Dynamic planet

‘SIDE VIEW’

100,000 ly

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


Nebular hypothesis
Important theorists: Emanuel Swedenborg (1734), Immanuel Kant (1755), Pierre-Simon
Laplace (1796), Victor Safronov (1972) – Solar nebular disk model (SNDM)

Evidence: observations systems at varying stages

1. Nebula: Giant Molecular Cloud (GMC) results
from collision(s) or explosion of dying star
3. H and He condense into Sun
4. Disk of matter (many elements) around sun
5. Disk slowly accretes into clumps (planetesimals)
that also contain heavier elements
6. planetesimals → planetoids →
planets and satellites
Hubble Space Telescope
view of a new solar system
1500 l-y away in the Orion
Nebula

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)


Red ovals
indicate
major
extinction
events:
when
extinction
rate greatly
exceeds
speciation
rate



The Earth in

cross-section


Upper mantle
and lithosphere


ISOSTASY

Elevation of tectonic plates
determined by density/thickness

Mountain masses
displace mantle
material

Isostatic adjustment
due to loss of mass
by erosion

Deformation from
sediment load



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/lava)
• Sedimentary
(settling & cementation)
• Metamorphic
(altered under pressure)



• from magma
(molten rock
beneath the
surface)
• intrusive or
extrusive
(from lava)


Laccolith
Sill
Dike

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
Sandstone
Siltstone
Shale
Limestone
Coal

largest clasts
sand cemented together
derived from silt
mud/clay compacted into
rock

calcium carbonate, bones

and shells cemented or
precipitated in ocean waters
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