Midterm Flashcards
How do you calculate doubling time of population?
D=70/annual growth rate
What is exponential growth?
Quantity grows at a rate directly proportional to its present size
What is carrying capacity?
Maximum number of people that can live on earth without causing environmental degradation
What is sustainability?
A model of development that ensures that future generations have equal access to earth resources
What are examples of unsustainable management of resources?
overpopulation, land clearing, deforestation, land degradation, wars, geographic isolation
What is the Gaia hypothesis and who proposed it?
Earth is analogous to a living organism; John Lovelock
What is the core made of and how dense is it?
solid inner and liquid outer, density= 10.7g/cm3
What is the mantle made of and how dense is it?
Silicates of iron and magnesium, density= 4.5g/cm3
What is oceanic crust made of and how dense is it?
Composed of basalt, density= 2.9g/cm3
What is continental crust made of and how dense is it?
Granite; density= 2.8g/cm3
What are the main differences between the lithosphere and asthenosphere?
Lithosphere is a cool and rigid outer shell and comprised of the upper mantle and the crust. Asthenosphere is the soft and weak inner.
How thick is the oceanic crust?
~7km
How thick is the continental crust?
~40-70km
What is the significance of the asthenosphere?
It’s where convection happens because it behaves plastically
What does the asthenosphere have to do with the seafloor spreading theory?
Convection forces new buoyant material from the asthenosphere into the mid ocean ridges where the plates are pulling apart
Who proposed the seafloor spreading theory?
Harry Hess in 1962
What is the continental drift theory?
Continents used to fit together like a jigsaw puzzle
Who proposed the continental drift theory?
Alfred Wagner in 1915
When did Pangea break apart?
~200 million years ago
What is a convergent plate boundary?
Plates move towards each other
What is a divergent plate boundary?
Plates move away from each other
What is a transform plate boundary?
Plates slide past each other
What landform is associated with transform boundaries?
San Andreas fault
What landform is associated with divergent boundaries?
midoceanic ridge
What landforms are associated with convergent boundaries?
Mountain ranges, volcanoes, subduction zones
What are the 3 most abundant elements in Earth’s crust?
oxygen, silicon, aluminum
What are the most abundant rock-forming minerals?
Silicon and oxygen
What are some examples of igneous rocks?
Basalt, Andesite, Granite
What are some examples of sedimentary rocks?
Sandstone, Limestone, Chalk
What are some examples of metamorphic rocks?
Slate, Gneiss, Quartzite, Marble
What is the most prevalent volcanic rocks at midoceanic ridges?
Basalt
What are clastic sedimentary rocks?
Rocks formed from the compaction and cementation of discrete fragments and particles
What are non-clastic sedimentary rocks?
Rocks formed from the deposition of dissolved matter through a chemical and/or biochemical process
What is the most important carbonate mineral?
Calcite is the major constituent of limestone and marble
What is marble?
A non-foliated metamorphic rock that comes from limestone
What are faults?
Fractures accompanied with displacement
What are joints?
Fractures without displacement
What are synclines?
bowl shaped concave folds
What are anticlines?
Arch shaped convex folds
What is superposition?
Rock beds near the top are younger and the oldest materials are at the bottom of the strata
What is original horizontality?
individual beds were nearly horizontal when they were deposited, tilting and development of a fracture line
What is the difference between the epicenter and hypocenter?
The hypocenter/depth of focus is the point within the earth where the waves originate, and the epicenter is the location on the earths surface directly above the focus
What is the relationship between depth of focus and severity of damage caused by an earthquake?
A deep earthquake has farther to travel and is less destructive. A shallow earthquake is more destructive.
What is a seismograph?
The instrument that records the details of seismic activity.
What is a seismogram?
The written or digital record of seismic activity.
What is an R wave?
Surface waves; much slower than S and P waves
What are S waves?
secondary/shear waves that propagate at ~3km/sec
What are P waves?
primary waves that are fast (>5.5km/sec) and associated with sounds
What is the Mercalli scale?
Intensity of shaking, determined by amount of damage
What is the Richter scale?
The amount of energy released at the point of rupture
What’s the most powerful earthquake recorded since the 1900s, and what was its magnitude?
Chile, 9.5
What are the characteristics of a tsunami in the deep ocean?
Small, fast moving waves (>500kmh) that are < 1m in height and spaced long distances apart
What are the characteristics of a tsunami as it approaches the shoreline?
The waves slow to about 45kmh, and the space between waves is decreased, which increases the height.
What is magma?
Molten rock beneath the Earth’s surface, in the crust or upper mantle, at depths ~50-250km.
What is lava?
Magma that has emerged from the Earth’s surface.
What is lahar?
A mixture of pyroclastic debris and water
What type of plate boundaries are most commonly associated with volcanoes?
Convergent
Where are shield volcanoes found?
Oceanic crust
What are two examples of Strato-volcanoes?
Mt St Helens and Mt Fuji
Where is Mt St Helens located and when was its last major eruption?
Washington; May 18, 1980 after 120 years of dormancy
What impact did the eruption of Mt Pinatubo in 1991 have in the global climate?
Global cooling; summer was 0.5C cooler
Why was the death toll following the eruption of Mt Pinatubo relatively low?
Pre-eruption warnings
What gas is associated with the Lake Nyos disaster in 1986?
Carbon dioxide
What is pyroclast?
Materials that are ejected from the volcano: ash, cinders, bombs
What are ash flows?
Lava that escapes violently as a glowing avalanche of hot gas and incandescent ash
What is gypsum found in?
Drywall
What is the concentration factor?
The ratio of necessary ore concentration for profitable mining to its average concentration in Earth’s crust
What is itai itai?
A chronic disease found in the Zintsu river basin due to heavy mineral waste dumping (zinc, lead, and cadmium)
