Exam Revision Flashcards
What is Fermi’s paradox?
The high probability that extra terrestrial life exists and the lack of contact humans have had with such life.
Why haven’t other planets with much older solar systems in ours developed life, and life that is intelligent enough to travel throughout space
Oceanic crust is denser/lighter than continental crust
Denser
The lithosphere is:
The mantle and the crust
Asthenosphere:
Upper mantle
Mesosphere:
Lower mantle
Hydrosphere
Water layer and the hydrologic cycle
As a result of lots of pressure, the mantle is:
Almost solid
Where did water on earth come from?
Most of it came from the mantle, but some did come from icy asteroids
Describe the earths magnetic field and outline the advantages of it
It is dipole: convection with the outer core and super rotation of inner core
Protected from the solar wind, including coronal mass ejections
List some life support mechanisms of the earth:
Gravity: keeps gases and water close to surface
Magnetosphere: solar wind protection
Plate tectonics: renews surface water, gases and minerals
Orbit: the Goldilocks zone
Exogenous hazards may include:
Comets asteroids solar flares
Endogenous hazards may include:
Divided into the topographic layers: Lithosphere- earthquakes volcanoes Atmosphere storms bushfires Hydrosphere floods Biosphere disease and animal attacks
The severity of a disaster on a population depends upon:
Quality of living Vulnerability: the ability to mitigate and adapt to changes Infrastructure Economy Government Culture Society
Vulnerability due to climate change:
The susceptibility and inability to cope with the adverse impacts of climate change
Describe the susceptibility of the worlds population to hazards
Most mega cities lie near coastlines, fault lines, volcanoes and are within +/- 20 degrees of equator so they’re in the tropical cyclone belt
Disaster protection plan:
Recognise the hazard Assess the assets ie people, infrastructure exposed to the hazards and their vulnerability Assess the loss Manage the problem: risk mitigation Adapt to the hazard
Effects of climate change
Higher average temperature, higher night minimums, temp spikes, uncertain precipitation, more extreme weather events, sea level rise, salt water inundation of coastal areas
Effects of climate change on agriculture
Decrease crop yield.
What are the ways we could adapt to changes in climate for agriculture
New crop varieties, diversifying farming practices, investment in technology, education and insurance systems
Who are the possible people/ organisations that will implement changes in the way that food is produced?
NGOs, corporations, local/non local drivers.
Many social/political factors come into play
Social/political effects on threats to global food security
Net reduction in food, greater food prices.
Many people can’t grow their food, will be impacted the most
How is the war in Syria an example of how food security threatens national and international relations
Massive drought for a few years. Large scale migration to the cities. Over population, poverty, social conflict, political conflict
Minerals are
Give an example
Chemically homogenous. Exist as crystal lattices, usually inorganic
Diamond, graphite, quartz
Igneous rocks can be both
Intrusive (plutonic) large grain. Formed beneath the earths surface
Extrusive (volcanic) small grain. Formed in volcanoes
List the two types of metamorphic rocks
Contact: physically touching the heat source like magma. Allows minerals to recrystallise in the solid state. NO MELTING
Regional: formed through pressure
Sedimentary rocks are formed by:
An example of a Sedimentary rock is
Erosion
Sandstone
List the seven principles of geology
Uniformitarianism Superposition Original horizontally Lateral continuity Cross cutting relationships Inclusion Faunal succession
Uniformitarianism is
The present is the key to the past. Geological processes have barely changed over time. Can do relative dating
Superposition is
Sedimentary rocks are deposited sequentially. Youngest at the top
Original horizontality
Layers of sediment are deposited horizontally by gravity
Lateral continuity
Rocks that are similar but have been separated or eroded are assumed to be the same
Cross cutting relationships
Rocks being cut are older
Principle of inclusion is
Inclusions are older
Faunal succession principle is
Strata can be dated by the fossils they contain
Eg a dinosaur bone won’t be found in the same strata as a Neanderthal bone
Describe some absolute dating processes
Carbon dating
Tree rings tell you about climate and seasons
Lead isotope dating: told us age of the earth
Zircons are tough minerals, oldest preserved rocks
What is the age of the earth
4.55 Ga
A divergent plate boundary is
A mid ocean ridge
A continental rift
A convergent plate boundary is
A subduction zone
A conservative plate boundary is
A horizontal plate displacement
Lateral movement
Plate tectonics explains: the motion of the ... ... Of the lithosphere ... Formation and dispersal ... Isolation which supports ... Oceanic ... And changes in ... Bi modal ...
Continents Recycling Geographic, evolution Circulation. Climate Hypsometry (measurement of land elevation relative to sea level)
Why does the earth’s core remain hot?
Remnant kinetic energy from accretion (when meteors crashed together to form earth)
Define isostatic equilibrium
When objects of different densities force each other into equilibrium.
For instance: glaciers press into the earth. When they disappear, the lithosphere depresses
How do glaciers form
Continents drift over the poles
Snow remains in the same area year round
More and more snow accumulates
Pressure builds, snow compresses into small sugar like crystals
Milankovic orbital cycles are
Mid term climatic changes that result from the non uniform of the earth about the sun. Climates last for roughly 23 000 years.
Also called astronomical cycles
A decrease in sea level rise may be due to
The formation of glaciers on land
If glaciers form in the ocean, what change is there to sea level elevation?
No change
What are the impacts of glaciers that form on land?
Unique migrations across land bridges as a result of lower sea level
What were the implications of the break up of Antarctica from Australia?
Tethyan oceanic gateway disappeared, warm ocean currents that kept Antarctica warm disappeared. Brought PNG and Australia close to Asia
What is El Niño?
Brings hot dry temperatures in Australasia and unseasonal heavy rain in South America
What is La Niña?
Cooling of the waters in the pacific. Brings cooler wetter climate to Australia
What is Wallace’s line
A line that separates the flora and fauna of Australia and PNG from Asia
Describe the Cambrian
Predation meant the development of exoskeletons eg Trilobites, horseshoe crabs. First land visits by sea scorpions
Define rheology
Involves the strength of a material. The ductility and brittleness
The focal point of an earth quake is the
Hypo centre
The distance from the surface crust to the hypo centre is the
Focal depth
The epicentre of an earthquake
The point on the surface crust directly above the hypocentre
Dynamic or long wave topography does what?
Examines the mantle processes beneath the crust. Measures over several hundred kilometres
Short wavelength topography does what?
Measures distances of only a few kilometres
Modelling used to be what?
Analogue using clay and sand models
Describe a compressional continental fault
Continents are compressed together resulting in brittle failure, or syncline and anticline patterns. Also called reverse faulting
A fault line that has only lateral displacement is called a
Give an example
Strike slip
San Andreas fault
What is an extensional continental fault?
Mantle convection pulls continental crust apart, also called normal faulting. Leads to thinner crust, formation of basins
Name the three types of oceanic faults
Extension
Strike slip
Convergent
Describe a convergent plate boundary and name an implication of this
Also called a subduction zone. Oceanic crust subducts beneath the lighter continental crust
Mantle plumes cause volcanoes
Are oceanic strike slips a tsunami hazard?
No, only lateral movement
Another name for an abandoned or inactive fault line is …
And why is it inactive?
Fracture zone
Both plates now move in the same direction
Why does the age/depth relationship fall apart near continents?
Sediments and erosion
Medium term topography and climate is forced by
Orbital cycles, and atmosphere and hydrosphere feedback mechanisms
Long term topography and climate is forced by
Tectonics and mantle convection
Describe the Hadean period
Molten crust, moon was much closer, few rocks like zircon are preserved
Describe the Archean period
Onset of first continents
Vigorous convection due to greater heat flow. More radioactivity that has decayed now.
Which period in time had the earliest forms of life? Describe this life
Archean. Prokaryote bacteria and stromatolites
When did the ozone layer develop?
Proterozoic, however very thin, little UV protection
What is an extremophile?
An organism living in harsh conditions ie high temperatures, toxic atmospheres.
What is the fundamental requirement for life?
Self replicating DNA
Describe the Proterozoic period
Oxygen in the atmosphere. Cyanobacteria able to photosynthesis. Evidence for single sided plate tectonics
The Proterozoic super continent is called. What was it
Rodinia. Land of Rodinia was entirely barren with no vegetation
Describe the runaway albedo effect in regard to the Proterozoic snowball earth
Ice age. Increases the amount of radiation reflected from the earth’s surface, makes things colder, ice age runs away.
What makes glacial rocks different?
Glacial drop stones. Glaciers grind up rock and pick pieces of it up and drop it in new places
Describe the late Proterozoic
Ediacaran fauna, multicellular organisms with tissues and wide variety of symmetries
Describe the Paleozoic
Complex life, hard shells, fish, arthropods, reptiles evolved. Ended with large mass extinction
Describe the Cambrian
Predation meant the development of exoskeletons eg Trilobites, horseshoe crabs. First land visits by sea scorpions
Describe the Ordovician
Further explosion of life, burrowing animals more common
List the geological time scale in order
Hadean, Archean, Proterozoic, Paleozoic, Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian
Carboniferous
Trees and high oxygen continent, big insects
Devonian
Colonisation of land by trees
Cenozoic
c no dinosaurs, rise of mammals
What is cleavage in regard to minerals
Planes of weakness in the crystal lattice
Do all minerals exhibit cleavage?
No, but they fracture. Most common way is conchoidal
What is the hardness scale?
Is measured by whether a mineral or rock can scratch another surface
How did minerals contribute to the water that exists on earth today?
Minerals such as Ringwoodite contain water. When they are melted in the mantle, the water is released into the atmosphere
Rocks are composed of …?
Minerals
How are intrusive rocks formed?
The slow cooling of magma underground forms large crystals
How are extrusive rocks formed? How does silica content relate to their viscosity?
In volcanoes.
High silica content, the higher the viscosity
Name the various types of sedimentary rocks
Fluvial (river)
Marine (made up of organisms as well as minerals) eg carbonate from shells makes chalk
Describe the lithification of sedimentary rocks
Deposition, compaction, cementation.
What is the cementation of sedimentary rocks
Dissolved material is redeposited in areas of low pressure resulting in cementation
How is porosity in sedimentary rocks important?
Allows movement of water through bed rock
Give an example of a carbonate rock and how it is formed
Limestone. Formed by the deposition of carbonate from organisms that has undergone heat and pressure
List the two types of carbonates that can form
Biogenic (deposition of organisms)
Chemical (accumulation of sediment around a nucleus of sand or other grain)
What is an evaporite?
A chemically precipitated rock. Eg salt
What is regolith?
Soil. Rocks that have undergone weathering and can hold water
What is a fossil?
What are the two types?
The remains or impression of once living plant or animal material
Is hard or soft tissue better preserved in fossils?
Hard
Comment on the ‘colour’ of dinosaurs
Fossils don’t indicate colour. Scientists look at present day melanosomes for colour
Describe paleogeography
Study of geographical features at periods in the geological past. Tells us about the habitat distributions and climate sensitive organisms
Spatial coverage of fossils
Gaps in the fossil record are due to uplift and erosion (tectonism) or non depostion.
Cratonic regions that are exposed do not contain fossils
Describe trace fossils
They preserve the behaviour of animals, like burrows and tracks, often indicate the position of rocks (up or down)
Depth is also indicated by the areas at which organisms lived.
Event Stratigraphy can be used to …
determine the age of rocks and thus define the period of time they were from
Isotope stratigraphy is what?
Dating of strata based on the content of various isotopes of oxygen for instance. Concentration of oxygen 18 decreases with temperature. It is also denser and is found more commonly in oceans. Indicates time periods
What is sequence stratigraphy?
changes in sea level: transgression and regression (rise and fall). Predictable shifts in sedimentation
Define Paleoclimate
A climate that was prevalent at a particular time in the earth’s history
The atmosphere is an ocean of air. Elaborate pls
There is pressure because of weight, eddy currents form clouds around mountains.
Nitrogen is … by biological processes, stopping it from …
Fixed, increasing infinitely
Homosphere is …
turbulent so everything is mixed up. As you cross the turbopause, less turbulence, enter the heterosphere, layers of gases separated by atomic weight
Name the layers of the atmosphere
Trevor: Troposphere Started: Stratosphere Making: Mesosphere The: Thermosphere Eggplant: Exosphere
How do we value the environment?
It does work for us so we value it. For instance soil formation, medicinal resources, gas regulation
The atmosphere is fluid as a result of …
Earth’s systems trying to redistribute heat
What is a Hadley cell? What are the implications?
Atmospheric currents that rise at the equator and fall at about +/- 30 degrees. Increases precipitation. Cool dry air falls. Locations at around 30 degrees north and south of the equator are commonly deserts
What is the Intertropical Convergence Zone
A zone near the equator where north and south air masses converge, creating a low pressure zone
Why is the equator hotter?
It is perpendicular to the sun in the earth’s orbit and is less able to reflect heat like the poles
What is the coriolis effect
an effect whereby a mass moving in a rotating system experiences a force (the Coriolis force ) acting perpendicular to the direction of motion and to the axis of rotation. On the earth, the effect tends to deflect moving objects to the right in the northern hemisphere and to the left in the southern and is important in the formation of cyclonic weather systems.
Describe the difference between homonin and homonid
nin is exctinct, id is modern human
What led to bipedalism in early humans?
Increased aridity in Africa due to growing rift valley and the India eurasia collision thinned out forests, was better to stand up and walk the longer distances
Describe an Australopithicus
Earliest bipedal homonids, smaller brain, now extinct
Homo Habilis was …
Larger brain than australopithicus, use of tools, still small
Homo erectus
Upright man, use of fire
Homo neanderthalensis
Only existed in Eurasia, heavy build, complex society, had a language probably
Homo Sapiens
Modern humans, highest cranial capacity, dominant species on planet, only surviving species of homonin
