‘SIDE VIEW’

‘TOP VIEW’Solar System on outsideof Orion Arm (25,000 light years from centre)

100,000 ly

Nebula (dust cloud) hypothesis

Basis: observations of other systems

1. Collision or dying star in Milky Way? exploded2. Nebula (cloud of dust and gas) results3. H and He condense into Sun4. Disk of matter (many elements) around sun5. Disk slowly accretes into clumps

(planetesimals)6. planetesimals planetoids planets

(including Earth) and satellites

Eons, Eras, Periods and EpochsSuperposition: youngest rocks superimposed on older rocks “Relative time”

Dating by radioactive isotopesHalf-life: time for ½ of unstable isotopes to decay “Absolute time”

Uniformitarianism:“The same physical processes active in the environment today have been operating throughout geologic time” Hutton (1795), Lyell (1830)

Source: University of Calgary

Red ovalsindicatemajorextinctionevents

The Earth incross-section

Upper mantleand lithosphere

Mountain massesdisplace mantle material

Isostatic adjustmentdue to loss of massby erosion

Deformation fromsediment load

ISOSTASYElevation of tectonic plates determined by density/thickness

MineralA natural, inorganic compound with a specific chemical formula and a crystalline structure

Examplessilicates (quartz, feldspar, clay minerals), oxides (eg., hematite) carbonates (eg., calcite)

An assemblage of minerals bound together

• Igneous (solidify & crystallize from molten magma)

• Sedimentary (settling & cementation)

• Metamorphic (altered under pressure)

• from magma (molten rock beneath the surface)

• intrusive or extrusive (from lava)

Laccolith

Dike

Sill

Batholith

plutons

Existing rock or organic material is digested by weathering, picked up by erosion, moved by transportation, and deposited at river, beach and ocean sites.

Lithification follows (cementation, compaction and hardening)

Laid down in horizontally-layered beds

Conglomerate largest clastsSandstone sand cemented

togetherSiltstone derived from siltShale mud/clay compacted into

rock

Limestone calcium carbonate, bones and shells cemented or precipitated in ocean

watersCoal ancient plant remains

compacted into rock

note the shells

Any type of rock is transformed, under pressure and increased temperature

Harder and resistant to weathering

Produced from any rock type by:•Compressional forces due to plate collisions•Regional and contact metamorphism

Shale Slate

Granite Gneiss

Basalt Schist

Limestone, dolomite Marble

Sandstone Quartzite

Crustal Movements

•Continents are adrift due to convection currents in the asthenosphere

•Mantle movements result in platemigration

•225 M BP: Pangaea

Continents Adrift

Age of mid-oceanic ridge magnetic stripes

Subduction zones

“Ring of fire”

Age and thickness of oceanic crust

Fossil Record (plant and animal)

Distribution of marsupials vs. placentals

Mid-oceanic ridge magnetic stripes

See: http://www.scotese.com/sfsanim.htm (animation)

Divergent Boundaries (constructional)

Convergent Boundaries (destructional)

Transform Fault Boundaries

URL: http://pubs.usgs.gov/publications/text/Vigil.html

Source: USGS

Earthquakes and Volcanoes