eosc 114 - impacts ❗️❗️❗️❗️ + fragile systems 2

1 ma

1 mega annum : 1 million years 1 000 000

10^6 years

understanding of earth’s geological history is built:

• understanding that earth is a system

• steno’s laws of stratigraphy (layering of earth)

• bio stratigraphy (fossils)

• correlation

• radiometric dating

five major extinction events NEWEST TO OLDEST

extinction occurs in PERIODS that are WITHIN ERAS, multiple epochs can occur in a period

1. (newest) end of cretaceous period (66ma)

2. end of triassic period (200 ma)

3. end permian period (250 ma)

// end of Paleozoic era, entering Mesozoic era

4. end late devonian period(360 ma)

5. (oldest) end late ordovician period (450 ma)

CTP DO

what defines a mass extinction

• 30% species are extinct

• broad range of ecosystems affected

• extinction happens QUICKLY in relation to the geological timescale

taxonomy

• species are a must be capable of interbreeding

  • extinct species - we use their physical characteristics to identify them

KPCOFGS

kingdom

phylum

class

order

family

genus

species

most recent mass extinction : CRETACIOUS

cretaceous period: 66ma

• asteroid impact

  • 75% species extinction globally

triassic mass extinction

• 200 ma

• MAYBE massive volcanic eruptions, asteroids

  • 70-80% of species extinct globally

permian mass extinction

• 250 ma

• asteroid impacts

• intense volcanic activity

  • 95% of species extinct globally

THE GREAT DYING ❗

devonian mass extinction

• 375-360 ma

• drastic drop in oxygen levels

  • 75% of species extinct globally

ordovician mass extinction

• 445 ma

• PROBABLE CAUSE: intense ice age

• 60%-70% of species extinct globally

causes of mass extinctions

• biological causes

• plate tectonics

• climate change

• extraterrestrial events

biological causes of extinction

• generally leads to extinctions but not mass extinctions

COMPETITION, PREDATION, PATHOGENS

• effects on earth system : ex first soils washed into oceans caused anoxia

plate tectonics as a cause of extinction

can lead to changes in climate and sea level

• ex. late Ordovician glaciation was likely promoted by movement of gondwana to south pole

• supercontinents: pangea, gondwana, nuna

  • DECREASE OF BIODIVERSITY

climate change as a cause of extinction

in geological past, sudden climate changes were typically caused by volcanism + FLOOD BASALTS

• long term shifts of icehouse/greenhouse were influenced by volcanism

icehouse→ ice at poles

greenhouse → no ice at poles

extraterrestrial events as a cause of extinction

• asteroid impacts (cretaceous mass extinction)

• gamma radiation bursts ( possibly end of ordovician mass extinction)

  • galactic cycles

overall causes of mass extinctions

tends to be caused by a combination of factors

• causes that disrupt the earth’s system, therefore the BIOSPHERE

• it is never really one specific cause

end permian mass extinction

251 ma - THE GREAT DYING; 90-96% species extinct

permian world

• supercontinent pangea

  • huge and dry → collapse of carboniferous rainforest 300ma

  • by 290ma, forests were vast deserts and an ice cap in the southern hemisphere → ARID WASTELANDS

fewer ecological niches on the land + fewer continental shelves in the oceans

• OCEAN STAGNATION

  • polar waters couldn’t sink, bad ocean circulation, anoxia

• SEA LEVEL FALL

  • mid-ocean ridge activity (spreading center) slowing in the Permian

AT THIS TIME, an impact breccia (shockwave + massive shattering/melting and solidification) might’ve occurred

• SIBERIAN TRAP - 3million km³ of basalt lava eruption that released lots of CO2 and methane + ERUPTION SET FIRE TO LARGEST COAL+OIL deposit on earth at the time

  • massive amounts of greenhouse gas, soars in global temperature, climate change (MAJOR INCREASE OF GHG)

• METHANE CLATHRATE MELTING - added to climate change, bottom of ocean decay of organic material it is a deep sea sediment

  • warm ocean → melting of clathrates → methane release METHANE IS STRONGER OF A GHG THAN CO2

in the ocean: 40C on average, reef collapse, anoxia

on the land: 50-60C on average, no trees, acidic rain to live you’d need to be able to burrow, eat little, and not breathe

what effected the permian extinction

• pangea is dry

  • already ocean stagnation and sea level fall

• IMPACT BRECCIA

• SIBERIAN TRAP

• METHANE CLATHRATE MELTING

triassic

251ma (permian) it took until 230 ma ( 20ma) for earth to recover pre extinction levels of coal

• due to the ecological room for evolution, DINOSAURS CAME TO BE after the end triassic mass extinction

• dinosaurs lived until the next mass extinction — triassic (200ma)

triassic coal gap

there was no coal on earth after permian period for 20 million years

what did the permian period extinction leave behind

• absence of coal for 20 million years

• lots of ecological space — opportunity for survivors to evolve and dominate available ecological niches

end triassic mass extinction

70-80% of species extinct

• more than half of animals and around 60% of plants

• decline in ammonites

• extinction of conodocts

STILL UNCLEAR WHAT CAUSED IT - lots of impacts but they were either too small or too young/old

• attributed to CAMP - central atlantic magmatic province

  • volcanism and climate change played a role

CAMP - central atlantic magmatic province

during the triassic period

3 million km³ of basalt erupted at 201 ma → LARGE AMOUNTS OF CO2 + sulphur dioxide

• oceans were acidifed, carbon deposition stopped (no more absorption of co2)

• atmospheric co2 doubled, sulphur dioxide cools but NOT ENOUGH

• climate change

what did john spray notice about impacts

there is a change in the geological time scale and impacts DO NOT overlap in time.

• triassic jurassic boundary

triassic jurassic boundary

• visual evidence of the growth of dinosaurs in evolution in the triassic period (when they existed but weren’t dominant) and in the jurassic period (when they were dominant)

  • dinosaurs adapted to their ecological niches by ADAPTIVE RADIATION

what mass extinctions led to the rise of dinosaurs

end triassic and end permian

uniformitarianism

“the present is the key to the past”

• used by earliest geologists to measure modern geological processes and estimate how long it would take to build the crust

  • the natural laws and processes that operate in the past world today have always operated in the past and apply everywhere

physics

lord kevin : rate at which a molten body of rock the size of earth would cool

• 20-40 million years

radiometric dating of how old earth is

4.6 billion years

• based off radioactive decay of isotopes of meteorite material

• oldest rock 4.03 billion years

  • oldest meteor 4.54

geological timescale

earth’s 4.5 billion year old history is organized into this

• eons, eras, period, epoch

clowns only shoot ducks carrying people that just cant play quietly

(oldest → newest)

cambrian

ordovician

silurian

devonian

carboniferous

permian

triassic

jurassic

cretaceous

paleogene

quaternary

precambian eon

over 4 billion years in which earth had no plants or animals

makes up 87% of earth’s history

earth system science

study of earth as a system with interconnected parts

• lithosphere, hydrosphere, atmosphere, biosphere

  • biosphere is likely easiest thanks to fossils

ecosystem

community of organisms and their environment

• primary producers

• marine terrestrial flying animals

• water, ice, air

HAVE CHANGED OVER TIME

ordovician oceans

~450 ma

• nautiloids declined after ordovician period

• graptolites, brachiopods (major decline), trilobites (extinction) affected by end permian

• end triassic: conodocts mass extinction

cretaceous oceans

~130 ma

• turtles

• marine reptiles, plesiosaurs

• mosasaurs

• diving birds

• ammonites + ray finned fish

bolded: extinct in end cretaceous

stratigraphy and its varieties

• chronostratigraphy

  • in time

• lithostratigraphy

  • rock type

• biostratigraphy

  • fossils

• chemostratigraphy

  • chemistry

history of stratigraphy

1669 - steno suggested that deeper layers of rock must be older

1760s - ardunio started naming layers of rock in the alps based on depth and composition

1780s - button “uniformitarianism”

deeper : first

then layer establishment

uniformitarianism

stratigraphy

BUILT ON THE ORGANISATION OF LAYERS OF ROCK (STRATA)

f 2 rocks contain similar fossil species, they are likely to have been deposited from the same/similar time

• can define biozones, which correlate rocks of similar age

ONLY WORKS BECAUSE SPECIES HAVE EVOLVED

• huge amount of geological time was organised using fossils and still is today

extinction

was understood before evolution

• there was a conclusion that elephants and mammoths are distinct species

• there was also a conclusion that mammoths were once a living species but became extinct

  • tells us that fossils were once living before they became extinct

how was the chronostratigraphic chart accomplished

identifying rocks which are on top of others (biostratigraphy) and radiometric dating

law of superposition STENO

guiding principle of stratigraphy which states that rocks on top are younger than the rocks beneath

principle of original horizontality STENO

even if strata and rocks are tilted or folded today, they were originally flat

principle of lateral continuity STENO

OFTEN (but not always) layers of rock can be traced out laterally

• they are continuous until they encounter other solid bodies that block their deposition ex. water

principle of cross cutting relationships STENO

IF ONE ROCK CUTS THROUGH ANOTHER, it must be younger

(crack in old rock is filled with new rock, new rock is younger")

unconformities

period of non deposition / erosion that disrupts stratigraphy

faulting

layers of rock can be offset by faults → disrupting stratigraphic sequence

push up “ reverse fault”, hanging down “normal fault”

faunal succession

fossils must change over time for biostratigraphy, reason for this: evolution

• there are species that are ideal for biostratigraphy : INDEX FOSSILS

index fossils

1. common

2. white geographical distribution

3. short range: greater resolution of age (distinctive start and end) + SHORTER TIME A SPECIES EXISTED FOR

4. died in an environment with good fossilization and preservation

AMMONITES extinct from cretaceous end

adaptive radiation

Rapid diversification after a mass extinction into new forms and species

• open new ecological niches, new resources and new selection pressures

background extinction

not all extinctions are mass extinctions

• background extinctions wipe out 5-10% of the species per million years while mass extinctions wipe out 30% or more in one go

• dodo birds

sixth major extinction?

the appearance and migration of modern humans may be associated with greater numbers of extinctions

• for mammals, the current extinction rate is about 30 000 times faster than the background rate

the cretaceous palaeogene extinction ( K/PG EXTINCTION EVENT)

dinosaurs first appeared 240ma (in the triassic period) on pangaea; went extinct at the end of the Cretaceous period at 66 ma

• at least 50% of all species went extinct including dinosaurs

  • on land no animals larger than a dog survived minus alligators and crocodiles

  • 80-90% of marine species went extinct

  • half of plants went extinct

  • all non avian dinosaurs went extinct. birds survived and are now considered part of the dinosauria clade

what is a hypothesis that explains the cretaceous palaeogene extinction

ALVAREZ HYPOTHESIS

• the impact of a large asteroid

• led to the discovery of the iridium anomaly

• 1cm clay layer at the top of the cretaceous layer that is RICH IN IRIDIUM

• iridium is rare on earth’s surface

• MORE COMMON IN ASTEROIDS !!!!!!

suggested impact of a 10km + asteroid

ALVAREZ hypothesis / k-pg impact

iridium anomaly layer at the top of the cretaceous

• found all over the world

• NASA deep impact : confirms high amounts of iridium in comets and asteroids

soot concentration in iridium anomaly: FORM OF BLACK CARBON produced by burning organic matter

• suggests that there were massive forest fires on a global scale

fern spores: first plants to colonize burned landscapes : excess of ferns = FERN SPIKE

tektites: natural glass particles produced by melting rocks during an impact

shocked quartz : lots of internal fracturing, which form when extraterrestrial impacts produce intense seismic waves that shatter rock : Magnitude 16 earthquake (omg)

• shock lamellae : cross hatched lines in grain of quartz

chicxulub impact crater: crater that was formed in Mexico 66 ma ago by a 10 km wide asteroid

tanis fossil site 2022: broken remains of dinosaurs, broken fish fossils with tektites in gills (implying that tektites would have rained down across north America as they tried to breathe)

what made it worse:

• limestone platform

• dust

• evaporites → sulphuric acid rain

• deccan traps

chicxulub impact crater

mexico 66ma perfectly in time to serve as strong evidence of being the asteroid event on the boundary of the cretaceous period

• 10 km wide

• layers of shocked quartz and tektites

• concentric ringed structure

• central peak

ROCK CALLED SUEVITE IN THE CRATER, suevite is a breccia (fractured) rock formed during impacts

• contained evaporites : high rates of evaporation → precipitation of salts. evaporite minerals are rich in sulphates leading to sulphuric acid rain

  • devastated primary producers like phytoplankton

after the kpg impact

• tonnes of dust would have COOLED THE PLANET and caused impact winter for years (freezing temperatures)

• dust blocked sunlight and no more photosynthesis would occur

• biological production and food chains collapsed in lands and oceans

the asteroid hit a carbonate platform full of limestones which increased atmospheric co2; vaporization during the impact : global temperatures rose 2-8 degrees which lasted for decades

deccan trap

erupted in indea in 66 ma as well : large igneous province with lots of flood basalt lava

• this eruption may have contributed to the cretaceous palaeogene KPG mass extinction through the release of co2 and so2

• iridium layers in basalts told us the year in which this happened

AFTER THE IMPACT, GLOBAL VOLCANIC ACTIVITY DOUBLED, which added to the stress on the biosphere

KPG extinction conditions

• cretaceous biosphere was already stressed

• deccan traps influence climate

• breakup of pangea also meant changes in environments

asteroid was the main cause of extinction for dinosaurs

• MAMMALS WERE BEST ABLE TO BURROW, HIDE, AND HIBERNATE, hence they were able to survive the conditions best

what animal today is the only surviving group of dinosaurs

modern birds

meteoroids

• rocks smaller than 1m

meteors: as they enter earth’s atmosphere

meterorite: if it survives entry to earth’s atmosphere as an in tact rock

bolides: fireballs that explode in the atmosphere

SOURCE: ASTEROID BELT BETWEEN MARS AND JUPITER

asteroids

• larger rocks (1m >); smaller than a planet

• rocky and metallic

• can be dwarf planets

SOURCE: ASTEROID BELT BETWEEN MARS AND JUPITER

comets

rock mixed with ice that are leftovers from planet formation

near the sun it has a tail of gas and dust particles

SOURCE:

1. kuiper belt

2. oort cloud

asteroid belt

meteoroids and asteroids come from the asteroid belt located in orbit of mars and jupiter

kuiper belt

similar to asteroid belt but larger

• composed of frozen volatiles like water, methane, ammonia (ices)

• more dwarf planets like pluto are here

  • some of the solar systems moons are believed to have originated here (neptune and saturns moons)

oort cloud

1000x farther from sun, halfway to alpha centauri

• “edge of solar system”

• composed of mostly ices

• source of halley’s comet and hale boop

meteor influx

100 billion meteroids hit earth’s atmosphere every day

• log graph

• it is expected that a 10km sized object hits earth every 100 million years on average

shoemakers hypothesis

geological changes can arise from asteroid strikes, asteroid strikes are common, and impact craters form large circular structures associated with impact ejecta, shocked quartz, etc

• shoemakers studied ries crater and noticed the building stone was suevite → 14 ma impact crater

  • we found more than 200 other examples on earth now, one of the oldest being in quebec : 214 ma

raup and sepkoski’s hypothesis

• “there is believed to be a 25 myr cycle in impacts and extinctions”

• possibly due to the gravitational distribution of the oort cloud. possibilities?

  1. nemesis, the companion star

  2. planet 9

  3. movement through galactic plane

  4. could just be a coincidence

theory of oort cloud that could be responsible for the 25 myr extinction: NEMISIS

• the sun has a companian star far beyond the oort cloud whose orbit comes every 25 myr

• gravitational effects kick comets more into inner solar system

• if it were a brown dwarf or a black hole, it would be hard to detect

  • no evidence so far

theory of oort cloud that could be responsible for the 25 myr extinction: planet 9

• existence of a distant planet far beyong neptune could shift oort cloud orbit

• possibily came from viewing orbits of distant solar system bodies

  • no evidence so far and it is believed that it is unlikely

theory of oort cloud that could be responsible for the 25 myr extinction: moving through the galactic plane

• solar system orbits through center of galaxy

• galaxy isnt flat but has thickness of stars and material

• as we move (sin graph shape kinda) through the denser parts of the galaxy, oort cloud could be disturbed

theory of oort cloud that could be responsible for the 25 myr extinction: chance, it isn’t actually a thing

• there could be no cycle

• dating and spacing is not always consistent

• there have surely been more impacts that we arent sure of (deep sea ocean, etc)

• we know that meteorites hitting isn’t the only cause of extinction

as such: NASA things the raup sepkoski hypothesis is not needed

our concern?

• possibility of global catastrophe is a concern

• civilisation ending impacts occur randomly and every 1 million years

tunguska russia, chelyabinks russia, near misses

tunguska russia

air blast; no impact crater levelled 3100 km² of forest and sent a shockwave around earth 2 times

• no clue what it was as it was not on the ground, could have been or comit or an asteroid that bounced back and could still be orbiting the sun

• it happened in a foresty area, if that happened in mainland, it would flatten from west vancouver to langley

chelybinsk russia

20 m asteroid that exploded 30km off ground (bolide)

• entered atmosphere without warning and approached from the direction of the sun

asteroid 2019ok

july of 2019

100m diameter asteroid that passed within 73000 km of earth (1/5 distance to the moon), confirmation of existence was just 3 hours before it passed

asteroid 2005yu55

november 2011

360m diameter asteroid that is 4/5 of moon’s orbit; discovered 6 years before it passed earth

will come back in 2041

2075

eastern mediterranean event

june 2002

meteor air burst above mediterranean sea

unknown object and no fragment

similar to a small nuclear bomb

asteroid 99942 apophis

will approach earth 2029

370m diameter will pass 10x closer than the moon and closer than all communication satellites

• believed to not hit earth, if it does, 5 km crater but no impact winter

comet shoemaker levy 9

jupiters gravity broke the comet apart, if it had hit earth, it would have wiped out life on the microbial level

jupiter: cosmic vacuum cleaner

our moon is large and it shields earth from potential impacts

torino scale

communicates threats of impacts on a scale from 0-10

• risk assessment

spaceguard survey

identifies, catalogues, and studies near earth objects

• asteroids larger than 1km are surveyed

  • large objects (esp those that can cause mass extinction) are tracked

neo surveyor spacecraft

planned space based infrared telescope that will survey the solar system for hazardous asteroids

dart (double asteroid redirection test)

testing to see if we can alter an asteroids impact by using an impactor

how are impact hazards unique

• can be most devastating

• are the only natural disaster that can be completely avoided

• most important factor: TIME

mitigation strategies for impacts

1. fragmentation

2. rapid orbit adjustment

3. gradual orbit adjustment

4. ablation

5. ride the solar winds

fragmentation as a mitigation strategy

• blowing asteroid up

• we need to land on the asteroid and drilling into it

• creates risk of multiple impacts + long preparation time

rapid orbit adjustment as a mitigation strategy

• nuclear warhead or smash a projectile into the asteroid

  • requires warning period

gradual orbit adjustment as a mitigation strategy

• using chemical, electric or nuclear propulsion

• keeping an orbit the way we want it

  • predictable as we already use it for satellites but it requires a warning period

ablation as a mitigation strategy

• focusing sunlight onto the surface of asteroids or using lasers to flash vaporize or ablate the asteroids mass/ deflect the objects path

• we would have to place a satellite in orbit around an asteroid

riding the solar winds as a mitigation strategy

• installation of solar sails / mirrors on the asteroid ; radiative pressures from sunlight would deflect it

• requires a very long warning time

mitigation strategies

are real and there are many implementations being tested + it is being taken very seriously

however: all methods require research, warning time, and money

impacts are also very low frequency, we have cancer, climate change, hiv, pandemics, should we divert the money to impacts?

micromort

unit of risk:

1 in 1 million chance of death

micromorts a day = 23

value placed on risk: 1 micromort 50$

what goes in a preparedness kit

food for at least 3 days and water for a week

flashlight + batteries

radio / handcranked battery

meds blankey

charger pen notebook

poopoo stuff

teeth brushies

first aid

glasses and contacts

small bill cash

whistle

map

pico is?

nano is?

micro is ?