1 Origins Of Earth Flashcards
What are the key theoretical ideas supporting the Big Bang
Einsteins theory of relativity
Cosmological principle
What are the important observations that support the bbt
1 universe is expanding, we know this because the wavelength of light from objects moving away from the observer are shifted towards the red end of the spectrum (red-shift)
2 composition of the universe, the fact 25% is helium and 75% is hydrogen matches predictions.
3 Cosmic microwave radiation, we are looking into the past and the fact CMR can be found everywhere proves it was hot in the beginning.
When and How was earth formed
Formed an estimated 4540 million yrs ago from colliding planetesimals and other celestial objects which agglomerated into a planet
Earths layers
Oceanic crust
Continental Crust
Lithosphere
Athenosphere
Upper mantle
Lower mantle
Outer core
Inner core
What are BIFS
Most of the iron and silicon probably came from upwelling iron-rich, deep ocean currents derived from ocean floor volcanic systems. Runoff from the continents brought minerals into the oceans as well. When aquatic photosynthetic organisms (Cyanobacteria) evolved they produced lots of oxygen as waste. The waters at the time had iron particles, which reacted with the oxygen to form iron oxide which settled on the ocean floor. These particles accumulated and eventually created layers of iron rich strata known as BIFs. Can be found in the Hamersley Province in the Pilbara region of Western Australia and I estimated to be around 2470 to 2450 million years old.
how do bifs form
BIFs form when iron-rich chemicals precipitate out of the oceans during iron-rich phases of ocean history.
index fossils
-by using relative dating you can determine the age of rock strata by the inclusion of fossils (e.g trilobites, ammonites and gastropods)
-fossils will be older than enclosing strata and (principle of inclusions)
-the fossil is useful for determining the age of the rock strata
Explain the origin of banded iron formation
The early oceans were very oxygen rich. When the early cyanobacteria produced oxygen through photosynthesis it combined with iron to form iron oxide (rust)
