Upgrade to remove ads
ENSC Final Ch. 14
Terms in this set (21)
When does the Hadean begin?
when the earth/solar system formed, 4.546 billion ± 100 million years ago
When does the Hadean end?
in association with the oldest earth rocks at 4.03 billion years. (basically the first 500 million years of earth history
What is the evidence for the Hadean?
extraterrestrial forms of evidence such as rocks and space debris that date from this time
What other evidence is there for the Hadean?
terrestrial evidence in the form of minerals such as zircons which date to 4.4 billion years
What was the FIRST earth atmosphere likely made of?
composed of H and He which are abundant elements in the universe
What lead to the earths SECOND atmosphere?
H and He being blown away by high speed protons and electrons coming from the sun and replaced by terrestrial gases
What was the SECOND earth atmosphere likely made of?
emerged from volcanic outgassing composed of gasses like H2O, CO2, N2, CH4, CO, HCl, SO2, NH3, and S
How was the atmospheric O2 in the early earth?
very low in concentration until about 2.5 billion years
What minerals have been studied extensively?
about 4.4 billion zircons
What does the data of the traced chemicals of the Hadean tell us?
By 4.4 billion years there was a differentiated crust (leading to plate tectonics) and liquid water (temp. drops)
When were conditions for life on Earth possible?
4.4 billion years
When does the Archean start and end?
It starts at the time of the oldest known rocks (4.03 billion years) and ends when oxygen becomes abundant in the atmosphere (2.5 billion years)
How much oxygen was in the Archean atmosphere?
Not much and very low concentrations
How does the oxygen levels in the Archean atmosphere change?
due to the origin of oxygenic photosynthesis and changes in the Earth process like the burial of organic carbon
What was plate tectonics like o the Archean earth?
"odd" by comparison to plate tectonics because in the Archean, there was a lot more heat and the composition of rocks was different
How were the interactions of plate tectonics on the Archean Earth?
more about softer, flexible rocks and NOT the rigid earthquake/mountain style tectonics
What happened when water mixed in with rocks?
as the composition changed, they became harder and the earth cooled down, plate tectonics began to form like recent ones
What is the Archean?
when we find the first evidence of life on Earth
Based on studying living representatives of ancient organisms, what do living critters tell us about ancestral environments and metabolic capabilities of the earliest forms of life?
the last universal common ancestor of all of life lived in a hot environment and was also anaerobic
Why are these kinds of analyses valuable?
they represent an independent source of evidence that supports the SAME picture that was separately emerging from studying the rocky part of early earth history
How would you describe the early earth?
a hot place without much oxygen and te signature from living organisms supports this
YOU MIGHT ALSO LIKE...
Nats Chapter 6
Astrobiology PHYS13: Chpt 5
EES 112- Ch. 11
OTHER SETS BY THIS CREATOR
341 Mid Term
475 Exam 1
OTHER QUIZLET SETS
Ch. 4 geology
SOC-330 Test 2
Study guide for Unit 5: East Asia
Ast test 1