Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
50 Cards in this Set
- Front
- Back
|
• What causes (or drives) metamorphism?
|
o Heat – causes chemical changes which result information of new minerals and release of water- increases grain size
o pressure – causing largely textured changes such as alignment of minerals o fluids |
|
|
• What are the two textures developed in metamorphic rocks? What is a foliation?
|
o Foliated and nonfoliated
o Foliation- alignment of minerals caused by an external force (pressure or stress) |
|
|
• Understand ideas behind contact and regional metamorphism
|
o Contact metamorphism –changes in rock caused by the heat from a nearby magma body
o Regional metamorphism – metamorphism associated with large-scale mountain building – during these dynamic events large segments of earth’s crust are intensely deformed along convergent plate boundaries |
|
|
• What are P waves? What are their main characteristics (i.e. type of motion, velocity relative to other waves, materials they travel through)?
|
o P waves = primary waves – “push-pull” waves they push (compress) and puss(expand) rocks in the direction the wave is traveling
o Solids liquids and gases resist a change in volume when compressed and will elastically spring back once the fore is removed |
|
|
• What are S waves? What are their main characteristics (i.e. type of motion, velocity relative to other waves, materials they travel through)?
|
o S waves – secondary waves – “shake” the particles at right angles to their direction of travel
o Gases and liquids do not respond elastically to changes in shape they will not transmit S waves |
|
|
• Seismic wave velocity changes as waves travel through the Earth’s interior. How are these changes in velocity commonly explained?
|
o The velocity of seismic waves increases with depth. In addition waves travel faster when rock is stiffer or less compressible.
|
|
|
• What are Earth’s different shells based on composition? What are Earth’s different shells based on physical properties?
|
o Mantle = silicate mineral, rich in iron and magnesium, hot and capable of flow, ultramafic rocks,
o Outer core- liquid, iron and other elements o Inner core – very dense, solid with iron and some nickel, very small, rotates faster than the mantle and outer core |
|
|
• Where does the magnetic field originate?
|
o Outer core
|
|
|
• What is continental drift hypothesis?
|
o Credited to Alfred Wegener, suggested all present continents once existed as a single supercontinent, around 200 million years ago the supercontinent began breaking into smaller continents, which then “drifted” to their present positions
|
|
|
o What evidence was used to support the continental drift hypothesis?
|
Continents fit together like a puzzle
Distribution of fossils across the southern continents, Continuous mountain chain from north american the way to Scandinavia where rocks are similar in age and share a common geologic history Climate evidence, rocks forming during the ice ages are continuous throughout Gondwanland |
|
|
• What is the sea floor spreading hypothesis
|
o The hypothesis first proposed in the 1960s by harry hess, which suggested that new oceanic crust is produced at the crests of mid-ocean ridges which are the sites of divergence
|
|
|
• What plate boundaries exist? What are divergent plate boundaries? What are convergent plate boundaries? What are transform plate boundaries?
|
o North American , south American, pacific, African, Eurasian, Australian- Indian, Antarctic
o Divergent plate boundaries –where 2 plates move apart, resulting in upwelling of material from the mantle to create new seafloor o Convergent – where 2 plates move together, resulting in oceanic lithosphere descending beneath an overriding plate, eventually to be reabsorbed into the mantle or possibly in the collision of 2 continental blocks to create a mountain system o Transform – where 2 plates grind past each other without the production or destruction of lithosphere |
|
|
• What is a passive continental margin?
|
A margin that consists of a continental shelf, continental slope, and continental rise. They are not associated with plate boundaries and therefore experience little volcanism and few earthquakes
|
|
|
• What is the Hawaiian island hotspot?
|
o An area of volcanism, high heat flow, and crustal uplifting that is a few hundred kilometers across. As the pacific plate moved over this hot spot successive volcanic structures were built
|
|
|
• How fast do plates move? How do we know?
|
o 9 cm or 4 inches per year
o A fixed position of the hot spot in the mantle |
|
|
• What drives plate motions
|
o Slab pull – occurs because old slabs of oceanic lithosphere are more dense than the underlying asthenosphere and hence “sink like a rock”
o Ridge push- gravity driven mechanism results from the elevated position of the oceanic ridge, which causes slabs of lithosphere to “slide” down the flanks of the ridge |
|
|
• Where are most of the volcanoes located?
|
o Most volcanoes are located along margins of the ocean basins – most notably within the circum-Pacific belt known as the Ring of Fire.
o Along ridges where there are tectonic plates. |
|
|
• What controls the style of volcanic eruptions? What is viscosity? What controls viscosity?
|
o Viscosity – resistance of a fluid to flow
o Magma – silica content o Temperature – hot = lower viscosity cold – higher viscosity o Controlled by composition temperature and amount of dissolved gases o Basalt is non- explosive, andesite is intermediate and rhyolite is very highly explosive |
|
|
• What are shield volcanoes?
|
o A broad, gently sloping volcano built from fluid basaltic lavas
o Most have grown up from the deep ocean floor to form islands or seamounts o Ex. Hawaii, Galapagos and Iceland o Some occur on continents |
|
|
• What are stratovolcanoes (or Composite cones
|
o A volcano composed of both lava flows and pyroclastic material
o Most are located along the ring of fire o Large, nearly symmetrical structure, gas rich magma having and andesite composition |
|
|
• What are pyroclastic flows and lahars?
|
o Pyroclastic = a highly heated mixture, largely of ash and pumic fragments traveling down the flanks of a volcano or along the surface of the ground
o Lahar = debris flows on the slopes of volcanoes that result when unstable layers of ash and debris becomes saturated and flow down slope, usually flowing stream channels |
|
|
• How do calderas form?
|
o 1. The collapse of the summit of a large composite volcano following an explosive eruption of silica- rich pumice and ash fragments - crater lake type
o 2. The collapse of the top of a shield volcano caused by subterranean drainage from a central magma chamber – Hawaiian type o 3. The collapse of a large area, caused by the discharge of colossal volumes of silica- rich pumice and ash along ring fractures – Yellowstone type |
|
|
• What types of stress exist
|
o Differential stress – when stress is applied unequally in different directions –
o Compressional stress- differential stress that shortens and thickens the rock body by folding, flowing, and faulting o Tensional stress- plates are being rifted apart ( divergent plate boundaries) tends to lengthen rock bodies located in the upper crust |
|
|
• What is meant by brittle vs. ductile deformation behavior
|
o Brittle – rocks near the surface tend to behave like a brittle solid and fracture once their strength is exceeded
o Ductile – a depth where temperatures and confined pressures are high, rocks exhibit ductile behavior; solid-state flow that produces a change in the size and shape of an object without fracturing |
|
|
• What are synclines? What are anticlines
|
• What are synclines? What are anticlines
|
|
|
• Know the basic about faults
|
Faults = fractures in the crust along which appreciable displacement has taken place
Hanging wall- rock surface that is immediately above fault Footwall- rock surface that is below the fault |
|
|
o What are normal faults and what type of stress do they accommodate?
|
Dip slip fault:
When hanging wall block moves down relative to the footwall block Steep dips: Tensional stress Divergent plate boundary |
|
|
o What are reverse faults and what type of stress do they accommodate?
|
Hanging wall works up with respect to footwall
Compressive stress Convergent plate boundary |
|
|
o What are strike-slip faults and what type of stress do they accommodate?
|
Transform plate boundary
Shear stress |
|
|
• What is an earthquake? What are the focus and epicenter? Why is the depth of the focus important with respect to damage/shaking?
|
o Vibration of earth produced by the rapid release of energy
o Focus – the zone within earth where rock displacement produces an earthquake o Epicenter- the location on earth’s surface that lies directly above the focus of an earthquake o More shallow = more damage o Deeper= less damage |
|
|
• What are Surface waves and what are their main characteristics?
|
o Surface waves – travels along the other part of earth
o Travel along the ground – cause ground and anything resting upon it to move o Up and down motion and also have a side to side motion |
|
|
• What is elastic rebound? How does this relate to earthquakes and behavior of rocks?
|
o The sudden release of stored strain in rocks that results in movement along a fault
o Most earthquakes are caused by elastic rebound and earthquakes occur mostly along faults |
|
|
• What factors control the damage due to shaking?
|
o Magnitude of the earthquake and its proximity to a populated earth
o Intensity, duration of vibrations, nature of the material upon which the structure rests, and design of the structure |
|
|
• What is the Mercalli Intensity scale? What is the Moment Magnitude scale? How is each determined?
|
o Mercalli = a 12 point scale developed to evaluate earthquake intensity based on the amount of damage to various structures
o Moment = a more precise measure of earthquake magnitude than the richter scale that is derived from the amount of displacement that occurs along a fault zone |
|
|
• Where is the New Madrid seismic zone?
|
o Most active seismic zone in North America, spans across Kentucky, Tennessee, Arkansas, Missouri and surrounding areas.
|
|
|
• What is mass wasting?
|
o The downslope movement of rock, regolith, and soil under the direct influence of gravity
|
|
|
• Where is mass wasting most common?
|
o In areas of rugged, geologically young mountains
|
|
|
• What is the main controlling factor of mass wasting?
|
o gravity
|
|
|
• What other factors can contribute to or trigger mass wasting? How/why can these secondary factors contribute to mass wasting
|
o Water – heavy rains or periods of snowmelt saturate surface materials
• When pores in sediment become filled with water the chohesion among particles is destroyed allowing them to slide past on another o Oversteepened slopes – stream undercutting a valley wall or waves pounding against the base of a cliff • They become unstable o Removal of vegetation – plants protect against erosion and contribute to the stability of slopes because their root systems bind soil and regolith together • Shield the soil surface from erosion , when vegetation is removed by people or forest fires surface materials frequently move down slope • Fire can make soil dry and loose it can also bake the ground creating a water-repellant layer at a shallow depth |
|
|
• Where is most of the water on the planet stored? How much of the total water is freshwater?
|
• 97.2 % is stored in global oceans
• Fresh water 2.8% is fresh water |
|
|
• Why are rivers (running water) important?
|
o Use them as highways for moving goods, sources of water for irrigation and energy, fertile floodplains
|
|
|
• What is a drainage basin?
|
o The land area that contributes water to a stream
|
|
|
• How does the river system change from the headwaters to the mouth?
|
o Rivers may begin as headwater streams that flow from hillsides, wetlands, lakes and as melt water from glaciers and snowpack. Headwater streams seek lower ground and join other streams to form larger streams that in turn join others, eventually to form one river channel at its mouth
|
|
|
What are the three main parts of a river system?
|
o a zone of erosion – erode channels in which they flow
o a zone of sediment transport – transport materials provided by weathering and slope processes o a zone of sediment deposition – produce a wide variety of erosional and depositional landforms |
|
|
• What is meant by headwaters and mouth of a stream
|
o The point downstream where a river empties into another stream or water body
|
|
|
• What is laminar vs. turbulent flow?
|
o Slow moving stream is a laminar stream and the water particles move in roughly straight-line paths that parallel the stream channel
o Stream flow that is usually turbulent with the water moving in an erratic fashion that can be characterized as a swirling motion is turbulent flow |
|
|
• What factors control flow velocity?
|
o What is the stream gradient?
• The slope of a stream channel expressed as the vertical drop of a stream over a specified distance o What is discharge? Why is discharge not constant throughout the year? • The volume of water flowing past a certain point in a given unit of time • Variables as rainfall and snowmelt |
|
|
• How do the gradient, discharge, and channel size change from upstream to downstream?
|
o Observations and measurements must be made.
o Humid regions discharge increases toward the mouth |
|
|
• How can streams erode (transport weathered) material?
|
o Enhanced by water volume
o The force of running water swiftly erodes poorly consolidated materials on the bed and sides of a stream channel |
|
|
• What are meanders and oxbow lakes and how and why do they form? What are cut banks and point bars?
|
o Meanders – a loop-like bend in the course of a stream
o Oxbow lake –a curved lake produced when a stream cuts off a meander. Formed because gradually the neck of the meander erodes and cuts off the old meander which forms the oxbow |
