Class Notes (836,591)
Canada (509,862)
ESS102H1 (104)
C.Banks (29)

October 26.docx

10 Pages
Unlock Document

Earth Sciences

October 26 Expanding Earth versus Sea-Floor Spreading - traits of “critical thinking” and characteristics of a good scientist: o reasonable scepticism towards ideas o being open to reconsider one’s position o trust in reason, judgement not based on emotion - today look at a controversy using papers written by two very prominent proponents of plate tectonics 1. Expanding Earth o Tuzo Wilson 1908-1993)  first geophysics undergrad in Canada  worked at the Geological Survey  Physics Professors at UofT (1946-1974)  founder of Science North in Sudbury  first non-American president of AGU (AGU altered its constitution to allow this)  in a 1960 paper Wilson argued in favour of “Expanding Earth” • “...the foregoing hypothesis has the merit of appearing to explain many features of the Earth’s surface, though this does not constitute a proof.”  Wilson’s arguments: 1. Two possible causes for Earth’s expansion  decrease of gravitational constant  phase changes within Earth, and/or differentiation of core and mantle 2. Effect  circumference increased by 1,100 miles  average rate of 0.5 mm/year 3. Only mid-ocean ridges (not complete ocean basins) have grown throughout geologic time  matching observations/consequences • high-heat flow at mid-ocean ridges (MOR) • shallow earthquakes at MOR • buckling of Earth away from MOR (distance to MOR may be necessary condition) • J-shape of MOR and continents may show initial fracturing • some drift of continents possible but polar wander due to changing moment of inertia  facts/explanations in Wilson’s paper • mechanism: • ocean ridges: • high heat flow at ridges: • fit of continents: • mountain building: • polar wandering: • objection to Wegener’s “plowing” continents: • youth of ocean basins 2. Sea-Floor Spreading
More Less

Related notes for ESS102H1

Log In


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.