EARTH121 Study Guide - Fall 2018, Comprehensive Midterm Notes - Unconformity, Time, Tectonics
12 Oct 2018
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EARTH121
MIDTERM EXAM
STUDY GUIDE
Fall 2018
EARTH 121
Introduction
How do we determine the age
1) Relative ages: based upon order of formation
2) Numerical ages: Actual number of years since the actual event
Plate Tectonics
1. Nicholas Steno: Relative age (Qualitative method)
2. James Hutton(quantitative)
3. Sir William Logan
4. J.Tuzo Wilson
Eaths Laeed Stutue
1) Lithosphere: outermost layer; crust and upper mantle
- Important in plate tectonics due to temperature and pressure
- What makes up the tectonic plates
2) Asthenosphere: below the lithosphere, upper mantle below the lithosphere
Plate tectonic explains:
- Distribution of earthquakes and volcanoes
- Changes in past positions of continents and ocean basins
- The origins of mountain belts and seamount chains
- The origin and ages of ocean basins
Alfred Wegner: PANGEA; land masses slowly move-> continental drift
Evidence of continental drift: fossils, mountain ranges, continent
Sea-floor Bathymetry: eco sounding sonar allowed rapid sea floor mapping from ships crossing
the oceans
The ocean floor: discoveries
1. Mountain range runs through every ocean
2. Deep ocean trenches occur near volcanic island chains
3. Submarine volcanoes poke up from the ocean floor
4. Huge fracture zones segment the mid-ocean ridge
1960: Scientific revolution
Harry Hess: sea floor spreading
- Upwelling magma erupts at mid ocean ridges
- New crust moves away
- Sea floor sinks back into the mantle
Sea floor spreading= continents move apart
Sea flood sinking into mantle= continents move together
Evidence of sea-floor spreading: 1963 Lawrence Morely, Fred Vine, Mathews
Magnetic Strips in the ocean crust near ridges: geomatics reversals
- Rock of the ocean floor contains iron
- ‘ok ooled ad hadeed ad lied to the eaths ageti poles
- Width of the strips
o Faster spreading= wide strips
o Slower spreading=narrow stripes
find more resources at oneclass.com
find more resources at oneclass.com
EARTH 121
1960 Tuzo Wilson discovered Transform Faults
- Connect ocean ridge and divide lithosphere into ridge system
- Continental drift theory became theory of plate techtonics
What drive plate motion?
- Too complex
- Convection occurs (not prime driving mech.)
Slab-pull: gravity pulls a subducting plate downward
Ridge-push: elevated MOR pushes lithosphere away
Tectonic plate boundaries: outermost shell of earth consists of a mosaic rigid plates that have
been moving relative to one another millions of years.
Minerals
Atom: The smallest particle that exists in an element
Compound: A substance formed by the chemical combustion of 2+ elements in definite
proportions and usually having properties different from those its constituent elements
Mineral: natural occurring, inorganic crystalline soild material with a specific chemical
composition and internal structure
Rock: A consolidated mixture of minerals
Lithospheric plate: rigid outermost layer of earth including crust and upper mantle. Above
asthenosphere
Earth’s crust: The very thin outermost layer of Earth
Silicon: Non-metallic element with atomic number 14, SI chemical symbol, present in sand and
glass (used for electronics)
Silica: compound which its crystalline form is mineral quartz
Silicate: any mineral that contains elements silicon and oxygen bonded together
- Most rock forming minerals
Most common:
Olivine: isolated silicon, no cleavge
Pyroxene: single chain, two
Amphibole: double chain, two
Mica/clay group: Sheet silicate
Quartz: framework silicate, none
Mineral is
1. Naturally occurring
2. Inorganic
3. Solid
4. Ordered internal molecular structure
5. Definite chemical composition
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
How do we determine the age: relative ages: based upon order of formation, numerical ages: actual number of years since the actual event. Plate tectonics: nicholas steno: relative age (qualitative method, james hutton(quantitative, sir william logan, j. tuzo wilson. Important in plate tectonics due to temperature and pressure: lithosphere: outermost layer; crust and upper mantle. What makes up the tectonic plates: asthenosphere: below the lithosphere, upper mantle below the lithosphere. Changes in past positions of continents and ocean basins. The origins of mountain belts and seamount chains. The origin and ages of ocean basins. Alfred wegner: pangea; land masses slowly move-> continental drift. Evidence of continental drift: fossils, mountain ranges, continent. Sea-floor bathymetry: eco sounding sonar allowed rapid sea floor mapping from ships crossing the oceans. The ocean floor: discoveries: mountain range runs through every ocean, deep ocean trenches occur near volcanic island chains, submarine volcanoes poke up from the ocean floor, huge fracture zones segment the mid-ocean ridge.
