GLG103 Geology in Public Issues
What will you learn in this course?
- Plate tectonics
- How different geologic hazards occur
- Human influenced and impacts of hazards
- Natural resources (water, metal, gas nuclear)
- Global climate change
Critical evaluation of news stories.
- Last Day to + Classes Sep 25
- Test 1: Oct 17
- Last Day to drop Nov 3
- Test 2 – Nov 21
Tests are worth 25%
Exam is worth 45%
Minute Reports 5% - Almost Participation Marks
How are humans agents of environmental change?
1. Japan – Huge measures taken before Tsunamis and earthquakes. Less death
toll, but all fail-safes…failed.
2. Thailand – No one educated, lack of safe infrastructure; big death toll.
3. New Orleans – Human engineering caused a natural disaster to become a
4. Famine in Somalia – Natural phenomenon of drought. Now however, issues
of overpopulation, lack of ability to migrate
5. Alberta Oil Sands - Heavy levels of containments in the Athabasca river.
September 14 th
Lecture 2: The Earth’s Structure and Composition
The Science of Geology
Geo “earth”, logos “discourse”
Geology, people & the environment
Relationships between people and the natural environment include Natural hazards, resources, world population growth & environmental
Some Historical notes about geology
Catastrophism: shaping of the Earth’s andscape by catastrophes.
Uniformitarianism “the present is the key to the past” – James Hutton,
became principle for modern geology
Both were right in some regards.
Exceedingly long time…the earth is 4.6 BILLION years old!
An appreciation for the magnitude of geologic time is important because
many processes are very gradual
Techniques give us fairly accurate ages of the earth
However, they are constantly being refined.
Formation of Earth’s Layered Structure
Chemical segregation early in the formation of Earth by gravity
-Core – inner layer, dense, iron rich
-Crust – solid thin outer layer
-Mantle – largest layer between core and crust composed of iron &
Layers defined by composition are four main ones.
- Lithosphere – rigid outer rind of Earth approx. 60-100km thick
Continental Lithosphere :silica rich- lower density
Oceanic lithosphere – thinner, but thicker density
Densities increase as you go further into the earth.
Plate Tectonics; Development of the Theory
- Continental Drift : 1912 Alfred Wegener
- Seafloor Spreading: 1960 Harry Hess
Evidence for Pangaea & Continental Drift
- Geometry of continent shorelines
- Matching ancient rocks & fossils
- Ancient ice-sheet glaciation
When magnetic north changes position, magnetic rocks point in direction of
magnetic north, changing direction.
Planet of Shifting Plates
- Plate Tectonics
- Lithospheric Plates move relative to one another at very slow rates
- Movement driven by convection in mantle Lithospheric Plate Boundaries:
Convergent, Divergent, & Transform
Divergent Boundaries – Spreading Zones
- Oceanic Spreading
Oceanic ridges (Mid Atlantic)
- Subduction Zones
Continent volcanic arc of strata volcanoes form from the heating of the subducting
plate and the melting of the overlying mantle and continental crust.
Continent-Continent Collision: not a lot of subduction ->Himalayas
The Rock Cycle
- Sedimentary Rock
Formed from sediments (sometimes call parent material)
Sediments created by
-erosion of any type of rock
-dissolved minerals creating precipitate
-accumulation of organic debris
Turned into rock(lithification)
-occurs due to
Compaction: when water is squeezed out of sediment
Cementation: minerals act as a glue which holds the rock together
The Rock Cycle
-Formed by solidification of molten material(magma)
- Can solidify above (extrusive) or below the earth’s surface (intrustive)
- INTRUSTIVE AND EXTRUSIVE ROCK NOTES FROM PPT
- The transfer of heat by circular movement of liquids or gases
- Convection can occur both above the earth (clouds) or below the earth
- Hotter rocks are less dense and rise; cooler rocks re more dense and fall due
- Any type of rock (igneous, sedimentary or metamorphic) modified by heat,
pressure and chemical processes
- Foliated metamorphic rocks show bands or layers
- Non foliated metamorphic rocks have a smoother appearance (e.g marble) - No melting of the rock occurs
- Rock is usually altered beneath the earth’s surface
- Contact metamorphism occurs when rock changes when in contact with hot
The Earth as a System
What Are Nutrients?
- Any chemical required for the proper functioning of an organism
C, H, P, S, Ca, Mg, K, O
- Products of one system are food for another (Feces-> Bacteria)
- Everything becomes recycled ideally.
The Carbon Cycle
- Large quantities are transferred from one compartment to another
- Stored in 4 spheres
- as molecules in organisms in biosphere
- as a gas in atmosphere
- as organic material, fossil fuels litho
- MISSING POINT PPT
Carbon is removed by photosynthesis
- approximately 110 billion metric tonnes/year
- returned by respiration of plants and animals
(50 billion metric tonnes) and decomposition (decay 60 billion tonnes)
This does not account for all C removed by photosynthesis. We are not 100
informed on Carbon Cycle
The Phosphorus Cycle
- found in rocks and minerals as phosphate
- typically bound in insoluble chemical precipitates
- unique in that it does not cycle through atmosphere
- does not have a gas phase
The Nitrogen Cycle
- Fixation: needs to be processed for organism to be used, usually by bacteria
and sometimes lightning strikes
- Assimilation: absorbed by organisms
- Mineralization/Ammonification: conversion of nitrate (expelled by
organisms) into ammonia by bacteria
- Nitrification: conversion of ammonia back to nitrate by bacteria
- Denitrification: Reduction of