GEOG 1401 Exam 3

Relation between chemical and physical weathering?

Physical weathering increases the rate of chemical weathering.

Hydrologic cycle

Amount of water on Earth is relatively constant.

Interception

Precipitation gets intercepted on plants which then evaporate or fall to the ground.

Infiltration

Water seeps below surface.

Runoff

Water flows downhill over surface.

Evaporation

Depends on relative humidity, wind, and temperature.

Relative humidity

Amount of water vapor in air relative to the maximum amount that air can hold.

Transpiration

Water from soil taken up by plants and evaporated from leaf surface.

Porosity

Amount of open space between soil particles.

Permeability

Ease of water moving through soil.

Factors affecting infiltration

Porosity, permeability, vegetation, animals.

Capillary water

Temporarily attaches, available for plants to use. Attraction decreases as more water attaches.

Gravity water

Not attached, gravity pulls it down.

Field capacity

How much capillary water can soil hold.

Wilting point

Most capillary water is gone, plants can’t get enough to stay healthy.

Groundwater

Where all pore spaces are filled with water– no air.

Aquifer

Subsurface material that holds groundwater, has enough porosity/permeability to accumulate.

Aquiclude

Subsurface material with low permeability, prevents groundwater from moving through.

Water table

Upper limit of groundwater.

Artesian well

Water table’s higher than top of the well, water flows freely.

Cone of depression

Using groundwater often lowers water table around the well.

Throughflow

Water infiltrates soil, but some moves parallel to slope, emerging downslope to becomes overland flow.

Baseflow

Keeps stream flowing if water table’s above stream’s bed.

Effluent streams

Water table’s higher than bed. Perennial = flows all year.

Influent streams

Water table’s lower than bed. Ephemeral = only flows with overland flow.

Intermittent stream

Flows part of year because seasonally effluent.

Hydrograph

Graph of stream flow over time.

Subsidence

Groundwater helps hold up surface in some places.

Salt water intrusion

Along some coasts, salty groundwater takes fresh groundwater’s place.

Geomorphology

Study of landforms and the processes that shape them.

Powell

Introduced the idea of base level.

Base level

Streams can only erode to a certain level– sea level is the ultimate base level.

Gilbert

“Landforms tend to equilibrium,” Theory of Graded River.

Graded river theory

Stream adjusts to slope to transport available sediment with no extra energy.

Davis

Dominated geomorphology for first half of 1900s.

Cycle of erosion

Flat surface at base level (peneplain) undergoes rapid uplift, now above sea level.

Kinetic energy

Based on mass and speed.

Potential energy

Not used now, but might be in the future.

Q = A*V

Discharge(Q) defines as cross sectional area(A) * average velocity(V).

Laminar flow

Slow water may move in a straight line.

Turbulent flow

More chaotic flow, typical in streams.

Factors affecting stream velocity

Channel slope, discharge, depth of flow, roughness of channel.

Positive relationship

Variables are positively related if they change in the same direction.

Negative relationship

Variables are negatively related if they change in the opposite direction.

Shear stress

Friction transferring some energy from water to bed.

Stream load

Sediment carried by stream.

Competence

The size of the largest particle a stream can carry at a given discharge.

Capacity

Amount of sediment a stream can carry at a given discharge.

Types of erosion

Hydraulic action: Flowing water picks up loose material.

Bank caving: Sides of a channel falling into a flow.

Abrasion: Colliding particles break down and become more rounded.

Corrosion: Chemical weathering in streams makes rocks dissolve.

Erosional landforms

Waterfalls, canyons, etc.

Depositional landforms

Deltas, alluvial fans, etc.

Floodplain

Flat surface next to a channel that frequently gets flooded, each flood deposits more sediment.

Meandering channels

Bendy channels. Outside curves = erosion, inside curves = deposition.

Braided channels

Found where discharge varies and high sediment loads.

Recurrence interval

Time between floods of a given size.

Drainage network

Series of connected streams.

External drainage basin

Flow exits basin at one point.

Interior drainage basin

No outlet, so flow accumulates in a low spot (playa).

Longitudinal profiles

Slope of channel tends to change in downstream direction.

Air and water flow

Both are fluids that flow in similar ways.

Suspension

Sediment stays above surface.

Saltation

Sediment bounces.

Creep

Sediment rolls and slides on surface.

Sorting

Different sizes of sediment travel differently, so mixed sizes get divided by size after deposition.

Factors affecting wind erosion

Wind speed, vegetation, soil conditions.

Bagnold

Taught more about Aeolian geomorphology than anyone else.

Ripples

Small ridges.

Dunes

Hills of windblown sand.

Sand seas

Regional accumulations of windblown sand.

Parts of a dune

Backslope (10-15º), crest, slipface (34º).

Angle of repose

Loose materials can be stacked to a certain angle before falling due to instability.

Transverse dunes

Crest is perpendicular to one main wind direction.

Linear dunes

Two main wind directions from similar directions. Crest is parallel to average direction.

Reversing dunes

Wind from opposite directions.

Star dunes

Complex wind pattern forms a peak with radiating arms.

Parabolic dunes

Stabilized but part becomes unstable. Forms a U shape with horns pointing upwind.

Blowout

Depression formed by erosion following vegetation removal.

Loess

Thick deposit of windblown dust.

Evolution

Changes that take place in a species over time.

Natural selection

Some individuals are better adapted to environment = more likely to pass genes to next generation. Driving force of evolution.

Microevolution

Change over time within a species.

Macroevolution

New species evolves.

Darwin & Wallace

Pioneers of evolution.

Species range

Area where a species is found.

Dispersal

Ability to move to new areas.

Adaptation

Species evolve by adapting to their environment.

Abiotic factors

Adapting to non-living things (Temp, water, etc…)

Biotic factors

Adapting to other living things.

Limiting factor

Determines range.

Ecology

Study of organisms and how they interact with other organisms/physical environment.

Ecosystem

Organisms/physical environment of a particular environment.

Energy flow

Secondary consumers → Primary consumers → Producers

Biogeochemical cycles

Carbon cycle: Air to plants, Plants to air, decomposers, and animals, Animals to air and decomposers, Decomposers to air.

Nitrogen cycle: Plants get N from soil, animals eats plants, N is released to atmosphere in decomposition.

Biodiversity

Number of sepcies in an area.

Orders of relief

Different scales of the shape of the land.

2nd order features of oceans

Shelf, slope, rise, abyssal plain, mid-ocean ridge.

2nd order features of continents

Mountain chains, mountain roots, exposed shields, covered shields.

Wegener

Suggested continents were once fused as Pangea.

Paleomagnetism

Shift in magnetic poles.

Sea floor spreading

New material created at mid-ocean ridges.