GEOL 2503 Introduction to Oceanography
Dr. David M. Bush
Department of Geosciences
University of West Georgia
POWERPOINT SLIDE SHOW NOTES
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Topic 2: Origins--The Universe, Solar System, Earth
Earth is 4.6 billion years old. Crust (Earth’s surface) just over 4, oldest fossils over 3.8
billion years old.
Diversification of life on Earth. Don’t worry about details. Note how recently major life
forms evolved.
Important ages
The nebular hypothesis for formation of our solar system
Another way to look at the nebular formation of our solar system
Early planet Earth
Differentiation of Earth interior
This is convection. Vertical motion driven by density. Warm at the bottom, cool at the
top.
Earth layers. Numbers are density values in grams per cubic centimeter (g/cm 3). Note
that water has a density of 1 g/cm3
Definition of density
Earth interior after differentiation with four major layers
How did the oceans form?
Natural time periods are very important
The year
Shape of Earth’s orbit around the sun
Seasons are caused by the tilt of Earth’s axis
Important seasonal sates
Lunar month
Solar day
Earth is very nearly a perfect sphere
How do we locate ourselves on the planet?
Earth’s Latitude and Longitude is simply a grid system
Latitude and longitude
Latitude
Latitude
Latitude can be used for distance measurement because lines of latitude are always
parallel, that means that everywhere on Earth they are always the same distance apart.
Lines of longitude are not parallel, so the distance between two lines of longitude varies
by latitude
Longitude
Longitude
Great circles and small circles
The Prime Meridian
Latitude and longitude of Carrollton, Georgia. Note the two different ways to express
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these: degrees-minutes-seconds and decimal degrees. Remember there are 60 minutes
in a degree and 60 seconds in a minute (this is not time, but angular measurement).
Example: a latitude of 1 degree 30 minutes (1°30’) can also be expressed as 1.5° ( 30
minutes is one-half of a degree).
Learn to identify these major coordinates (lines of latitude and/or longitude)
Longitude and time. Earth rotates 15° per hour. How long does it take to rotate one
degree?
Examples of longitude and time. Time around the world is set relative to Greenwich
Mean Time.
World time zones are based on the 15 degrees per hour rate of Earth’s rotation
Longitude, time, and Carrollton
More examples of longitude and time
John Harrison first realized the relationship between longitude and time and invented
the chronometer, a clock not only capable of measuring time accurately but also able to
work on rolling ships and under stressful conditions of temperature and humidity. Early
clocks were pendulum driven. Chronometers are spring and gear driven.
One of Harrison’s chronometers
Navigation is critical for travel, especially at sea where there are no landmarks
Radar
Loran
Global Positioning System
Satellites of the Global Positioning System
One of the GPS system’s NAVSTAR satellites
GPS navigation is real-time
Maps are critical for scientific exploration
Contour map
A contour map of a nearshore area
A physiographic map of the same area
Topographic maps
Topographic maps
Topographic map of Stone Mountain and vicinity
Topographic map of Jekyll Island
Topographic map of Carrollton.
A bathymetric map using contours
A bathymetric map using colors for different depth or elevation ranges
A physiographic map makes visualization of depth or elevation much easier. Refer back
to the contour and physiographic maps of the nearshore region.
A physiographic map of the world ocean also showing bathymetry with color
Nautical charts are used for navigation, they show safe sailing routes and hazards to
avoid.
Note how the navigation channels and the channel markers are clearly shown on this
nautical chart
Examples of nautical charts in the Caribbean area. Charts are available from the U. S.
National Oceanographic and Atmospheric Administration (noaa.gov).