GEOS1211 Lecture Notes - Lecture 3: Continental Crust, Oceanic Crust, Pedogenesis
14 Jun 2018
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Lecture 3 and 4 learning outcomes
• Appreciate how the Earth formed and its uniqueness
Earth formation->
- ~ 5.5 billion years ago the proto-Earth and other planets condense from gases, dust and
plnetismals
- Heating due to friction and compression resulted in a proto-Earth that was largely molten
with an outer crust
- Inner planets- terrestrial, outer planets- gas giants
- After initial accretion of coolish planetismals, proto-Earth rapidly heated up, formed its
metallic core within 100 million years
- Molten exterior which quickly cooled to a crust
- After ~4 billion years, the crust begins differentiation into lighter silicic and denser basaltic
-
Eath’s uiueess->
- More than half of Earth is covered by water
- Atmosphere is oxygen rich with water vapour clouds
- Diversity of plants and animals
- Goldiloks state- the Earth is at a distance form the Sun such that it receives just enough
heat to keep water from freezing and not so much that it boils
- Enough energy from radioactive decay in the core to fuel the convection cells that keep the
plat tectonics conveyors moving- without these there would be no weathering, erosion of
nutrient for soil formation
- Moon causes ocean tides that create intertidal zones from which the first plants and
amphibians were able to colonise continental environments
- Eath is ostl a losed sste ad he thigs happe soehee o the Eath’s sufae
the effects can ripple through the whole system
• Compare and contrast physical properties of different planets
Mercury
- Large iron core and a weak magnetic field
- Surface is densely peppered with impact craters and a large multi-ringed basin
- The surface facing the Sun can reach 425 degrees Celsius and the dark side can reach -170
degrees Celsius
- Mercury, Venus and all natural moons are spin orbit coupled
Venus
- Resembles Earth in size and density but lacks a magnetic field
- Slow, retrograde, rotation probably due to drag from the westward-rotating atmosphere
hih is 90 dese tha Eath’s ad osists of ao dioide, ~3.5% itoge ad taes of
water and sulfuric acid
- Strong greenhouse gas effecr gives the surface a nearly uniform temperature of 460 degrees
Celsius
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture 3 and 4 learning outcomes: appreciate how the earth formed and its uniqueness. ~ 5. 5 billion years ago the proto-earth and other planets condense from gases, dust and plnetismals. Heating due to friction and compression resulted in a proto-earth that was largely molten with an outer crust. After initial accretion of coolish planetismals, proto-earth rapidly heated up, formed its metallic core within 100 million years. Molten exterior which quickly cooled to a crust. After ~4 billion years, the crust begins differentiation into lighter silicic and denser basaltic. More than half of earth is covered by water. Atmosphere is oxygen rich with water vapour clouds. Diversity of plants and animals (cid:862)goldilo(cid:272)ks state(cid:863)- the earth is at a distance form the sun such that it receives just enough heat to keep water from freezing and not so much that it boils.
