Week 5: Glaciation, Earth Structures, Solar System Geology Flashcards
What is the equation for ‘compressive strain’?
(usually negative)
(Length of deflection - OG Length) / OG Length
Where do oceanic mafic lava flows typically occur?
Divergent plate boundaries where rapid cooling of magma occurs and new ocean floor is formed.
What is the difference between ‘compaction compression’ and ‘distortion’?
Compaction compression: uniform pressure placed on the object/material from all directions, shrinking it.
Distortion: pressure is placed in the vertical or horizontal direction, distorting it.
Describe ‘crystal deformation’.
Under direct pressure from tectonics, atoms can move slowly within a solid to create shortening in one direction (the source of foliation in rocks).
Describe elastic, brittle, and ductile deformation.
Elastic: recoverable deformation.
Brittle: deformation that causes fractures.
Ductile: permanent deformation (no breaking).
Describe the ‘dip’, ‘dip direction’, and ‘strike’.
Dip: steepest angle or inclination from the horizontal to the desired plane.
Dip direction: direction in which the inclined plan points from the strike.
Strike: perpendicular to the dip (or the DIP is perpendicular to the STRIKE).
What two factors play a key role in the deformation of rocks and other materials?
Temperature and pressure.
Ductile deformation = high temp. and pressures (high-grade metamorphism).
Brittle fractures = low temps. and pressures (near the surface)
Describe the anatomy of a fold (four key components)
- Axis (crest of a fold)
- Plunge (if applicable, the inclined axis)
- Axial plane (which divides the fold as symmetrically as possible)
- Limbs (two sides of a fold on either side of the axial plane)
What are the two types of folds?
- Anticline (with older material underneath)
2. Syncline (with newer material on top)
How do domes and basins occur?
Caused by 3D foliation of anticlines and synclines.
Differentiate between a ‘strike-slip’ and a ‘dip-slip’ fault.
Strike-slip: fault caused by brittle shearing of tectonics (occurs parallel to the strike of the fault).
Dip-slop: main deformation occurs on dip direction of fault. ‘Normal’ dip-slip fault means the hanging wall comes down, while ‘reverse’ dip-slip fault means it comes up.
Differentiate between a ‘graben’ and a ‘horst’.
Sort of like anticline and syncline: graben is the LOWERED body of rock in a fault, while a horst is the RAISED body of rock.
What are ‘joints’? Describe their significance.
Fractures in rock that result from brittle deformation (typically no displacement).
- Chemical weathering concentrated along joints
- Mineral deposits are emplaced along joints
- Represent risk to construction projects
What is one way in which joints may be formed?
Water seeps and settles in the fractures of joints, freeze in the winter time, and expand, further cracking the rock open.
List the two continental ice sheets,
Greenland and Antarctica.
The Pertio Moreno Glacier (Argentina) spans _____ km with a width of _____ km.
The Pertio Moreno Glacier (Argentina) spans 28km with a width of 2km.
Describe the process of the formation of glacial ice.
- Snowflakes accumulate into granular snow
- Air is forced out
- Snow recrystallizes into a denser mass called a ‘firn’
- At 50m depth, firn fuses into a solid mass of interlocking crystals.
What are three ways in which a glacier may move?
- Internal deformation (occurs within the ice)
- Basal slip (entire mass slipping)
- Meltwater (hydraulic jack, lifting ice to move over rock)
What are the ‘zone of accumulation’ and ‘zone of ablation’ of a glacier?
Zone of accumulation: where a glacier forms and grows
Zone of ablation: where there is a net loss of the glacier
What is an ‘erratic’?
A large body of rock that was transported by a glacier.
_____ produces rock flour and glacial striations, and occurs when a glacier grinds against rock like sandpaper.
ABRASION produces rock flour and glacial striations, and occurs when a glacier grinds against rock like sandpaper.
The bright blue colour of Lake Louise is caused by:
Glacial rock flour, very fine sub-sized powder ground off land.
List three examples of landforms created by glacial erosion.
- Glacial trough (U shaped, deepening/widening/straightening)
- Hanging valleys
- Cirque (head of the glacier, forms wide crevice)
- Tarn (the lake in a cirque)
- Arete (sharp ridge)
- Horn (pyramid mountain, like the one in Switzerland)
- Spur (triangular cliff)
List an example of a landform created by glacial erosion.
- Roche moutonnees (asymmetric bedrock knobs with steep sides indicating direction of ice movement)
- Fjord (water-filled glacial trough along a coast)
What is till? Differentiate between ‘lodgement’ till and ‘ablation’ till.
Material deposited directly by glacial ice.
Lodgement till = compacted till plastered down by ice. Low permeability, uniform in nature, difficult to excavate.
Ablation till = loose piles of debris, cohesionless and easier to excavat, high permeability.
List two examples of landforms made of till.
- Lateral/medial /end/ground moraines (ex. Oak Ridges Morain, which is currently located under a large part of Ontario and is the source of much of the province’s groundwater)
- Eskers (Aretes that have formed trailing hills, tunnels, etc)
- Drumlins (pieces of bedrock interrupt sediment flow, ice moves over bedrock)
- Glacial deposits/outwash (anything that doesn’t become part of a landform)
Slightly more than __% of the world’s water is tied up in glaciers.
2%
If the Antarctic ice sheet melted, sea levels would rise ___m. If the Greenland ice sheet melted, sea level would rise ___m.
60m, 6m
Major glacial stages occurred during the __________ Epoch, _____ years ago.
Major glacial stages occurred during the PLEISTOCENE Epoch, 18,000 years ago.
What theory touches on the causes of Ice Ages? What are its postulates?
The Milankovitch hypothesis states that ice ages are caused by:
- Variations in shape of Earth’s orbit over 100,000 years (eccentricity)
- Angle of Earth’s axis changes (obliquity)
- Earth’s axis wobbles (precession)
The increase in carbon emissions is warming the earth at a rate ____ times faster than Earth has seen through natural swings.
100 times faster.
Which theory supports the most widely-accepted view of how our solar system formed?
The Nebular Hypothesis.
Solar system coalesces out of dust cloud remains produced by earlier supernovae.
How long ago was the Hadeon eon, and what significant events occurred during this time period?
Hadeon Eon (4.6 - 4 bya)
- Earth congeals
- Unstable crust forms
- Iron is pilled to the core
- Moon forms
Why does the sun not collapse in on itself?
- Sun is held together by gravity, but pulled apart by internal gas pressure
- Fusion occurs (H to He)
- If pressure was turned off, sun would collapse in less than 1/2 hour
What is the cause of the sun’s complex magnetic field?
Different layers of the sun spin at different rates, which prevents a uniform magnetic field.
What protects Earth from solar flares, and where does this source of protection come from?
Earth’s magnetic field - caused by Earth’s iron core and the liquid mantle surrounding it.
We are __________ years overdue for a magnetic field reversal.
300,000 years
Mercury rotates every _____ days and orbits the sun twice during every _____ rotations.
Mercury rotates every 58.65 days and orbits the sun twice during every THREE rotations.
Surface collapse/shrinkage and the presence of a magnetic field on mercury indicates…
There is likely tectonic movement and a partially liquid core.
There is evidence of tectonic movement on Venus due to the presence of…
- strike-slip faults
- contractile folding
- extension fractures
What evidence do we have to show that Mars used to have a magnetic field?
Used to have a liquid core because parts of the crust are magnetized, like on Earth!
The formation of stupendously large mountains and volcanoes on Mars can be characterized by…
The absence of tectonics (mounds will keep growing, but will not erupt, so nothing to show for it)
What is the cause of Jupiter’s strong magnetic field?
Mantle composed of metallic hydrogen, e’s are free to move however they want, so both the core and the mantle are huge conductors.
What are the four Galilean moons [of Jupiter]?
Io (most volcanic activity in the solar system)
Europa (crust made of ice, possibly water underneath)
Ganymede
Callisto
_____ is the biggest of Saturn’s 82 moons.
Titan (huge candidate for housing archeaen life).
Around Uranus, moons orbit _____.
Vertically
Pluto contains mountains of _____ and glaciers of _____.
Pluto contains mountains of WATER/ICE and glaciers of METHANE/NITROGEN.
What are some factors that omit Pluto as a planet?
- Pluto does not orbit the sun directly like other planets.
- It has not cleared the neighbourhood around its orbit (which render it a dwarf planet)
- One cannot decipher between Pluto and its moon (same size)
