Test 3 Flashcards
Scarification
Human induced mass movements.
Geologic time scale
- Relative dating
2. Absolute dating
Relative dating
Determining the order of what occurred first. Uses the “Principle of superposition” as well as fossils.
Principle of superposition
Younger rocks are superimposed on top of older rocks.
Absolute dating
Determining the specific number of years before the present. Uses “radiometric dating.”
Radiometric dating
Measuring time by the know decay rate of certain elemental isotopes.
Catastrophism
Emphasizes the concept that rapid, large-scale catastrophic events have shaped the planet.
Uniformitarianism
Assumes the same physical processes that are occurring today have operated throughout geologic time.
Punctuated Equilibrium
Episodic catastrophic interruptions in the otherwise generally uniform processes conceptualized by Stephan Jay Gould.
How old is Earth?
4.6 billion years old.
How did Earth’s structure form?
Gravity brought heavy elements to center, formed layers.
What processes make Earth emanate heat from the center?
Conduction and convection.
Characteristics of the core
- 1/3 mass, 1/6 volume.
- Solid iron inner core, molten less dense outer core.
- Generates magnetic field.
Characteristics of the mantle
- 80% of Earth’s volume.
- Increasing temperature with depth.
- Increasing stiffness with depth.
Characteristics of the asthenosphere
- Plastic layer below lithosphere.
2. Movement in this layer produces tectonic activity.
Characteristics of the lithosphere
- Rigid outer layer of rock.
2. Includes continental and oceanic crust.
Continental Crust
Less dense (granitic) Silica, aluminum, potassium.
Oceanic Crust
More dense (basaltic) Silica, magnesium, iron.
Isostasy
Isostasy controls the regional elevations of continents and ocean floors in accordance with the densities of their underlying rocks.
Isostasy adjustment
Ocean basins have gotten larger since the end of the last glacial cycle because ice sheets that once covered North American and Europe have melted in the last 20,000 years.
What are the most abundant elements in the crust?
Oxygen and silicon.
Definition of rock
Rock is a chunk of Earth’s surface, usually lots of minerals together.
Mineral
Inorganic, natural compound with a specific chemical formula and possessing a crystalline structure.
4 Mineral Families
- Silicates
- Oxides
- Sulfides & Sulfates
- Carbonates
Silicates
Silicon and oxygen
Oxides
Oxygen and metallic elements
Sulfides & Sulfates
Sulfur and metallic elements
Carbonates
Carbon with oxygen and other elements
3 types of rocks
- Igneous- liquid rock that cools.
- Sedimentary- forms from pieces of other rocks or through a chemical process; evaporation.
- Metamorphic- changed though heat pressure and chemical fluids, heat up not hot enough to melt.
How to classify Igneous rocks
Igneous rocks are classified by color (light [felsic]/dark [mafic] and the size of crystals large [intrusive]/small [extrusive].
Lithification
The process in which sediments compact under pressure, expel connate fluids, and gradually become solid rock.
Plate tectonics
Plates shift and move over the Mantel.
Mid-ocean ridges
Underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.
3 plate boundaries
- Divergent
- Convergent
- Transform
Divergent boundary
Found in deep oceans. Two plates pulling apart from each other. Mid-ocean ridges.
Convergent boundary
Collision of two plates. The more dense oceanic plate goes under the less dense continental plate usually. Causes earthquakes and volcanoes. The Himalayas are a result of this.
Transformation boundary
Two plates slide by one another in opposite directions. The San Andreas Fault.
What is the correlation between earthquakes/volcanoes and plate boundaries?
Convergent boundaries cause them when the oceanic plate subducts the continental plate and starts to melt.
Hot spots
Volcanic regions thought to be fed by underlying mantle that is abnormally hot and therefore rises. Hawaii was formed this way.
Relief
Vertical elevation difference in the landscape.
Topography
The undulating form of the Earth’s surface, including its relief.
Origin of the Continental Crust
- Inactive remnants of tectonic activity.
- Folding and faulting from crustal movement.
- Volcanic features.
Craton
Older nucleus built on to form continents.
Continental Shields
Where craton appears at the surface.
Terranes
Pieces that become attached to plates.
3 types of Stresses
- Tension (stretching)
- Compression (shortening)
- Shear (twisting and tearing)
2 types of strain (how rocks respond to stress)
- Folding (bending)
2. Faulting (breaking)
Folding (bending)
Anticline and syncline. The landscape is all wavy and shit.
Faulting (breaking)
- Normal fault
- Reverse fault
- Strike-slip fault
Normal Fault
Pulling apart. Tensional stress.
______
______/–>
<–/
Reverse Fault
Pushing together. Compressional stress.
______
//
Strike-slip Fault
Sliding besides each other. Right lateral and left lateral. The one below is left-lateral because while standing on one side and facing the other, it shifted to the left.
Basin and range is an example of normal faulting due to tension as you live in the basin and range Provence of the US
Basin and range is an example of normal faulting due to tension as you live in the basin and range Provence of the US.
Faulted landscapes
Horst (upfaulted block) mountains surround Graben (downfaulted block) valleys.
Orogenesis
Mountain building episode (millions of years)
Types of Orogenies
-Ocean plate – continental plate collision
-Collision building Mts.
-Subduction of oceanic plate, leads to volcanism
-Ocean plate – ocean plate collision
-Slight-subduction of one oceanic plate leading to volcanic island arc.
-Continental plate – continental plate collision
-Collision building Mts.
-Some subduction
3 parts of earthquakes
- Focus
- Epicenter
- Waves of energy propagate from focus in all directions.
Focus
Spot along fault where quake originates.
Epicenter
Point on surface directly above the focus.
Difference between Mercalli, Richter and Moment Magnitude
The Richter Scale, measures an earthquakes magintude by numbers.
The Mercalli Scale, measures the intensity of an earthquake.
The Moment Magnitude Scale is used to measure an earthquakes size and how much energy was released from the seismic waves.
Types of Volcanic Activity
- Effusive Eruptions - pours out a more liquid type of lava more frequently (Shield type volcanoes).
- Explosive Eruptions - has a more viscous type of lava that leads fewer eruptions that are more violent (Composite type volcanoes).
Volcanos
Associated with plate boundaries and hot spots.
Shield vs. composite volcanoes
Shield aren’t as tall and have very shallow sloping sides. They have thin, runnier lava with low silica content. They form on constructive plate boundaries where two plates are pulling apart.
Composite are tall and more narrow with large craters at the top. They have thick lava with high silica content. They form on destructive plate boundaries over subduction zones.
Geomorphology
Science of landforms: origin, form, and spatial distribution.
Denudation
Any process that wears down or rearranges landforms.
- Weathering
- Mass Movement
- Erosion
- Transportation
- Deposition
Differential weathering
Different rates of weathering based on the physical and chemical characteristics of the feature.
Landform processes are the result of a dynamic equilibrium.
Landform processes are the result of a dynamic equilibrium.
Weathering
The breakup of rock features. Physical weathering
and Chemical weathering.
Physical weathering
Breaking and disintegration of rock without any chemical alterations.
- Frost Action – expansion of water splits rocks
- Crystallization – evaporation of water leaves behind mineral crystals that grow and split rocks
- Hydration – combining of water with minerals expands and breaks up rocks into grains
- Pressure-release jointing – jointing of large rock masses into thin layers as a result of releasing pressure.
Chemical weathering
The decomposition of minerals that make up rocks by chemical processes. Reaction between air & water and rocks.
- Hydrolysis – when minerals chemically combine with water, resulting in their breakdown.
- Oxidation – combination of oxygen with metallic elements.
- Carbonation & Solution
- Carbonation – creation of carbonic acid H2CO3 which chemically dissolves minerals.
- Solution – when the mineral is dissolved and suspended in H2O.
Karst
Limestone areas chemically weathered by moisture. Caves and Caverns and Sinkholes.
Formation of Karst
- Limestone dominated by calcium carbonate
- Existing jointing
- Aerated portions underground
- Groundwater and vegetation
Caves and Caverns
Subterranean open areas formed as groundwater removes the limestone.
Sinkholes
Circular depressions on the Earth’s surface that appear as gaps or weakened rock layers collapse.
Mass Movement
Any unit movement of a body of material under gravity.
Angle of repose
The steepness angle that a pile of material will form when it has stabilized.
Classes of Mass Movements
- Fall (rockfall)
- Slide (landslide, slump)
- Flow (earthflow/mudflow)
- Creep (soil creep)
Fluvial
River processes
Functions of a river
- Drainage
- Erosion – the process of dislodging, dissolving or removal of material
- Transportation – the movement of material
- Deposition – when materials are laid down by water (alluvium)
Stream
Any stream is a mixture of water and solids.
Base level (Form of a river)
- Ultimate base level - the ocean.
2. Local base level - a temporary base level limiting the erosion of local streams.
Produced landforms (Form of a river)
- Erosive action of flowing water.
2. Deposition of alluvial material
Drainage basin (Form of a river)
An area of land where runoff collects and moves through the same area.
Watershed (Form of a river)
A word used specifically to refer to the catchment area of a drainage basin.
Internal drainage (Form of a river)
One that never reaches the ocean.
7 drainage patterns
- Dendritic (tree-like pattern, efficient energy use).
- Trellis (parallel larger flows that are interconnected, folded topography).
- Radial (flow off of a central peak or dome).
- Parallel (parallel flow, associated with steep slopes).
- Rectangular (stream courses at right angles, jointing).
- Annular (circular pattern occurring on domes, where water follows layers).
- Deranged (no clear pattern or geometry, disruptions).
Discharge (Q) – a stream’s rate of flow
Q = w * d * v
w - channel width
d – channel depth
v – velocity
Competency
The ability to move particles of a given size.
Capacity
Amount of material a stream can move.
How material is transported
- Solution – dissolved load derived from chemical weathering of minerals.
- Suspended load – fine grained material held aloft in water.
- Bed load – coarse material dragged along the streambed.
Aggradation
Deposition of sediments. Slower velocity (decreasing capacity and competency).
Degradation
Erosion. The removal of sediments and rock. Faster velocity (increasing capacity and competency).
Types of stream channels
- Straight
- Braided – several interconnecting channels.
- Meandering – a single winding channel.
- Undercut bank – degradation feature on outside. of bend.
- Point bar – aggradation feature on inside of bend.
Wind (eolian), agent of geomorphic change
Wind (eolian), agent of geomorphic change.
Wind
It erodes, transports and deposits sediments. It does so less significantly than water.
Grain size determines wind erosion; 3 types
- Intermediate – move easily by bouncing.
- Large particles – resist movement due to their weight.
- Small particles – resist movement due to their mutual cohesiveness.
2 principal types of wind erosion
- Deflation – lifting and removal of individual loose particles. Desert pavement and Blowout depression.
- Abrasion – grinding of rock surfaces with a “sandblasting” action. Ventifacts.
Desert pavement (deflation)
Area dominated by pebbles and rocks due to the removal of fine sediments by wind and water. Prevents further deflation.
Blowout depression (deflation)
Basins created by the removal of material (1-100+ meters).
Ventifacts (abrasion)
Rocks shaped by the abrasive force of wind-blown particles.
Eolian transportation
- Suspension
- Saltation
- Surface creep – sliding or rolling of particles across the ground due to the impact of saltation
Ripples (Eolian deposition)
Small features of linear crests and troughs formed transversely (at right angles) to wind.
Dune (Eolian deposition)
Transient, wind sculpted ridges or hills composed of sand.
Erg (Eolian deposition)
A sand sea or an area predominated by dunes.
Loess
Thick deposits of fine-grained clays and silts accumulated in various parts of the world by
eolian processes. It is fertile soil; thick, well drained, and capable of retaining their moisture.
Three climate controls of deserts
- Subtropical highs (15-35oN&S)
- Rain shadows of mountains
- Continentality
Common characteristics of deserts
- High sensible heat
- High ground heating
- High POTET, leading to large DEFIC
- Intermittent streams
Desert fluvial landforms
- Flash flood
- Wash (arroyo)
- Playa
- Exotic streams
- Alluvial fan
- Bajada
Flash flood
Sudden torrent of water that fills a channel.
Wash (arroyo)
A dry stream bed.
Playa
A temporary lake, existing only during wet periods.
Exotic streams
A stream whose headwaters originate in a different type of climate.
Alluvial fan
Fan-like deposit of sediments at the mouth of a canyon stream.
Bajada
Broad slope composed of several alluvial fans.
Cross-bedding
It’s like layered and shit. Like Red Rock.
Desertification
A process by witch we degrade arid or dry landscape, pretty much destroying. Overgrazing, Over irrigation causing a buildup of salts, Increased erosion due to agriculture, Climate change.
Glacier
Large flowing rivers of ice. 18 meters thick is when it starts to rechrystalize and start flowing under it’s own weight.
Alpine Glaciers
Valley, Cirque, Piedmont, and Tidal
Continental Glacier
Much larger than alpine glaciers. Form over landmasses and the oceans, covering all but the highest elevations and spreading out in all directions.
Firn
A compact, granular stage in glacial ice formation
Only about 25% air (regular ice can be 50% or more).
Ablation processes
Melting, calving (chunks falling off the side), wind, and sublimation (turning directly into gas).
Glacial Mass Balance
Positive mass balance = advancing glacier
Negative mass balance = retreating glacier (doesn’t actually literally retreat)
Parts of a glacier
- zone of accumulation - where the glacier starts
- zone of ablation - where the glacier ends and melts and evaporates and shit.
- till - shit dumped off
- moraine - a linear pile of till
- terminal moraine - pile at the bottom
- lateral moraine - pile on the sides
- medial moraine - shit that accumulates in the middle where the glaciers meet.
Glacial movement
Fastest rate of flow is at the top and in the middle, because of friction.
Erosional features
- Glacial polish
- crevass
Alpine Glacial Landscape
- Narett- sharp knifelike ridge between 2 glaciers.
- Horn- where 3 glaciers come together.
- Cirque- basins
Postglacial landscape
- Catnanoster lakes- chain lakes
- Tarn- single lake
- U-shaped valleys
- Hanging waterfalls
- Glacial erratics
- Erratics are huge boulders that glaciers move.
Periglacial features
Permafrost Active layer Talik Ice wedge Pingo
Kettle
Where ice forms a depression.
Kane
Where a rounded hill forms.
Drumlin
A tear shaped hill. Prominent side is where is is coming from. They often from in swarms. Made of till.
Periglacial Landscapes
- Permafrost - soil or rock remain below 0°C for 2+ years.
- Active layer - layer of soil that freezes and melts each year.
- Talik - unfrozen ground that occurs in patches throughout permafrost.
- Ice wedge - a wedge of ice that forms due to freeze-thaw expansion.
5. Pingo - a heaved-up circular ice-cored mound
