Textbook Notes (362,789)
Canada (158,053)
EESA06H3 (234)
Nick Eyles (205)
Chapter 2

Chapter 2 notes

15 Pages
Unlock Document

University of Toronto Scarborough
Environmental Science
Nick Eyles

Chapter 2 What is plate tectonics? Tectonics is the study of the origin and arrangement of the broad structural features of the Earths surface which includes folds, faults, mountain belts, continents and earthquake belts. Plate Tectonic is a theory that the Earths surface is divided into large few thick plates that change position and size. Intense geologic activity occurs at plate boundaries where plates move away from one another, past one another or toward one another. Plate tectonic theory helps explain earthquake distribution, the origin of mountain belts, the origin of sea-floor topography, the distribution and composition of volcanoes and etc. This concept was developed in late 1960s by combining two-pre-existing ideas of continental drift and sea-floor spreading. Continental drift is the idea that continents move freely over the Earths surface, changing their positions relative to one another. Sea-floor spreading is a hypothesis that the sea floor forms at the crest of mid- oceanic ridges, then moves horizontally away from the ridge crest toward an oceanic trench. How did the Plate tectonics theory develop? The early case for Continental drift Continents can be made to fit together like pieces of jigsaw puzzle. In the early 1900s Alfred Wegner, a German meteorologist made a strong case to support continental drift. He noted that South America, Africa, India, Antarctica and Australia had almost identical late Palaeozoic rocks and fossils. The plant Glossopteris is found in Pennsylvanian and Permian-age rock on all five continents, and fossil remains if Mesosaurus, a freshwater reptile, is found in Permian-age rocks only in Brazil and South Africa. www.notesolution.com Also, fossil remains of land-dwelling reptiles Lysotrosaurus and Cynognathus are found in Triassic-age rocks on all 5 continents. Wegner proposed that all continents were once assembled together as a super continent called Pangaea. Pangaea initially separated into two parts; Laurasia was the northern supercontinent, containing the present day North America and Euraisa (excluding India). Gondwanaland was the southern supercontinent, composed of all the present day southern hemisphere continents and India. Wegner also began studying ancient climates (Paleoclimatology). He found out that glacial features indicate a cold climate near the North Pole or South Pole. Coral reefs indicate warm water near the equator. Crossbedded sandstones can indicate ancient deserts near 30 degrees North and 30 degrees South latitude. Skepticism about Continental drift Wegners idea was not clear-cut since he had no mechanism to account for continental drift Wegner proposed that continents ploughed through the oceanic crust. Most geologists disagreed and thought it violated what was known about the strength of rocks at the time. The driving mechanism proposed by Wegner for continental drift was a combination of centrifugal force from the Earths rotation and the gravitational forces that cause tides. However, calculations showed that these forces were too small to move continents. Therefore, because of this little attention was given to Wegners ideas in the northern Hemisphere including North America. Work completed in 190s and 1950s set the stage for the revival of the idea of continental drift along with new ideas about sea-floor spreading, into the concept of plate tectonics. Investigations were conducted in the two areas: (1) study of the sea floor and (2) geophysical research, especially in relation to rock magnetism. Study of the Sea floor www.notesolution.com
More Less

Related notes for EESA06H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.