THE UNIVERSITY
OF WESTERN ONTARIO
LONDON CANADA
Final
Examination - Summer Term 2003
Time: 3 hours Earth Sciences 240A
Distance Studies
(No electronic materials permitted)
PART A
Answer ONE of the
following three questions. Each question is valued at 20 marks.
Each question may be answered in as little as two pages of
single spaced (essay format) writing (if you prefer double spaced answers, do
the math!). Obviously, you may use as little space as you wish, but each topic
must be fully discussed in whatever space you use. Please do not use point-form
answers except where a listing is appropriate within an essay answer. Use
illustrations to strengthen/support discussions, but not in substitution for
words.
- Meteor
Crater in Arizona was
discovered a long time ago, but was not acknowledged to be the product of
impact until relatively recently. Based upon (a) the knowledge you now
have of that crater, the area around it, and the character of the
meteoroid that produced it; and (b) your current excellent knowledge of
impact objects and their effects, discuss how you would identify and fully define such a feature if you
stumbled across an identical one today
in, say, Canada’s Northwest Territories.
- You
have been mapping a continuous sequence of horizontally stratified marine
sedimentary rocks. From the bottom of the sequence up, there has been an
abundance of hard-shelled fossils, but at one very well defined horizon
they nearly all disappear! The rocks immediately above that horizon have
almost no fossils, but progressively higher layers in the sequence
gradually contain more and more fossils. Describe in detail what you would
do to determine if this is evidence of a previously undiscovered mass
extinction event.
- In
Mid-Cretaceous times, only about 12% of the globe was dry land, thus seas
were abundant. Seas were relatively warm and all life –especially marine
life – was thriving. At the end of Cretaceous there was a terrific mass
extinction of all life, terrestrial and marine. At just about this time, India
was situated over a mantle plume (creating a dramatic hot spot) and the
Deccan Traps were erupted. No matter what you (or I) might think about an
impact cause for the mass extinction, a host of scientists still believe
it was caused (totally) by the Deccan Trap eruptions. Your task is to
critically review the hard evidence collected from the geologic record,
and convince that host of scientists that they are wrong.
PART B
Fill in the missing word(s). Please put your answers, in
sequential order, in the answer booklet – NOT on this examination sheet. Each
question is valued at 1 mark.
- Carbon
isotope age dating is useful only for C-containing items less than
___________ (number) years of age.
- Products
of early supernovae are part of your personal composition.
________(True/False)
- ___________
is known as the ‘Father of Catastrophism’.
- Earth
should expect one Zhamanshin-size asteroid to
impact every _________ years.
- In
determining the kinetic energy of a meteoroid, the most important factor
is __________________.
- The
average life span of any species is about ___________ (number) million
years.
- The
southern block of Pangaea was called __________________.
- When
there is a slow but continuous movement of both sides (relatively) of a
fault, the motion is called _______________.
- A
compression seismic body wave travels at roughly ____________ km/s.
- In the
case of volcanic activity, the heat of _______ is overwhelmingly more
important than any other source.
- Magma
classified as MORB is most likely found in ____________ (geographic
location).
- One of
the two most abundant dissolved volatiles in magma is ___________.
- The
only flood basalt with which humans have any experience erupted at
_____________ (location and country).
- Stothers and Rampino
postulated a periodicity of approximately ____ (number) million years for
plateau basalt eruptions, magnetic field reversals and mass extinctions.
- The
action of water, together with ____________ from the atmosphere is largely
responsible for production of caves in limestone.
- Underground
caves, stranded in the zone of aeration above a dropping water table, may
lead to large circular depressions called ________________.
- All
other things being equal, air density is lowest on a ______ (hot
or cold) day.
- The
most mass of the atmosphere is in the _____________ zone.
- The
percentage of incoming radiation that is reflected by a natural surface is
called _____________.
- Mount
St. Helens erupted in 1980, emitting approximately _________
cubic kilometers of material from its magma chamber.
PART C
Answer any 3 of the following 5 questions. Each question is
valued at 10 marks.
- (a)
Earliest Earth had a greenhouse atmosphere loaded with CO2.
Explain why that changed and where the CO2 went. [7]
(b) If major volcanic eruptions
occurred nearly every year for a century, what might happen to global climate? [3]
- (a) Define
latent heat. [4]
(b) Explain the sequence of events
that turns an African storm into a hurricane hitting the east coast of North
America. [6]
- Sketch
a map of an idealized tectonic plate and evaluate the volcanic hazards
along each type of plate edge. [10]
- Explain
how hot mantle rock can melt from (i) changes in
temperature, (ii) changes in pressure, (iii) water content. [10]
- (a)
Explain three ways that humans have caused or triggered earthquakes. [6]
(b) What type of fault motion best
characterizes the “Basin and Range” area of the western US
states in this century? [1]
(c) What Hawaiian volcanic
processes cause earthquakes. [3]
PART D
Write complete definitions of each of the following; use
point form if you wish. Each question is valued at 3 marks.
- Supercell
- Kinetic
energy
- Radioactivity
- Strain
- Farallon
Plate
- Rodinia
- Aerolites
- Tektites
- Supernova
- Unconformity