impacts

Question 1

people in stratigraphy

Answer 1

steno: suggested deeper layers of rock are older
hutton: uniformitarianism ~ theory that changes in earth’s crust come from universal & uniform processes
cuvier: established different species

Question 2

stages of geological time

Answer 2

precambrian v phanerozoic
paleozoic, mesozoic, cenozoic

Question 3

index fossils

Answer 3

can use to tell what era a rock is from, fossils with a short timeline of existence work best

Question 4

criteria for mass extinction

Answer 4

30% of species extinct
broad range of ecosystems affected

Question 5

5 extinctions

Answer 5

ordovician (450Ma) ~ ice age
devonian (375-360Ma) ~ drastic drop in
oxi levels
permian (252Ma) ~ volcanism, impacts
triassic (200Ma) ~ eruptions, asteroids
cretaceous (65Ma) ~ chicxulub impact, deccan traps

Question 6

generic causes of extinctions

Answer 6

biological changes
impacts
climate change
plate tectonics

Question 7

end-permian extinction

Answer 7

• closest life has come to failing completely
• pangaea caused lack of biodiversity, oceans stagnated, possible impacts, siberian traps led to global warming
• allowed dinosaurs to evolve

Question 8

end-triassic extinction

Answer 8

• caused by volcanism, climate change, possible impacts
• allowed dinosaurs to take over

Question 9

cretaceous/paleogene extinction

Answer 9

• caused by chicxulub impact & deccan traps
• wiped out dinosaurs completely
• impact led to forest fires (warming), then an impact winter (cooling), then release of methane gas (warming)

Question 10

evidence for chicxulub impact

Answer 10

• alvarez hypothesis: iridium anomaly
• fern spores and soot layers evidence of global fires
• tanis fossil site

Question 11

raup & sepkoski’s hypothesis

Answer 11

25 myr cycle in impacts

Question 12

asteroid mitigation strategies

Answer 12

ablation (vaporising)
DART (redirecting)
fragmentation
orbit adjustment
all v expensive and require much notice