Crustal Deformation
Define Deformation
Deformation is defined as a change in location, orientation, shape or volume due to applied stresses (tectonic movements).
What is an earthquake? Where do most earthquakes occur? What plate boundaries have the largest and most frequent earthquakes?
Earthquake: When the stress reaches a critical level (rock strength + friction) the rock fails and breaks along a new or pre-existing fault generating an earthquake (movement). The accumulated energy is released when the fault ruptures as seismic waves (vibrations).
Most earthquakes occur along the boundaries of tectonic plates, where the Earth's lithosphere is under stress due to the movement of these plates.
1. Subduction Zones (Convergent Boundaries): Subduction zones are locations where one tectonic plate is forced beneath another plate into the Earth's mantle. These zones are associated with the largest and most powerful earthquakes on Earth, often reaching magnitudes greater than 9.0.
2. Transform Faults (Transform Boundaries): Transform faults are fractures where tectonic plates slide past each other horizontally. Although they may not produce the largest earthquakes, transform faults are associated with frequent seismic activity due to the buildup and release of stress along the fault lines. (San Andreas Fault)
Define Albedo
percentage of solar radiation reflected off a surface.
Define the water cycle
The water cycle is the continuous movement of water on, above, and below the surface of the earth. It describes how water changes form and moves through different stages.
Define meandering streams and braided streams.
Meandering streams - have a channel that is highly sinuous (curvy).
Braided - consist of a series of intertwined channels that are overloaded with sediment.
Define Stress and Strain
Stress = The force applied across a unit area
Strain = The result of deformation, which is caused by forces acting on rock.
Explain what the hypocenter/focus and epicenter are.
When the accumulated strain energy exceeds the strength of the rocks, it is released suddenly in the form of seismic waves, resulting in an earthquake. The point within the Earth where the energy is released is called the FOCUS or HYPOCENTER, while the point on the Earth's surface directly above the focus is called the EPICENTER.
What is the greenhouse effect?
- BONUS +10pts: Name the major greenhouse gasses.
The warming of Earth’s surface and lower atmosphere that occurs when its own emitted infrared heat is trapped and reradiated downward by greenhouse gases.
Greenhouse gases major players water vapor (H2O), carbon dioxide (CO2), methane (CH4), CFCs and nitrogen dioxide (NO2)
What form is most of Earths water found in? (solid, liquid, or gas)
Solid - ~97% frozen
Includes glaciers/ice caps and ground ice/permafrost
Think about how water velocity in a stream affects the particle’s load. As the velocity of flow decreases would you expect to observe erosion or deposition?
deposition
Describe the types (2) of deformation, what they are dependent on (4) and their outcomes (faulting vs folding).
Types:
1. Brittle - material breaks (DISCONTINUOUS) - FAULTING
2. Ductile - material flows without breaking (CONTINUOUS) - FOLDING
Dependent On:
1. Temperature
2. Pressure
3. Deformation Rate
4. Composition
Describe the different seismic waves. Which waves are the fastest? Which waves cause the most damage? What is the particle motion of each?
Body Waves (P+S waves): Move WITHIN the Earth (faster).
Primary Waves (P-waves):
Secondary Waves (S-waves):
Surface Waves:
What are the 5 processes that affect climate?
1. Albedo
2. Atmospheric Circulation
3. Ocean Circulation
4. Greenhouse Effect
5. Anthropogenic Effect (=humans)
Define porosity and permeability.
1. Porosity - the percentage of rock or sediment that consists of voids or openings.
- Measurement of a rocks ability to hold water
- Lose sand has ~30-50% porosity
- Compacted sandstone may only have 10-20% porosity
2. Permeability - the capacity of a rock to transmit fluid through pores and fractures.
- Interconnectedness of pore spaces
- Most sandstones and conglomerates are porous AND permeable
- Granites, schists, unfractured limestones are IMPERMIABLE
What is a drainage divide?
highland or ridge that separating two drainage basins.
1. Compression
2. Tension
3. Shear
1. Compression
a. Reverse Fault (dip > 35 deg)
b. Thrust Fault (dip < 35 deg)
2. Tension
a. Normal Fault
3. Shear
a. Strike-Slip Faults (left-lateral + right-lateral)
Explain how earthquakes occur in terms of stress.
Compression: Compression stress occurs when tectonic plates collide or converge against each other. This type of stress pushes rocks together, causing them to deform and accumulate strain energy.
Tension: Tension stress occurs when tectonic plates move away from each other, creating extensional forces that stretch and pull rocks apart. This stress can lead to the formation of faults and fractures in the crust.
Shear: Shear stress occurs when tectonic plates slide past each other horizontally in opposite directions. This type of stress causes rocks to move sideways along faults, accumulating strain energy as they resist movement.
Explain positive and negative feedback loops within the climate system + include an example of each.
Positive feedback within the climate system amplifies changes initially caused by external factors.
Water vapor has important positive feedback in climate system. Warmer climate holds more water, increased greenhouse effect traps more heat and warms climate.
Negative feedback mutes or suppresses the initial changes.
Aquifer = body of saturated rock or sediment through which water can move easily
Confined Aquifer:
- completely filled with water under pressure (hydrostatic head)
- separated from surface by impermeable confining layer (aquitard)
- very slowly recharged
Unconfined Aquifer:
- has a water table, and is only partly filled with water
- rapidly recharged by precipitation infiltrating down to the saturated zone
What is the difference between competency and capacity?
The competence of a stream refers to the maximum particle size it carries.
The capacity of a stream refers to the total quantity of sediment it can carry.
Describe what Anticlines and Synclines are and the three parts (features) found within them.
Features found within Anticlines and Synclines:
1. Hinge - Portion of maximum curvature on a fold
2. Limb - Less curved "sides" of a fold
3. Axial plane - Imaginary surface defined by connecting hinges of successively nested folds.
Anticline - arch (hinge on top + limbs pointing down) (looks like an A)
Syncline - trough (hinge on bottom + limbs pointing up) (looks like a U)
Earthquakes can be described by either intensity or magnitude, define the different earthquake scales.
Intensity Scales:
Magnitude Scales:
How can we use geologic proxies (e.g. ice core, deep sediment cores, C and O isotopes, etc.)
to learn about past climatic events?
Bubbles trapped in ice cores preserve the chemical composition of the atmosphere at the time the ice formed. Ice cores contain annual layers that can be readily dated.
Oxygen isotope ratios indicate the temperature of past environments. Two oxygen isotopes are used: 16O and 18O. 16O water evaporates faster than 18O water. 18O/16O is preserved in shells and glacial ice.
What is geothermal energy?
Geothermal energy is produced using natural steam or superheated water.
- No CO2 or acid rain are produced (clean energy source)
- Some toxic gases given off (sulfur compounds)
- Can be used directly to heat buildings
- Superheated water can be very corrosive to pipes and equipment
What types of sediment are transported by rivers? Define them.
Dissolved - minerals in solution
from chemical weathering
Suspended - small rock pieces held
aloft by turbulence
Bed load - coarse material dragged
by traction or rolled/bounced by
saltation