EX Learning Goals

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