Hey, I'll give you what notes I have but I'm not entirely sure if all of them are exactly right. Oh yes, they might be a bit simplistic cos that's how my brain works - in simplistic ways. Sorry if they're not detailed enough.
Oxygen and Ozone
Initially: No oxygen = no ozone
BUT
- 3500 million years ago cyanobacteria began producing oxygen
- Initially oxygen produced precipitated sediments (eg BIF) and this continued til 1700 million years ago
THEN
- 2000 million years ago oxygen began accumulating in the atmosphere
THEREFORE
- So did ozone
SO
- By 1800 million years ago, there were high enough concentrated oxygen levels to produce enough concentrated ozone to protect life on earth
Plates and Plate Boundaries
It's a bit broad... is there any particular part you were after for this?
Plate Tectonic Super Cycle
I have this as a diagram, if you really want it I could scan it in for you.
Volcanoes and Earthquakes
Same as plate boundaries, anything in particular?
Faults
Same with Plate Tectonic Super Cycle
Stromatolites
I had to do this as a speech, unfortunately:
Stromatolites are one of the most ancient life forms that live today. Although they were most abundant in the Precambrian times, modern day stromatolites do exist. Typically they are found in hypersaline lakes and marine lagoons where the harsh conditions make sure that they are left to grow in peace.
Modern day stromatolites have been found in Australia, in the Hamelin Pools of Shark Bay in Western Australia. Here the water is twice as saline as usual sea water and as such animals that feed on bacteria and algae cannot tolerate such conditions. The stromatolites here grow slowly, less than a millimeter a year. But stromatolites have also been found in the Bahamas, thermal springs of Yellowstone National Park in America and even in lakes in Antarctica.
Ancient stromatolites were most abundant during pre-cambrian times. This is probably because there were no grazing animals for stromatolites to fall victim to. During this time, life primarily existed in the sea. The marine environment was much more stable and there was less risk from harsh radiation and, later on, oxygen. Although stromatolites were primitive cells, being prokaryotic, they lived in huge masses that formed widespread reefs.
Like plants, stromatolites use carbon dioxide to produce food and oxygen is given off as a waste gas. The Precambrian eons had an abundance of carbon dioxide and as such stromatolites flourished. But in the process they introduced large amounts of oxygen into the atmosphere. It is then suggested the introduction of oxygen was the next major step in the evolution of life as this gave form to eukaryotic cells. These cells are the basis of all multicellular animals and plants.
In fact, the decline in the abundance of stromatolites coincides approximately with the earliest multicellular animals. While not being direct proof, this does suggest that the evolution of such multicellular organisms (or at least those that ate cyanobacteria and algae) was responsible for the disappearance of stromatolites. This is the general theory for the disappearance of most stromatolites.
However, some scientists dismiss this claim because they say there is no fossil record of an increase in multicellular organisms. Some other theories about the decline of stromatolites include the occurrences of larger sediment accumulation, which would have been less suitable for stromatolites construction.
It is also suggested that there could have been an increase in nutrient levels that killed off the stromatolites, because they prefer habitats with low nutrient levels. However, it is not exactly known just how, or why, stromatolites declined. All we can do is hypothesize. Fossil stromatolites can be found all over Western Australia but the only remaining living ones are found in the costal regions. The likely reason for the decline in stromatolites in Western Australia is linked to the changing climate of the continent.
As water disappeared from the inland areas over the past few million years, the stromatolites were either covered by sediments and fossilized or simply just died off.While stromatolites are seemingly primitive organisms, they played a major role in our history of evolution.
BIF's (Banded Iron Formations)
BIF (layered rocks which are rich in iron and silica)
- Occured during Proterozoic Eon
- Deposited in shallow marine condtions on continental crust (200-300m below sea level)
- Ironstone bands typically 2-20mm
- Banding due to alternate cycling in amount of oxygen and iron dissolved in sea water
PROCESS
Iron in Fe2+ form soluble in water (Fe originated possible from fumaroles)
Oxygen reacts with Fe2+ to provide insoluable Fe3+
Concentration of iron and oxygen varies over time hence the variation in band thickness.
Fossil Formation
Body Fossils
1. Complete preservation
e.g a) mummified humans in peat bog
b) mammoths in ice
2. Partial
e.g bones, teeth, shells, etc
Altered Fossils
a) Permineralisation/petrification
- Bones, trees are porous. Groundwater permiates. Silica carbonate from water causing bone/wood to become solid stone.
b) Recrystallisation
- Unstable minerals replaced by stable ones
c) Dissolution and Replacement
- Groundwater dissolves bone/shell leavin mould. Dissolved silica/carbonate precipate out to give cast
d) Carbonisation
- Preserved as a film of carbon in sandstones/shales
e.g leaves, fish
- Occurs in low to no oxygen conditions.
Evolution
Also a bit broad, but if you want specific sections I'll see if I've got notes on them.
Australian Geographic History
No idea... wasn't even aware we had to do this!
Geologic Time
Just the eons and periods and stuff?
Eon > broken down to an
Era > broken down to a
Period > broken down to an
Epoch
Hadean Eon (4.6 to 3.8 billion years ago)
- Generally thought that life did not exist during this eon
Archean Eon (3.8 to 2.5 billion years agi)
- When life started
- Many rocks were extensively metamorphosed
- Procaryotes (bacteria) became dominant
Proterozoic Eon (2500 to 544 million years ago)
- Eucaryotic single-celled organisms became dominant
Phanerozoic Eon (544 million years to present)
- Development of multicellular organisms.
The Cambrian "Events"
The Cambrian Event refers to the sudden appearance of complex multicellular organisms. This is when animals evolved most of the basic body forms or plans that we can observe in modern groups today. These new life forms had hardened body parts, shells and exoskeletons (e.g Trilobite was covered by an exoskeleton called a carapace) but well preserved fossils from this time have also shown organisms had eyes, intestines, stomachs, digestive glands, sensory organs, epidermis, mouths and nerves.
Some websites:
http://www.theapologiaproject.org/Cambrian.pdf
http://www.geo.ucatgary.ca/~macrae/Burgess_Shale/
http://evolution.berkeley.edu/evosite/evo101/VIIB1cCambrian.shtml
http://en.wikipedia.org/wiki/Cambrian_Explosion
Ediacara
- Not entirely sure but I thought they were soft-bodied organisms that came before the Cambrian Event's hardened body parts, etc.
Well, I hope that helps. If you don't understand it, or want more, etc, just say. I'd like to help cos E+E people don't get too much compared to the other sciences.
