Deep Time Earth Quiz - lectures 1-6 Flashcards
What are the abbreviations for billions and millions of years ago?
Billions - Ga
Millions - Ma
The first 3 eras of the Precambrian and the major eon that follows i.e. the 4 major eons into which geologists divide Earth’s history into?
Hadean 4.6-3.8 Ga
Archean 3.8-2.5 Ga
Proterozoic 2.5-0.54 Ga
Phanerozoic 0.54-0 Ga
How old is the universe? How old is the Earth?
- 7 Ga
4. 6 Ga (4.56)
Which two elements were made as the universe cooled after the big bang? What process has made the other elements? What is the heaviest?
Hydrogen (H) and Helium (He)
The process of nuclear fusion in stars; stops at iron (Fe) as this is the heaviest and stars run out of fuel eventually
How are even heavier elements than Fe made?
Larger stars explode into supernovas and through neutron capture, become neutron stars
What is the process of rocky planet formation called? What heated the earliest Earth?
Accretion
Kinetic energy from accretion converted to hear followed by radioactive decay
What elements form most of the Earth’s core and mantle? How were they differentiated?
Core = Fe
Mantle = Si
Iron and Silicon are immiscible; Fe is denser so remained in core
How was the moon formed?
Collision with ‘Theia’; a planetary embryo about size of Mars
Where did the oceans and atmosphere come from? Name two abundant gases in early atmosphere
Volatiles vapourized by immense heat and LHB etc. Degassing from the mantle resulted in atmosphere and some water from carbonaceous chondrite meteorites
N2 and CO2
How old is the oldest zircon grain, and how old are the oldest rocks still with us at the Earth’s surface?
Zircon grain = 4.4 Ga
Oldest rocks = 4.28 or 4.04 Ga (differences in accepted evidence)
When was the ‘Late Heavy Bombardment’ and when did life originate?
LHB = 4.1-3.8 Ga Life = 3.8 Ga is earliest proposed evidence
How old are the oldest sedimentary rocks and how old are the oldest fossils of life? What is a stromatolite?
Sedimentary rock = 3.8 Ga
Fossils = 3.5 or 3.26 Ga depending on evidence accepted
Stromatolite = fossilised layered carbonate rock structure, made by microbial communities
Who came up with the theory of continental drift?
Alfred Wegener
Evidence for sea floor spreading (x2) and subduction of ocean plates?
Paleaomagnetism: symmetric magnetic reversals either side of mid-ocean ridge AND thickening sediment layers with distance from ridge
Seismic activity provides evidence of plate boundaries
Hold old is oldest ocean floor and roughly how fast do continental plates move apart/together?
150 Ma
10cm/yr (100mm/yr)
What is the process of splitting called and what is created upon collisions?
Rifting
Mountain ranges
Name of ancient bits of continental crust, a surface location above a mantle plume, and landform above continental crust plume?
- Cratons/shields
- Hawaii (Mauno Loa)
- Flood basalts, or Large Igneous Province
Co-existing dis-equlibrium gases? What dominates Mars and Venus’ atmospheres?
Oxygen and Methane OR oxygen and hydrogen
CO2
Gaia hypothesis: what is regulated by life? Who created it?
Atmospheric composition and climate
By Jim Lovelock and Lynn Margulis
What are some key criticisms of the Gaia Hypothesis and how did Lovelock respond?
Biologists - implies teleology and forethought, not a unit of selection, not natural selection for a wider purpose
‘Daisyworld’ model = biological alterations to environment and climate automatically
What is the habitable zone?
Range of distances from a star on which water on a planet is liquid (0-70 degrees temp range)
What is the faint young sun puzzle? Role of luminosity, temperature, cycles etc.
Sun was 30% less luminous when Earth formed.
High CO2 levels and perhaps lower albedo kept Earth warm
Silicate weathering was the long-term process that removed CO2 from the atmosphere which counteract steady brightening of the Sun (warming accelerates silicate weathering and removes CO2)
