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Define biosphere
Thin layer of life that exists on surface of planet and interacts with hydrosphere, atmosphere, and lithosphere
Define stratigraphy
Study of rock layers and layering
List Steno's 4 laws of stratigraphy
Superposition, Original horizontality, Lateral continuity, Cross-cutting relationships
Define Principle of superposition
In succession of layered rocks, rock layer at bottom is oldest and layer at top is youngest
Define Principle of original horizontality
Due to gravity, layers of sediment are originally deposited horizontally
Define Principle of lateral continuity
Sediments originally extend out laterally in space in continuous fashion
Define principle of cross-cutting relationships
Rock feature that cuts through another rock feature is younger of the two features
Define principle of faunal succession
Strata of like age can be recognized by the fossils they contain
Why does the principle of faunal succession work?
Species evolve through time
List the subdivisions of time
Eons, eras, periods
Why is the Precambrian less subdivided than Phanerozoic?
There was an extraordinary proliferation of fossils at the base of the Phanerozoic
What do eras represent?
Major change in Earth's biosphere
Base of the Phanerozoic is defined by:
Emergence of creatures with hard parts
Base of the Mesozoic and the Cenozoic based on emergence of:
New species followed by mass extinction
Base of all periods defined on:
Emergence or radiation of new species
3 requirements of mass extinction
At least 30% of Earth's species lost, Across broad range of ecologies, Short/sudden duration (1 million years max)
List Big 5 from most recent to oldest + how long ago
K/Pg 65 Ma, Late Triassic 205 Ma, P/T 251 Ma, Late Devonian 360-375 Ma, Late Ordovician 440-450 Ma
List 3 modes of biologically induced extinction
Competition, Excessive predation, Pathogens
Greater the landmass, (greater/lower) the diversity
lower
List 6 potential causes of P/T extinction
Continental configuration, Sea level fall, oceanic stagnation, climate change, Siberian traps, possible impact
What does continental configuration lead to?
Drop in biodiversity
What does sea level fall lead to?
Less ocean ridge activity
Where was K/Pg extinction event more severe?
Ocean
The extinction of which species is K/Pg famous for?
Dinosaurs
What is the believed caused of K/Pg?
Major extra-terrestrial impact event
List 4 pieces of evidence to support impact theory of K/Pg
Fern spores, tektites, shocked quartz, tsunami deposits
What is the K/Pg impact crater called?
Chicxulub Impact Crater
Location of impact crater:
Yucatan Peninsula of Mexico
List 3 initial (seconds to days) effect of the impact
Vaporization, forest fires from tektites, massive tsunami
List 2 long-term (months to decades) of impact
Global temperature change, acid rain
List 2 other causes of K/Pg event:
Fragmentation of Pangea, global climate change by volcanic activities
The types of creatures most likely to survive changes in environmental conditions from K/Pg even are:
generalists
On land, what type of creatures would survive + adapt to the K/Pg event?
Mammals
What are comets and what are they composed of?
Material left over from formation of Solar System. Icy material and other debris
List the 2 comet "stores" in Solar System
Kuiper belt, Oort cloud
Where are asteroids found?
belt between Mars and Jupiter
What are asteroids?
Material that might have formed another planet.
About how many objects enter our atmosphere every 24 hours?
100 billion
What do craters on the moon tell us about space impacts on Earth?
Earth probably suffered multiple impacts
What hypothesis did D. Raup and J.J. Sepkoski propose in 1984?
Every 25 million years, there's severe stress on biosphere associated with mass extinction event
What' the most important factor in preventing impact on Earth?
Time
What scale assesses threat scale of NEO?
Torino scale
List 3 impact mitigation strategies
Fragmentation, sudden orbit adjustment, steady state orbit adjustment
extraterrestrial impacts have (low/high) frequency but extremely (low/high) cost to society when they occur
low, high
Earth's 2 impact shields are
Jupiter and moon
