snowball earth!

Question 1

how did we get the snowball earth?

Answer 1

supercontinent at equator, equator parts (hot and wet), chemical weathering, suck CO2 out of atmosphere, bring it into oceans

Question 2

how many glaciations happened?

Answer 2

3

Question 3

HOW TO GET INTO / OUT OF GLACIATION

Answer 3

as planet begins to cool
1. tipping point where glaciers are moving toward the equator
2. pass 33 degrees
3. runaway albedo (reflectance) snow reflects the light
4. incoming radiation bounces back to space
5. doesn’t heat up planet
6. creates global glaciation

can’t stay here forever because…

1. plate tectonics + there are always volcanoes that are going to provide heat and produce CO2
2. left with a bunch of fine grained powder due to super fast chemical weathering
3. creates hot house (goes from cold to super greenhouse/super hot very fast)

Question 4

physical evidence for glaciation!!!

Answer 4

• conglomerates with particles carried by glaciers in places it shouldn’t be
• must have had ice
• weathering a lot of stuff = super fast limestone formation
• stromatolite tall and thing = growing super fast = fast sedimentation, lots of bicarbonate available due to weathering on land
• band iron formation: only can build up if there is no oxygen, no oxygen at that time because oceans are covered with ice, iron build up under ice, ice melts, iron wash out,

Question 5

animals come after first glaciation, what do they come from?

Answer 5

• come from bacteria and algae

Question 6

why did animals arise?

Answer 6

ediacaran fauna (soft bodied marine animals preserved in impressions)

Question 7

we know that life must have existed, but where / how isn’t fully known. regardless, what are our assumptions for animal life evidence?

Answer 7

dirty snow, pockets of water, puddles on top of glacier due to dirty snow

Question 8

why was animal rise significant?

Answer 8

macroscopic: we can see it

Question 9

what two locations did we see animal rise?

Answer 9

austrialia and newfoundland

Question 10

often find a whole community of organisms, not just individual. what is the term for this?

Answer 10

lagerstatten

Question 11

bioturbation

Answer 11

trace fossil - tracks something that lived (fossilized footprint of dionsaur)
things like worms creating a trail
able to say that this looks like an old worm burrow or something

Question 12

biomineralization

Answer 12

organisms form a shell to protect themselves from predators

Question 13

predation

Answer 13

organism to organism interaction