Short Answer Questions Flashcards
(31 cards)
Transform plate boundaries are __________ because they do not involve creation or destruction of lithosphere.
conservative
List at least three observations that are explained by the theory of plate tectonics.
- the age of oceanic crust increases when you move away from mid-ocean ridges (youngest crust)
- earthquakes and volcanoes are concentrated along plate boundaries
- there are deep ocean trenches along continental margins and island chains
Explain the earthquake depth/distribution pattern seen at subduction zone plate boundaries (can be done in 1-2 sentences)
Along subduction zone plate boundaries, earthquakes are concentrated along the subduction zone (in a chain) and vary in depth but produce many deep earthquakes.
If oceanic lithosphere has relatively uniform composition, explain how one piece of oceanic lithosphere can subducted between another piece of oceanic lithosphere. (this will almost certainly appear on one of the exams!)
the heavier and older plate will dive beneath the less dense (younger) plate and sink into the mantle
oceanic lithosphere is more dense then continental lithosphere
List and briefly define the five criteria for a substance to be considered a mineral.
To be classified as a mineral, the substance has to be solid, naturally occurring (made geologically), inorganic, have a crystalline structure (lattice arranged atoms), and have a definable chemical composition (chemical formula present).
List the sequence of minerals and change in magma composition you would expect during fractional crystallization (Bowen’s reaction series).
Mafic: Olivine, Pyroxene
Intermediate: Pyroxene, Amphibole, Biotite
Felsic: Biotite, Quartz, Muscovite, K-feldspar
If continous, Plagioclase can be any composition but Changs to K-feldspar in low temperature
Briefly describe clastic sedimentary rock texture (grain size, roundness, sorting) as a function of the two following factors:
1) sediment transport distance (i.e., distance from source)
2) energy of depositional environment
- Closer to the source: large gain size, less round, and very poorly sorted
- Farther from the source: small grain size, more round, and very well sorted
- high energy environment (fast river and oceans): large grain size, round sediment, and poorly sorted
- low energy environment (lakes and swamps): small grain size, angular sediment, and well sorted
List the complete sequence of metamorphic rocks you would expect to form from a shale
or mudstone that experiences increasing metamorphic grade in a continent-continent collision zone.
clay, chlorite, quartz, muscovite, biotite, garnet, staurolite, kyanite, sillimanite
What are hotspots and how do they form?
Hotspots are an area of the mantle that is hotter than the rest of the mantle. They form above mantle plumes when the plumes hit the base of the lithosphere and melt.
Why does felsic magma usually generate more explosive eruptions than mafic magma?
felsic magma is more viscous (more silica content) and able to trap more gases
How do calderas form?
When a magma chamber completely empties and the volcano collapses inside of it
What happened in Lake Nyos, Cameroon that caused nearly 2,000 fatalities?
A mass quantity of volcanic carbon dioxide released from a late and concentrated near the ground.
List as many factors as you can that contribute to how deadly or destructive an earthquake is.
magnitude, depth, population density, local topography, and building construction
List as many factors as you can that contribute to how deadly or destructive a volcanic eruption is.
volcano type, eruption style, explosivity index, magnitude, population density, lava flows, lahars, tsunamis, and gas emissions
List and describe all the earthquake hazards that a community located on the coast of a poor country might face.
The community can experience tsunamis, challenging rescue and recovery, and building collapse.
What are cratons and how do they form?
Cratons are cold, relatively stable continental lithosphere (large unheated continents) that are formed by accumulating various types of rocks and the buildup of continental crust.
What are the causes, consequences, and evidence for the Great Oxygenation Event between 2.4 Ga and 1.8 Ga?
The cause of the event was more oxygen production than rock/ocean absorption due to the origin of photosynthetic life. The consequences were a decrease of oxygen in the atmosphere and biotic evolution. The evidence for this event was the appearance of red sedimentary rocks that were oxidized.
What is the most accepted explanation for the end Permian extinction? What type of geological phenomenon?
The most accepted explanation is the Siberian Traps flood basalt eruptions. this geological phenomenon is a hot spot.
What is the most accepted cause for the K/Pg extinction? What is the evidence, and what were the consequences?
The most accepted cause is a meteorite impact. The evidence is the Carter in the Yucatan Peninsula and the consequences were sun blockage and acid rain.
List and describe the four (or five) major trends exhibited by the Keeling curve.
1) the carbon dioxide concentration is increasing
2) the rate of carbon dioxide emissions is increasing
3) the annual cycle of carbon dioxide decreases in the summer and increases in the winter
4) the amplitude of biosphere flux is increasing
What is a tipping point in the context of global climate? Give a real-world example.
A tipping point is a small change in external conditions that can lead to significant environmental and climate impacts. One example of this is the ice melting in the arctic and antarctic can lead to sea-levels increasing.
List and define the four main types of reactions involved in chemical weathering.
- solution reactions: dissolving solid materials in naturally formed acids
- oxidation reactions: “rusting” through electron donations
- hydration reactions: combining minerals with water
- hydrolysis reactions: water molecules breaking chemical bonds
You probably knew this one was coming: list the five factors of soil development and
describe how each of them influences soil development, including the presence/absence
and thicknesses of the four major soil horizons.
- Climate: high temperatures and moisture can speed up the weathering process and development of soil horizons
- Organic activity: earthworms and bacteria add organic matter composition and plant roots that break rocks can add organic matter
- Relief: a sloped terrain can lead to erosion of soil while flat land can produce more organic material
- Parent material: different types of parent material affects nutrient content in the soil
- Time: the longer soil takes to weather, the more developed it is and the more defined its horizon is
List a mineral that is susceptible to chemical weathering, the type of chemical reaction it
undergoes, and the product of that weathering reaction.
A mineral susceptible to chemical weathering is feldspar that undergoes a hydrolysis reaction to produce clay
