in layers and become compacted and/or cemented (lithification) forming sedimentary rocks.
Variations in temperature, pressure, and/or the chemistry of the rock can cause chemical and/or physical changes in igneous and sedimentary rock to form metamorphic rocks. When exposed to higher temperatures or even greater pressure,
metamorphic rocks (or sedimentary or igneous rocks) may be partially melted resulting in the creation of igneous rocks once more, starting the cycle all over again. See
http://www.classzone.com/books/earth_science/terc/content/in vestigations/es0602/es0602page02.cfm
And
http://www.kscience.co.uk/animations/rock_cycle.htm
There are some alternate paths that rocks can follow in the rock cycle. For example, igneous rock that has not been
exposed to the surface may experience great pressure and high temperatures during processes such as mountain building and may be transformed directly into metamorphic rock instead of being weathered and eroded at Earth’s surface and becoming sedimentary rock. As well, metamorphic and sedimentary rock may be exposed, weathered, and eroded, eventually becoming sedimentary rock, instead of becoming igneous rock. (See slides 215-243 DVD)
Sample Exam Questions
1. Why does the rock cycle have no beginning and no end?
2. Sequence the following events: sedimentary rock forms, weathering occurs, heat and pressure are applied, igneous rock forms, erosion occurs, metamorphic rock forms,
deposition occurs, sediments are formed, melting & cooling occurs.
3. Use the rock cycle to explain how a single piece of sedimentary rock can contain bits of other sedimentary, igneous, and metamorphic rock.
4. Which statement is TRUE about the rock cycle?
a) Igneous rocks lithify to form sediments.
b) Igneous, sedimentary, and metamorphic rocks are all subject to metamorphism.
c) Magma crystallizes to form both igneous and metamorphic rocks.
d) Weathering affects only sedimentary rocks.
Objectives:
1. Explain the origin of the solar system using the solar hypothesis (solar nebular hypothesis). pp. 19-20
2. Use the solar nebular hypothesis to illustrate the roles of evidence, theory, and hypothesis in the
development of scientific knowledge.
3. Use the solar nebular hypothesis to illustrate how scientific knowledge develops as a result of careful
observation and experiments, and peer review by groups and individuals throughout the world working
cooperatively.
4. Relate the formation of the geosphere to the origin of the solar system. p. 20
5. Describe the segregation (layering), due to radioactive decay and gravitational forces, of the
geosphere into layers having different physical properties.
pp. 20-23
The Solar Nebular Hypothesis
This proposal suggests that planets, sun, and moons of our solar system condensed from a huge cloud of gases (mostly hydrogen and helium and a small percentage of other heavier elements).
About 5 billion years ago (the approximate age of Earth), this huge cloud began to contract under its own gravitational
influence and also began to rotate. As it contracted, it began to spin faster and faster and to flatten into a disk. Most of the material in the cloud was pulled towards the center and eventually became our sun. However, the rotational motion kept some material from moving to the center and this material eventually became the planets and moons, or was swept out into space by solar winds (see Figure 1.14, p. 19 text).
Note that this hypothesis was very important in the
development of Earth’s history as it determined that Earth was actually much, much older than the age indicated by
creationists. See
https://www.youtube.com/watch?v=PL3YNQK960Y Sample Exam Question
Explain the origin of the solar system using the Solar Nebula hypothesis.
Activity: Solar Nebular Student Worksheet, Edukit
The Formation of Earth’s Layered Structure
After Earth was formed, its interior began to melt due to the energy released by the decay of radioactive elements and the colliding particles. This melting allowed the denser elements, like iron and nickel, to sink to the center, while the lighter rocky components floated outward toward the surface. The result was a sorting of material by density, with more dense material toward the center of Earth surrounded by less dense material. This created layers of shells, each with different properties.
The creation of layers of materials also allowed gases to
escape from Earth’s interior. These gases were initially swept into space by the solar wind, but as Earth cooled and molten material solidified, the gases released were retained in the atmosphere. This gradual release of gases from molten rock is known as outgassing. Gases such as carbon dioxide, hydrogen sulfide, sulfur dioxide, water, and others are still being
released from volcanoes today. Watch here
Do # 11, p. 29 text.
Read pp. 19-27 text for next day.
Objectives:
1. Diagram or model the interior of Earth, labeling all the principal parts and showing the approximate thickness of each layer. p. 22
2. Differentiate among the layers of Earth and describe their characteristics. pp. 20-23
Read pp. 20-23, 476 and complete as much of the table below as possible.
Core Crust
Inner Outer Mantle Asthenosphere Continental Oceanic Depth (km)
Thickness (km) Principal Materials State (solid or liquid) Relative Density Temperature
C
Other
Activity: Earth’s Interior Student Worksheet, Edukit See pic here.
Sample Exam Question
1. What best describes the lithosphere?
(A) a liquid layer within the mantle (B) a rocky layer within the mantle
(C) the outer, liquid portion of Earth’s core (D) the rigid, rocky, outermost layer of Earth
2. What elements are found in Earth’s inner core?
(A) carbon and nickel (B) iron and nickel
(C) silicon and iron (D) sulfur and nickel
Do #’s 5, 12, 13 p. 29 text
Objectives:
1. Describe the Theory of Plate Tectonics. p. 23
2. Describe the three (3) types of plate boundaries. pp. 24-27
The Theory of Plate Tectonics
By 1968, enough data had been gathered to explain how the continents drifted apart after the break up of Pangaea. The explanation for the movement of the continents is called the Theory of Plate Tectonics. It essentially states that Earth’s outer shell consists of about 20 rigid slabs called plates. These plates are constantly in motion relative to one another (see Figure 1.16, pp. 24-25 text). The plates vary in size and include the very large Pacific plate and the adjacent, smaller Nazca plate. Note that these plates often contain both
continental and oceanic crust. This contrasts with Alfred Wegener’s continental drift hypothesis that said only the continental crust moved.
Recall that Earth’s rigid outer shell is called the lithosphere and includes both continental and oceanic crust as well as part of the upper mantle. Below the lithosphere is the plastic-like asthenosphere. It is this fluid region that allows for the
movement of the solid plates above it. Keep in mind that the plates in the theory of plate tectonics are rigid so any two places on the same plate should always remain the same distance apart. However, the distance between places on
separate plates should vary as the plates move relative to each other.
The edges of the plates are called plate boundaries. It is along the plate boundaries that most of Earth’s seismic activity,
volcanoes, earthquakes, and mountain building occur.
Three Types of Plate Boundaries
There are three (3) main types of plate boundaries.
1. Divergent Boundaries – occur where plates move apart.
These boundaries occur mostly at ocean ridges and allow molten material to come from inside Earth and create new see floor (see Figure 1.16A, p. 24 text). See
http://dusk.geo.orst.edu/oceans/PPT/PlateMotion.html here and here.
2. Convergent Boundaries – occur where plates move together. The denser plate will move under the less dense plate (subduction) and this usually results in volcanic activity (see Figure 1.16B, p. 24 text). A trench is usually formed where one plate moves under the other plate. See
http://dusk.geo.orst.edu/oceans/PPT/PlateMotion.html and here.
3. Transform Plates – occur where plates move laterally (grind past each other). The movement of these plates is often accompanied by earthquakes (see Figure 1.16C p. 25 text). See
http://dusk.geo.orst.edu/oceans/PPT/PlateMotion.html and here.
Do # 14, p. 29 text.
Read the Chapter Summary on p. 28 of the text.
Crossword
Read pp. 32-39 for next day.
