MIDTERM HIGHLIGHTS Flashcards
ENDOGENIC
Geological processes that
originate inside of the earth’s crust.
(volcanism, plate tectonics, earthquakes, etc.)
EXOGENIC
Geomorphic processes that
originate at or near the earth’s surface.
(Mass wasting, weathering, erosion and deposition of
materials by fluvial, glacial, coastal, aeolian
processes)
THE TAGEDY OF THE COMMONS
Overconsumption of a shared resource (the Commons) results from individuals acting in
their own best interest.
Benefits go to the individual, but costs go the community
THE FIVE MINERALS THAT MAKE UP GRANITE
- QUARTZ
- ORTHOCLASE
- PLAGIOCLASE
- AMPHIBOLE
- MICA (BIOTITE, MUSCOVITE
FELSIC:
Feldspar + Silica
Light Colored
MAFIC:
Magnesium + Ferric (Iron)
Dark Colored.
PYROCLASTICS
a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases.
Intrusive (Plutonic) Igneous Rocks
Intruded by depth, exposed by erosion.
Magma cools slowly = large crystals.
Extrusive/Volcanic Igneous Rock
Extruded lava at surface and pyroclastic.
Lava cools rapidly = fine-grained crystals
SILLS & DYKES
Sills and dykes are formed when magma intrudes into rock.
Sills form where magma intrudes between layers, they run parallel to the layer.
Dykes form when magma intrudes into a rock along lines of weakness such as fractures and fissures.
PAHOEHOE
Is lava that in solidified form is characterized by a smooth, billowy, or ropy surface
AA
Is lava that has a rough, jagged, & spiny surface.
SILICA CONTENT
Controls how explosive a volcanic eruption will be.
The more silica, the greater the viscosity
SHIELD VOLCANO
Largest volcanoes. Formed from basalt. Gentle slope (5o - 12o).
Lava flows quickly and over great distances. Lava rivers and lava tubes common.
Some damage to infrastructure, not usually associated with loss of life.
CINDER CONE VOLCANO
A small volcano cone built of dry pyroclastic material of various size.
Smaller in size and shorter life span.
CALDERA VOLCANO
Volcanic eruption causes collapse of the cone into the magma chamber below and
collapse of a stratovolcano.
Calderas are some of the largest features (20 to 40 kms wide) and form from the most
violent and infrequent eruptions (10,000 yr frequency).
FLOOD BASALT
Very high volume eruptions of fluid (low viscosity) lava that floods large areas.
Repeated effusions from fissures produce layers of basaltic lavas to form lava plateaus.
Fed from mantle plumes.
STRATOVOLCANO OR COMPOSTITE VOLCANO
Intermediate in size. Variable slope angles.
Volcanoes of the “Ring of Fire” (i.e. subduction zones ) are composites. Most commonly
made of andesitic lava.
These volcanoes reflect alternating compositions of magma and the highly variable deposits that result.
Deposits can alternate between lava flows and tephra deposits.
LAHAR
volcanic debris flows or mudflows (slurry of water and mud) resulting from rapid
melting of snow or glaciers near the summit.
LITHIFICATION
COMPACTION & CEMENTATION
STRATIFICATION
the layering that occurs in most sedimentary rocks and in those igneous rocks formed at the Earth’s surface, as from lava flows and volcanic deposits
RIPPLE MARKS
– Structures formed by wind or water
– Sediments accumulate downslope (lee side)
– Symmetrical ripples
* Bidirectional current
– Asymmetrical ripples
* Unidirectional current
TILTED DEPOSITS
May have once been horizontal but then deformed or uplifted.
CROSS-BEDDING
Sediments deposited on an angle.
Tends to happen in places with flowing water or blowing wind in one direction.
SALTATION
Sand particles jumping along the surface - moving higher and higher upon the dune until it reaches maximum steepness.
GRADED BED
Sediment consisting of mixed grain-sizes is sorted as
coarser grains settle more rapidly than finer ones
Grading upward from coarser to finer
(“fining-upward”)
AMBER PRESERVATION
Fossilized tree resin.
To keep soft tissues preserved, they must be kept away from oxygen.
COPROLITE
Fossilized feces.
BIO MARKER
Organism not preserved
Chemical residue of decay
TRACE FOSSILS
Tracks / trails/burrows
Provide behavioral
information about extinct
animals
CARBONIZATION
Processes of concentration of
residue carbon on the surface
of impression.
HYDROCARBONS (3):
- PETROLEUM
- NATURAL GAS
- COAL
PETROLEUM:
Petroleum (“rock oil”) is a naturally occurring,
complex mixture of hydrocarbons and includes:
– Crude oil (liquid)
– Bitumen (solid or very viscous liquid)
A fossil fuel formed from decomposition of organic chemicals (e.g. fatty molecules called lipids) derived mostly from plankton (marine algae and microorganisms) that are buried in sedimentary rock and subjected to heat and pressure.
NATURAL GAS
Natural gas is a naturally occurring, mixture of
hydrocarbon gases consisting mostly of methane
COAL
Sedimentary rock formed from the decomposition
of plant life and composed of organic grains.
MOST OIL OR GAS DERIVES FROM A…
“SOURCE ROCK” rich in organic matter, then migrates to a porous sedimentary rock with a natural trap, which forms a petroleum reservoir.
CONVENTIONAL OIL
Crude oil that flows naturally and can
be pumped to surface without being
heated or diluted.
Natural gas layers provide pressure on
the oil, causing it to flow when a well
is initially drilled.
UNCONVENTIONAL OIL
Crude oil that does not flow naturally
or cannot be pumped to surface
without heating or dilution.
Includes bitumen and heavy oil that is
thick and viscous.
Unconventional natural gas found in
tight shale (shale gas) and coal beds
ENHANCED OIL RECOVERY (METHODS)
Techniques used to lower the viscosity of crude oil so that more can be extracted from an existing oil field:
- gas injection (CO2)
- thermal injection
- steam flooding
GEOLOGICAL CO2 SEQUESTRATION
CO2 injected into a reservoir can rejuvenate depleted
reservoirs while storing (permanently) the CO2.
BITUMEN
Bitumen is a heavy oil that is a solid at 10C and
viscous like molasses at room temperature
Challenge to extract bitumen and to separate it
from the sand and water
OPEN-PIT MINING
Open pit mining used for deposits
within 70 m of the surface
– Tailings ponds allow solids to settle
and for water on top to be recycled
– Tailings ponds are of particular
environmental concern
STEAM-ASSISTED GRAVITY DRAINAGE (SAGD)
Step 1: Two horizontal wells are drilled – a
steam injection well over a recovery well
Step 2: Steam injected into the top well
lowers the viscosity of the oil and allows
it to drain downward to the recovery well
Step 3: oil then pumped to surface
Used to extract heavy oil in
Saskatchewan and Alberta
Also used in the Alberta oil sands
Water and energy intensive
CYCLICAL STEAM STIMULATION (CSS)
“Huff and Puff” method
Individual well undergoes three
separate phases
Stage 1 is a steam injection phase
Stage 2 is a soak phase that allows
enough time for the oil to lower in
viscosity
Stage 3 is the production stage when
the heated oil is pumped to surface
POROSITY
Is the volume of pore spaces in a given volume of rock, sediment or soil material.
Expressed in %.
PERMEABILITY
A measure of the rate at which soil or rock transmits a fluid such as water through its pores or cracks.
HYDRAULIC FRACKING
Technique used to fracture low permeability reservoirs
Fluid (water, carbon dioxide, nitrogen, or propane) injected down the well until pressure exceeds the rock strength
Fracking fluid has silica sand or ceramic beads (“proppant”) that keep the fractures open
Segments along the borehole can be fractured one at a time in a process known as multi-stage fracking
ENVIRONMENTAL CONCERNS WITH HYDRAULIC FRACKING
Air pollution from methane release
Requires a lot of water (recycled)
Chemicals in the fluids can leak into other formations
Pressurizing of a reservoir can induce seismicity
NUEE ARDENTE (GLOWING CLOUD)
Gas cloud of great heat, tremendous turbulence, and great force associated with these flows.
VOLCANIC HAZARDS
- LAVA FLOWS
- POISONOUS GASSES
- ASH
- PYROCLASTIC FLOW
- NUEE ARDENTE
- LAHAR
- TSUNAMI
GASSES RELEASED BY VOLCANIC ERUPTIONS:
– Water vapor (H2O)
– Carbon dioxide (CO2)
– Sulfur dioxide (SO2)
– Hydrogen sulfide (H2S)
– Hydrogen chloride (HCl)
TWO TYPES OF ISOTOPES:
- RADIOACTIVE
- STABLE (NON-RADIOACTIVE)
RADIOACTIVE ISOTOPE
Nuclei that decay at a constant rate to form other isotopes (daughter isotopes);
by measuring the amount of decay such isotopes have undergone while present in the rocks, geologists can date those rocks;
TYPES OF FRACTURES
- Conchoidal
- Parallel
- Irregular
- Splintery
CRYSTAL LATICE
The 3-D molecular structure of a mineral;
its configuration reflects relative sizes and
numbers of ions that make up the mineral;
CHARACTERISTICS OF A MINERAL
- naturally occurring
- inorganic
- solid
- characteristic crystalline structure
- definite chemical composition
CARRYING CAPACITY
Maximum population of a species that can
be supported by an ecosystem without
environmental degradation.
ATMOSPHERE
the gaseous envelope that encircles,
shields & insulates the earth.
HYDROSPHERE
Includes all water on the earth,
including oceans, lakes, rivers, ice,
atmospheric & soil water.
LITHOSPHERE
Solid portion of the Earth from the
interior to the crust, composed of rock,
unconsolidated materials, minerals, some
include soils.
BIOSPHERE
All living and dead organic materials,
plants, animals, and soils.
EXTRATERRESTRIAL
includes energy from the sun,
meteors, space dust, long-wave radiation
from earth to space.
TOPOGRAPHIC MAP
a two-dimensional representation of the shape and elevation of the land surface by means of contour lines.
CONTOUR LINE
a line on a map connecting points of equal elevation.
VECTOR DATA
Points, lines, polygons
- Useful for representing discrete features
- Land parcels, pipelines, buildings
RASTER DATA
Regular grid of cells
- Useful for representing continuous features
- Air-photos, satellite images, DEMs
FOLIATED
Directed pressure causes parallel alignment of mineral, textural, and structural features of a
metamorphic rock that can overprint the original texture.
NON-FOLIATED
Non-foliated rocks occur when the pressure is low or NOT a factor (contact metamorphism) or
the composition of the rock does NOT include platy minerals such as mica.
CONTACT METAMORPHISM
Igneous intrusion “bakes” surrounding rocks
REGIONAL METAMORPHISM
Temperatures and directed pressure
BURIAL METAMORPHISM
Temperatures without directed pressure
HYDROTHERMAL METAMORPHISM
Results from percolation of hot watery fluids
CATACLASTIC METAMORPHISM
Directed pressure (shear) grinds rock at low temperature along faults/shear zones
INDEX MINERALS
Minerals which only form at the temperatures and pressures associated with the process of metamorphism (a more stable form under conditions of high temp and pressure).
DIFFERENCE BETWEEN SCHIST AND GNEISS
SCHIST is characterized by coarse grained foliation and/or lineation, tendency to split along planes, with Mica crystals large enough to be easily identified with the unaided eye.
GNEISS is a medium to coarse-grained, irregularly banded rock (lighter and darker) with little tendency to split.
DYNAMIC METAMORPHISM
Metamorphism from high-pressure, low -temperature, shear zones
Restricted to narrow shear zones (fault zone).
CATACLASTIC
Rock formed by fracturing and mechanical grinding along a fault.
MYLONITES
Formed by ductile deformation in fault zones. They are formed by dislocation/diffusion creep (plastic) rather than mechanical abrasion (brittle).
“PLASTIC”
A permanent deformation or change in shape of a solid body without fracture under the action of a sustained force.
“BRITTLE”
Rocks fail as rigid solids. The rocks will break, rather than bend, under these conditions to produce fractures.
Brittle deformation occurs along discrete planes in the rock instead of involving the rock body as a whole.
FORCE
“Any influence that causes a free
body to undergo an acceleration.” (push or pull)
Recall Newton’s Second Law: F=ma
SHEAR
The plates slide past one another
STRESS
Force applied per area.
– Compressive
– Tensional
– Shear
THREE TYPES OF STRESS
- Compressive
- Tensional
- Shear
STRAIN
Deformation of a material as a result of
applied stress
(elastic, ductile, brittle fracture)
TYPES OF STRAIN
- Elastic
- Ductile
- Brittle
- Fracture
ANTICLINES
Anticlines are the upfolded parts of the rock layers.
OVERTURNED FOLDS
Overturned folds have an inclined axial plane and both limbs dip in the same direction.
RECUMBENT FOLDS
Recumbent folds have a horizontal axial plane
SYNCLINES
Synclines are the downfolded parts of the rock layers.
DOMES (FOLDS)
Anticlinal upwarped strata with oldest rocks in the centre
BASINS (FOLDS)
Synclinal depression with youngest
rocks in the centre
TWO TYPES OF FRACTURES
- JOINTS: are fractures along which there
has been no movement. - FAULTS: are fractures along which there
has been movement.
HANGING WALL / FOOTWALL
HANGING WALL is the wall directly above the fault line.
FOOTWALL is the wall directly below the fault line.
THREE TYPES OF FAULTS
- Normal: tensional, hanging wall drops
- Reverse (thrust): compressional, hanging wall rises
- Strike-slip (transform): shear, lateral displacement
EARTHQUAKE
The vibration generated by the sudden release of energy associated with rapid movement of rock along a fault.
FAULT PLANE
The fracture surface between one block and another along which movement occurs.
EPICENTER
A location on the earth’s surface directly above the focus.
FOCUS
The ‘origin’ of the earthquake, that point within the earth’s crust where movement first occurred.
SEISMIC WAVES
Waves of energy that travel like shock waves from the focus to the surrounding area.
TWO TYPES OF SEISMIC WAVES
- Body waves: travel through the interior
* P-waves: primary, “push-pull” waves
* S-waves: secondary, “shake” waves - Surface waves: travel along the surface. Referred
to as L-waves or long waves due to longer period.
* Love-waves
* Rayleigh waves
P-WAVES (PRIMARY)
- Fastest waves (first to arrive)
- “push-pull” waves
- Compression and expansion
- Change in volume not shape
- Travel through all materials
S-WAVES
- Slower than P-waves (Second to arrive)
- “shake” waves
- Side-to-side
- Change in shape not volume
- Fluids do not transmit S-waves
Seismic waves are detected by an instrument
called…
A seismometer and recorded as a paper
trace known as a seismogram
SEISMOGRAM
- P-waves arrive first followed by the arrival of S-waves
- Note time interval between P- and S- waves
- Surfaces waves arrive last
Using the P- and S-wave interval to determine the distance to the epicenter from
at least…
THREE stations allows us to triangulate the location of the earthquake.
TWO APPROACHES FOR ASSESSING THE “SIZE” OF AN EARTHQUAKE
- INTESNITY
- MAGNITUDE
MOMENT MAGNITUDE
Scale matches the antiquated Richter scale for small magnitude earthquakes and extends the scale to better represent larger earthquakes.
1) THE MOUNT OF GROUND SHAKING 10X
2) EQUATES TO THE EMOUNT OF ENERGY RELEASED 32X
EARTHQUAKE HAZARDS
- Ground Shaking
- Fault Displacement
- Landslides
- Liquefaction
- Tsunami
CRUST
- Oceanic crust = thinner and denser
- Continental crust = thicker, less dense
MANTLE
– Fe and Mg silicates
– Plastic behavior
CORE
– outer core = iron-rich liquid
– inner core = solid iron.
LITHOSPHERE
– Crust plus uppermost mantle (differ in density but firmly attached)
– Rigid and brittle behavior
ASTHENOSPHERE
– Below the lithosphere (still belongs to upper part of the mantle)
– Low-velocity seismic waves indicate partially molten rock
– Plastic behavior
OCEANIC CRUST
Oceanic crust is about 5-8 km thick,
– Composed primarily of basalts and gabbros.
– Average density 3 g/cm3
– Rocks approx 180 million yrs old or less.
CONTINENTAL CRUST
Continental crust is about 20-70 km thick (40-45 km thick average),
– Composed of a mixture of rock types. Granitic.
– Less dense 2.7 g/cm3
– Rocks are older (4 billion yrs old - Acasta gneiss in the NWT.)
