‘SIDE VIEW’ ‘TOP VIEW’ Solar System on outside of 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? exploded 2.Nebula (cloud of dust and gas) results 3.H and He condense into Sun 4.Disk of matter (many elements) around sun 5.Disk slowly accretes into clumps (planetesimals) 6.planetesimals  planetoids  planets (including Earth) and satellites

Eons, Eras, Periods and Epochs Superposition: youngest rocks superimposed on older rocks “Relative time” Dating by radioactive isotopes Half-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 ovals indicate major extinction events

The Earth in cross-section

Upper mantle and lithosphere

Mountain masses displace mantle material Isostatic adjustment due to loss of mass by erosion Deformation from sediment load ISOSTASY Elevation of tectonic plates determined by density/thickness

Mineral A natural, inorganic compound with a specific chemical formula and a crystalline structure Examples silicates (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

Conglomeratelargest clasts Sandstone sand cemented together Siltstonederived from silt Shale mud/clay compacted into rock Limestone calcium carbonate, bones and shells cemented or precipitated in ocean waters Coal 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 GraniteGneiss Basalt Schist Limestone, dolomiteMarble SandstoneQuartzite

Crustal Movements

Continents are adrift due to convection currents in the asthenosphere Mantle movements result in plate migration 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: (animation)

Divergent Boundaries (constructional) Convergent Boundaries (destructional) Transform Fault Boundaries

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Source: USGS

Earthquakes and Volcanoes