Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
30 Cards in this Set
- Front
- Back
|
Hadean |
- 4.5 - 3.8 Bya - Hades - no rocks this old (some isolated zircon crystals) - formation of solar system |
|
|
accretion disk |
large cloud of gas and dust |
|
|
how did the sun form |
within an accretion disk, shrinking in on itself by self gravitational collapse until it went nuclear fusion to give off light and heat |
|
|
how were planetismals created |
surrounding particles began to coalesce due to gravity into larger lumps |
|
|
newtons law of universal gravitation (gravitational attraction) |
Fa= G (m1 x m2) / d(^2) |
|
|
hwo is sun differentiated |
material density |
|
|
when did earth's surface solidify |
first 100 million years of the solar system |
|
|
3 possible scenarios for the formation of the moon |
- asteroid captured by Earth's gravitational field - body that accreted from material trapped in Earth's orbit - portion of the earth knocked loose by a large bolide impact |
|
|
moon |
- planetismal mass roughly size of mars - enriched in Fe and Mg relative to Earth's mantle - composed largely of material from impactor - accreted from disk of material around Earth following impact |
|
|
origins of oceans |
- formed mostly from water vapor emitted during volcanism - some input from comets - salts derived from weathering - liquid ocean present prior to end of Hadean |
|
|
stability of ocean salinity |
since the Archean |
|
|
pillow basalts |
- isu formation, greenland are 3.8 Ga |
|
|
early earth's atmosphere |
- composed primarily of volcanic gases (CO2, N2, H2, NH3, CH4, HCl) |
|
|
how was oxygen for early atmosphere produced |
in very small quantities from the breakdown of water vapor by UV light |
|
|
how is vast majority of today's oxygen created |
photosynthesis |
|
|
Archean |
- 3.8 - 2.5 bya |
|
|
primary producers of oxygen in precambrian |
- photosynthetic bacteria in stromatolites |
|
|
great oxygenation event |
photosynthetic organisms produce huge amounts of oxygen |
|
|
banded iron formations |
- sedimentary layers confined to 1.8 - 3.5 Ga - composed primarily of iron oxide minerals - rusting of ocean - first deposits may coincide with origination of photosynthesis |
|
|
precambrian atmosphere |
- anoxic until 2.5 - 2.0 Ga - levels of oxygen then increased dramatically to about 15% |
|
|
proterozoic eon |
- modern tectonics - first evidence of )2 build up - first abundant fossils - oldest major glaciation |
|
|
eukaryotic cells |
- first appear around 1.8 Ga - single and multicellular organisms that have nucleus |
|
|
prokaryotes |
single celled organisms that lack a nucleus |
|
|
when do trace fossils by burrowing animals appear |
end of proterozoic |
|
|
snowball earth |
- worldwide distribution of neoproterozoic glacial tillites - entire earth covered in ice - 2-3 ice ages - could explain delay in appearance of multicellular animals |
|
|
albedo |
reflection coefficient |
|
|
albedo of snow and ice |
45 to 95 % |
|
|
albedo of seawater |
10 % |
|
|
albedo of forests, grasslands soil |
5 - 30% |
|
|
what geologic process can reverse a snowball earth or ice albedo |
plate tectonics! |
