ESCI111: Introduction to Physical Geology & Physical Geography Dr. Francis O. Odemerho Alumni Hall, Room 1402 Tel: (618) 650-2097 Email: [email protected]@siue.edu

ESCI111: Introduction to Physical Geology ESCI111: Introduction to Physical Geology & Physical Geography& Physical Geography

Dr. Francis O. Odemerho Alumni Hall, Room 1402

Tel: (618) 650-2097Email: [email protected]

Website: http://www.siue.edu/~fodemer/esc111.htm

Topic 1: Introduction to Physical Topic 1: Introduction to Physical GeologyGeology

INTRODUCTION- The Science of Geology and Scope of Physical Geology - Importance of Physical Geology - Geologic Systems

SOME HISTORICAL NOTES ABOUT GEOLOGY - Catastrophism- Uniformitarianism

EARTH AS A PLANET- The Solar System - Terrestrial Planets - Unique Features of Planet Earth - Spheres of the Planet Earth - Earth’s Moon

The science & Scope of Physical GeologyThe science & Scope of Physical Geology

Geology is the scientific discourse of planet Earth

It is divided into 2 broad areas:Physical Geology:

- examines the materials making the earth - and geologic processes operating on or

beneath the earth surfaceHistorical Geology:

- chronology of geologic events - focuses on asking the when questions

Geology Sub-fieldsGeology Sub-fieldsPlanetary Geology Tectonics

Geomorphology Paleontology

Seismology Paleogeography

Geophysics Stratigraphy

Oceanography/Ocean Science Geochronology

Environmental Geology Archeological Geology

Economic Geology Biogeosciences

Petrology Engineering Geology

Geochemistry Forensic Geology

Mineralogy History of Geology

Structural Geology Hydrogeology

Glacial Geology Medical Geology

GEOLOGY: Subfields and Related DisciplinesGEOLOGY: Subfields and Related Disciplines

The Two Broad Fields of GeologyThe Two Broad Fields of Geology

Physical Geology Historical GeologyGeomorphology Paleontology

Seismology Paleogeography

Geophysics Stratigraphy*

Oceanography Geochronology

Environmental Geology

Economic Geology

Petrology

Geochemistry

Mineralogy

Structural Geology

Glacial Geology

Importance of Physical GeologyImportance of Physical Geology

Meets SIUE general education requirement

Helps our understanding of nature and how the earth works

Helps us in the discovery of earth’s natural resources:

- water and soil resources- mineral ores and deposits

- building materials - oil fields for fossil fuels (Petroleum, Coal and Natural Gas), etc, etc

Importance of Physical GeologyImportance of Physical Geology

Offers us key information on the causes and effects of past climatic changes

Increases our environmental awareness and the recognition of potential geologic hazard zones

Serves as useful guide in planning construction works, environmental planning and management

Some Historical Notes About GeologySome Historical Notes About Geology

Writings about earth’s materials and processes started more than 2300 years ago, among Greco-Roman scholars

Aristotle believed that: - rocks were created under the influence of stars- earthquakes are caused by over-pressured

ground air that escaped rapidly when heated up central fires

Aristotle’s authoritative posture thwarted the growth of geologic sciences


School of Catastrophism:- Archbishop James Ussher in the mid-1600 claimed that the earth was created in 4004 B.C.

- This means that the earth is only 6000 years old

- This meant that all geologic structures were formed very rapidly within the last 6000 years rather than millions of years expected by geologists

- Such short earth history gave rise to the school of catastrophism that dominated geology during the 17th and 18th centuries


- Catastrophists believe:

=> that landforms are produced by greatcatastrophic events that are no longer in operation today

=> that features such as mountains and canyons were produced by sudden and often

worldwide disasters like the Noah’s flood

=> in divine intervention and creationism in geology


School of Uniformitarianism:- is to counter the teachings of the school of catastrophism by James Hutton in his book “Theory of the Earth” in the late 1700s

- He argued that the Earth has a long history withno vestige of a beginning & no prospect of an

end


- He argued that physical, chemical & biological laws that operate today also operated in the past (i.e. the present is the key to the past)

- And that landforms are produced by geologic processes that act slowly and steadily (or uniformly) through time

John Playfair and Charles Lyell made the doctrine of uniformitarianism to be accepted by the scientific community and helped to remove religion from geology


The Exploration of American West in the mid-1800s laid the foundation for the development of modern geology

Geologic TimeGeologic Time

Geologic time scale is developed using two basic methods:- Relative Dating Technique and- Absolute (Radiometric) Dating Technique

Relative dating involves the placement of rocks in their proper sequence of formation without knowing their actual age in years using simple rules like the principle of:- superposition- fossil succession- original horizontality and cross-cutting

Geologic TimeGeologic Time

Geologic TimeGeologic Time Based on relative dating techniques geologists worldwide

built the standard geologic column of earth history

The Geologic time scale is divided into two major Eons:

- Phanerozoic Eon (0 – 542 million years ago)

- Precambrian Eon (542million – 4.5 billion years ago):

- Proterozoic (542million - 2500million years ago)(First Multi-celled organisms)

- Achaean (2500million – 4000million yrs ago)(First One-celled organisms)

- Hadean (4000million – 4500 million years ago) (First One-celled organisms)

Geologic TimeGeologic Time The Phanerozoic Eon of time is divided into three major

Eras:

- Cenozoic Era- Mesozoic Era- Paleozoic Era

The Precambrian Era accounts for 88% of geologic time

Absolute dating determines the actual age of rocks using radiometric methods

The Earth is about 4.5 billion years old

The Nature of Scientific InquiryThe Nature of Scientific Inquiry

Science is based on the assumption that nature is orderly, consistent and predictable

Therefore, the goal of science is to:- discover the underlying pattern in nature- make general verifiable statements of relationships in nature - make predictions about what to or not to expect about nature

To achieve this goal, scientists make observations and collect measurable facts that help to explain any observable relationships in nature


How and why things happen is explained using:- hypothesis which is a tentative or untested

explanations

- theory which is a well tested and widely accepted view that the scientific community agrees best explains certain observable facts

Hence, the scientific method involves:- the formulation of some form of hypothesis- the collection of data through observation and measurement


- testing the data through some form of analysis to see if the data support the initial hypothesis

Some scientific discoveries may occur through logical reasoning alone

Once an hypothesis survives extensive scrutiny, it is elevated to the status of a theory

Paradigm – a theory that is held with a very high degree of confidence because it explains a large number of interrelated aspects of the natural world

Geologic SystemsGeologic Systems

The earth is a natural system in continuous motion

Geologic systems governed by natural laws make us to understanding how planet earth works

Hydrologic system and tectonic system are examples of geologic systems that help us to understand:- geologic change and their effects- geologic processes- structural features of our planets


A system is a set of interdependent objects or materials that work together with energy as a unit or a unified whole

A system helps us to understand how rainfall, runoff, landforms are related and function together as a unit

Natural systems are of two types:- Closed system (exchanges only heat, no new

matter) (Example: cooling lava flow)- Open system (exchanges both heat and materials)


Most geologic systems are open systems because energy and matter flow freely across system’s boundaries (Example: river system with rainfall from outside)

The river system receives matter like rain & snow from outside the system (input) and flows out of the system to the ocean (output)

It utilizes gravitational energy and kinetic energy and solar energy from the sun

Geologic Systems Geologic Systems

In general, geologic systems involve the flow of energy and the movement of matter

The transfer of matter and energy causes the system to change in order to establish a state of Equilibrium with the new surroundings

Some examples of subsystems of the geologic systems include:- The Hydrologic System- The Tectonic System, etc

The Hydrologic SystemThe Hydrologic System

It is a geologic system showing the pathways of water moving from:- the oceans- to the atmosphere- over the continents, and- back to the oceans

The flow of water across earth surface causes erosion, transport and deposition of sediments

Major subsystems include:- Atmosphere-Ocean system, River systems- Glacial systems, Groundwater systems- Shoreline systems and Eolian (wind) systems

The Hydrological CycleThe Hydrological Cycle

The Hydrological CycleThe Hydrological Cycle

The Solar SystemThe Solar System

The Solar System Consists of:The sun (center of the solar system) and eight planets

Four inner planets of the solar system are called terrestrial planets: (Mercury, Venus, Earth and Mars)

The Solar SystemThe Solar System

The Solar System Consists of:

>10,000 asteroids (asteroid belt between Mars and Jupiter)

An Asteroid With Impact CratersAn Asteroid With Impact Craters

The Solar SystemThe Solar SystemThe Solar System Consists of:meteorites (pieces of rocks and minerals frozen in

gases)

Hale-Bopp Comet seen (1997) with long glowing tail due to ice vaporization

The Solar SystemThe Solar SystemThe Solar System Consists of:natural satellites or moons (>64 moons)

all the planets formed same time from same general materials and move counterclockwise in an elliptical orbit around the sun

Solar Systems Solar Systems

Pluto is no longer regarded as a planet of the solar system


Pluto is not part of our solar system because of:

- its unique oblique orbital plane and

- its relatively higher density, given its location


This is the current composition of the solar system

All planets orbit in the same plane as the sun’s equator


The Nebula theory is the most accepted explanation of how the solar system is formed

According to the Nebular hypothesis:

- solar system evolved from rotating cloud of dust and gases called nebula

- nebula contained mainly hydrogen and helium produced by the Big Bang

- nebula began to contract at about 5 billion yrs ago



- nebula became flat and disk-shaped with the protosun at the center

- inner planets began to develop from condensed

rocky and metallic clumps with high melting point

- strong solar winds removed the lighter gases like hydrogen and helium from the inner planets



- larger outer planets began to form from the lighter gases with a high percentage of ices or frozen gases – water, carbon dioxide, ammonia, and methane

Glowing nebular clouds of gases and dust particles become concentrated to form stars

Gravitational collapse of nebula causing its inward contraction

Nebula contracted into a rotating disk and heated up as gravitational energy converts into heat energy

Cooling nebula condenses to form tiny rocky and metallic solid particles

Collision of dust-size particles join to form asteroids and accrete to form the planets

Features of Terrestrial PlanetsFeatures of Terrestrial Planets

Terrestrial planets: Mercury, Venus, Earth & Mars

Composed of minerals and rocky materials

more dense (>3gm/cm3)

Less oblate in shape (more nearly spherical)

Slower in rotation and Smaller in size

Diverse and shallow atmosphere

Common Features of The PlanetsCommon Features of The PlanetsPlanets Rotation Time

(Days)

Equatorial Diameter (km)

Mean Density

(g/sq. cm)

TERRESTRIAL PLANETS

Mercury 58.7 4,880 5.43

Venus 243 12,104 5.24

Earth 1 12,760 5.52

Mars 1.03 6,787 3.98

JOVIAN PLANETS

Jupiter 0.41 142,796 1.33

Saturn 0.43 120,660 0.69

Uranus 0.72 51,200 1.27

Neptune 0.67 49,500 1.76OTHER PLANETS

Pluto 6.39 2,300 2.03

Features of Jovian PlanetsFeatures of Jovian Planets

consist of: Jupiter, Saturn, Uranus Neptune

much larger in size

composed entirely of gases and less dense

much more oblate and rotate more rapidly

dense and turbulent atmospheres

Unique Features of Planet EarthUnique Features of Planet Earth

organized into four spheres: (atmosphere, hydrosphere, biosphere and lithosphere)

appropriate temperature for water to exist as solid, gas and liquid

biosphere and hydrosphere unique to earth

Unique Features of Planet EarthUnique Features of Planet Earth

earth’s surface is dynamic (continuously changing) because of:

- movement of materials powered by highinternal heat

- movement of surface water and windspowered by solar energy

atmosphere is 78% nitrogen and 21% oxygen

Earth’s Atmosphere ComparedEarth’s Atmosphere Compared

Earth’s AtmosphereEarth’s AtmosphereIt is the envelope of gases held in place by

gravity

Dominant gases by volume of dry air:- Nitrogen (78%)- Oxygen (21%) (no in earliest atmosphere)- Argon (0.93%)- Carbon Dioxide (0.03%)

(used to be more but reduced due to the formation of limestone in the oceans)- water vapor (0-4%)

It extends up to 6000 miles but 97% of atmospheric gases found within 18 miles

The Planet EarthThe Planet Earth

Earth’s Atmosphere ContinuedEarth’s Atmosphere ContinuedThermal layers of the atmosphere

- Troposphere (0-13 km) (weather belt)- Stratosphere (13-55 km) (ozone layer)- Mesosphere (55-80 km)- Thermosphere (80-210 km)- Exosphere (>210 km)

Most weather phenomena occur in troposphereThe major wind systems of planet earth are:

Lat 0o – lat 30o Trade Wind Belt

Lat 30o – lat 60o Westerly Wind BeltLat 60o – lat 90o Polar Easterly Wind Belt

Thermal Layers of Earth’s AtmosphereThermal Layers of Earth’s Atmosphere

Earth’s HydrosphereEarth’s HydrosphereAll water bodies including:

- ocean water 97%- Ice/glacier 2.15%- Groundwater 0.62%- Saline lakes & inland seas 0.008%- Freshwater (lakes & streams) 0.009%- 71% of earth surface is water

Evolution of life is because of the presence of water

Water moves from ocean-atmosphere-land-ocean to form the hydrological cycle

Sequence of operation of the cycle involves: evaporation-condensation (cloud formation)-precipitation-runoff

Earth’s Hydrosphere ContinuedEarth’s Hydrosphere Continued

Hydrological cycle is powered by solar energyGlacier locks up water on land and breaks the

cycleComponents of the hydrological cycle:

- River systems: collect surface runoff and groundwater, hence stream valleys are the most abundant landform on earth

- Groundwater systems: water moving slowly through pore spaces and capable of dissolves soluble rocks to form caverns in Karst regions of Monroe County in Illinois and Mammoth Cave in Kentucky

Earth’s Hydrosphere continuedEarth’s Hydrosphere continued

- Glacier systems: Pleistocene glacier occurred covered much of North America and Europe with ice sheets about 15,00 years ago.

Antarctica Continental glacier is 2.0-2.5 Km thick and covers 13 million Sq. Km. Today, 2% of earth’s total water is glacier

- Shoreline systems: areas affected by wave action and produce wave-cut cliffs,

terraces, delta, beaches, bars, and lagoons.

- Wind systems:

Earth’s BiosphereEarth’s Biosphere

The world of all plants and animals 1.75 million species already described >13 million species estimated Today’s species represent only 10% of species that

ever lived 15-20% of all species would be extinct by the

beginning of the 21st century Marine organisms form exoskeletons and shells from

seawater They also form fossil fuels and beds of limestone Preserved as fossils and help to reveal earth history

GeosphereGeosphere

The geosphere is the solid earth extending from the surface to the center of the planet (about 6400km)

Its outermost solid layer is called the lithosphere and about 70-100 km thick

It is broken into lithospheric plates made up of seven major plates and about a dozen minor plates

lithospheric plates moved by convection currents

Earth’s Lithospheric PlatesEarth’s Lithospheric Plates

Earth’s Lithospheric PlatesEarth’s Lithospheric Plates

Earth’s MoonEarth’s Moon

No atmosphere, No hydrosphere, No biosphere

Densely cratered highlands called Terrae

Lava plains called Maria (fewer craters) is basalt

Craters formed 4.5 billion years ago but still undeformed



Lunar geologic history:

- initial period of intense meteorite bombardment

- period of volcanic activity

- later period of light meteorite bombardment

- undeformed by internal forces

- undeformed by wind, water, and glacier


Luna Time ScaleLuna Time Scale

Review Questions (Topic 1)Review Questions (Topic 1)

1. What are the basic differences between the disciplines of physical and historical geology?A. Physical geology is the study of fossils and sequences of rock strata; historical geology is the study of how rocks and minerals

were used in the pastB. Historical geology involves the study of rock strata, fossils, and geologic events, utilizing the geologic time scale as a reference; physical geology includes the study of how rocks form and of how erosion shapes the land surfaceC. Physical geology involves the study of rock strata, fossils, and deposition in relation to plate movement in the geologic past; historical geology charts how and where the plates were moving in the pastD. None of the above – physical geology and historical geology

are essentially the same


2. Compared to the age of Earth accepted as correct today, how did 17 th and 19th century proponents of catastrophism envision the Earth’s age?

A. They believed Earth to be much older than current estimates B. They believe it to be about the same as current estimates, give or take a few million years C. They believed Earth to be much younger than current estimates D. None of the above – they didn’t really address the age of Earth

3. ________ was an important 18th century English geologist and proponent of uniformitarianism. A. Charles Lyell B. Isaac Newton C. James Hutton D. James Ussher

4. The currently accepted age of Earth is ______ years. A. 4.5 thousand B. 6.1 trillion C. 4.5 billion D. 6.4 million

5. The ____ division of the geologic time scale is an era of the phanerozoic eon.

A. Paleocene B. Paleozoic C. Permian C. Proterozoic


6. The ____ forms the relatively cool, brittle plates of plate tectonics. A. Asthenosphere B. Lithosphere C. Eosphere

D. Astrosphere

7. All of the following are possible steps of scientific investigation except for _____. A. The collection of scientific facts through observation and measurement B. Assumption of conclusions without prior experimentation or observation C. The development of one or more working hypotheses or models to explain facts D. Development of observations and experiments to test the hypothesis

8. The ____ refers to the total of all life on Earth. A. Hydrosphere B. Atmosphere C. biosphere D. asthenosphere


9. A ____ system is one in which energy moves freely in and out, but no matter enters or leaves the system. A. Closed B. Open C. Feedback D. Equilibrated

10. _______ is often paraphrased as “The present is the key to the past.” A. Biblical prophesy B. Uniformitarianism C. Catastrophism D. Aristotelian logic

11. ______, a popular natural philosophy of the 17th and early 18th centuries, was based on a firm belief in a very short geologic history for Earth. A. Ecospherism B. Exoschism C. Uniformitarianism

D. Catastrophism

12. The ________ proposes that the bodies of our solar system formed at essentially the same time from a rotating cloud of gases and dust. A. Big Bang theory B. Plate tectonics C. Nebula hypothesis

D. Heliocentric theory


13. The doctrine of uniformitarianism implies that the current forces and processes shaping the earth have been operating for a very long time. A. True B. False

14. The currently accepted age of Earth is approximately 4.5 million years. A. True B. False

15. A scientific theory is a tentative or untested explanation that is proposed to explain scientific observations. A. True B. False

16. In an open system both energy and matter flow into and out of the system. A. True B. False

17. According to the nebular hypothesis, all the bodies in the universe

evolved from a rotating cloud of gases and dust about 5 billion

years agoA. True B. False

Documents

ESCI111: Introduction to Physical Geology & Physical Geography Dr. Francis O. Odemerho Alumni Hall, Room 1402 Tel: (618) 650-2097 Email: [email protected]@siue.edu