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Lecture 8

EESA06 Lecture 8 Notes

Environmental Science
Course Code
Nick Eyles

of 3
Lecture 8:
Japan tsunami
Pacific plate separated by shallow water from Philippine plate
Tsunami radiates out towards the pacific
Japan moved 25 metres, direction is shown by vectors and distances seen by slip graph
It moved in one instance, because the plates are locked and built up of stress for a thousand years
Japan goes east and pacific plate underneath goes west
Slide 5 is the uplift/elevation of Japanese coastline, which killed people due to tilting up of ocean
floor/crust, water going west and shoreline got depressed
Geologic Time and Stratigraphy
THE EARTH IS 4.56 BILLION (4,560 000 000) YEARS OLD
How did we find this out?
1. EARLY IDEAS ON STRATIGRAPHY (the study of rock layers as in a book)
Strata; Greek for layer
Layers on slide 9, marine rocks, deposited way off shore under water, now several km
above land. Each layer may have a distinctive fossil type.
Correlate the rocks in one location with one from another location such as Canada and
Find the contemporary/ancient environment
Diluvium: meaning of a flood e.g. rocks. In eastern Canada. It deformed when Pangea
was beginning to come together because Africa was moving towards north America and
collided with the east coast
Creationist view of earth: created in an instant
Archbishop Ussher: looked at history about how long people lived. Interpretation of the
bible with the goal of getting the earths age. He believed earth was 6000 years old.
Earth was young.
Georgius Agricola: mining and saw layers and different strata. Questioned whether all
these strata were deposited at one time or has complicated history. Wrote his book in
1556; textbook for mining geologist. He realized the fossils are preserved ancient
oHerbert Hoover: president of the United States, the hoover dam, outside las
vagas. Translated the book.
Nicholas steno: he was a doctor, geologists did not exist. Father of stratigraphy
The Scottish enlightenment, industrial revolution. Energy source was coal for steam
engines, making steel.
Joseph black: chemist
James Hutton: interested in soil, father of modern day geology. He showed the periods
of erosions. Breaks are called unconformities, gaps in geological records.
Uniformitarianism or actualism: using the geological record to determine what has
happened in the past. Facies: Latin for appearance of.
Arthurs seat Slide 15, igneous intrusion, sill. Rocks had been formed in a molten state.
Rocks formed by magma rather than a flood
Lecture 16 sedimentary rocks intruded by igneous rock. Huttons rock
South of anbrea Lecture 18
Unconformity: gap slide 19
There were fossils in the secondary strata but not primary
Adam smith: founder of modern day economics, free trade
James watt: invented the steam engine
Walter Scott: he was a writer of Scotland.
Marmora: a giant hole in the ground that contain iron. First place when mining started.
Slide 22 limestones on top. Angular unconformity
The Taconic unconformity when Africa comes in contact with north America
Charles Lyell: wrote the first geology textbook and inspired Charles Darwin.
Louis Agassiz (Swiss): ice ages. 1km here and 3 in northern Quebec. He believed that ice
ages were to kill all living people for a new start
William Logan: Canadas first geologist 1844, identifies the origin of coal; decay of
ancient trees and became lithified
William Smith: made maps, canal. 1815 first geology map
1807 first geological society
1851 geological survey of India
Law of faunal succession: changes in the fossil types as we go upwards as evolution.
Using fossils to correlate. Disconformities: junior unconformity, small gap.
Volcanic ash: good for correlation because its deposited at the same time, same age
Dip: tilted where water will flow and that is the direction of dip such as dipping north
at 40 degrees
Strike: edge of harder layer of rock, cliff. The strike is 90 degrees to the dip
SLIDE 35 top left is dip
2. HOW LAYERS GET BENT & BROKEN (lost chapters)
Because of plate tectonic
Ripped out pages due to erosions
Where rocks get broker is called faults
San Andréas: Strike slip fault
Structural geology: how rocks are formed and the stresses. The purpose is to identify
ancient plate tectonic
Anticlines: where the rocks are arched
Syncline is where they form depression. A lot of oil and gas forms in anticlines
Thrust anticlines slide 37 bottom left
Cascade mountain: major thrust that turned the rocks upside down
Slide 39 flipped rock, youngest at the bottom
3. RELATIVE AGE OF ROCKS (this one is older than
Do fieldwork and by the nature of the relationship; lower is older
But because of tectonics, this order may be reversed
4. ABSOLUTE AGE (isotopic age dating; i.e 50 million)
This is NOT always possible
Radiometric age dating, 1913
We have unstable radioactive decay that break down and produce daughter elements
Uranium 238, with time, it breaks down to lead called uranium lead age dating which
can date back to billion years
Radiocarbon, half life of 5000 years
we can day back to 70, 000yrs
Zircons occur in igneous rocks and some metamorphic rocks. They have tree rings,
black circles where laser beams. It doesnt allow lead to escape; tight
5. THE GEOLOGIC TIMESCALE: 4.56 billion to today
Names of rock units around the world