EESA06 Lecture 8 Notes
•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 earth’s 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.
•Arthur’s 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. Hutton’s 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: Canada’s 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 Andréa’s: 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 doesn’t allow lead to escape; tight
5. THE GEOLOGIC TIMESCALE: 4.56 billion to today
•Names of rock units around the world