Topographic maps, earthquakes, groundwater, stream processes, and glacier terms
What are Earthquakes?
The shaking or trembling caused by the sudden release of energy in the Earth's rock. Usually associated with faulting or breaking of rocks.
Continuing adjustment of position results in aftershocks.
What is Elastic Rebound Theory?
Explains how energy is stored in rocks:
Rocks bend until the strength of the rock is exceeded
Rupture occurs and the rocks quickly rebound to an undeformed shape
Energy is released in waves that radiate outward from the fault
The point within Earth where faulting begins; also called hypocenter
The point directly above the focus on the surface
Where do Earthquakes occur and how often?
80% of all earthquakes occur in the circum-Pacific belt
most of these result from convergent margin activity
more than 150,000 quakes strong enough to be felt are recorded each year
Economic and Social Impacts of Earthquakes (4)
What are Seismic Waves?
Response of material to the arrival of energy fronts released by rupture
What are the two Body waves?
P and S waves
Fastest waves; travel through solids, liquids and gases; compressional waves
material movement is in the same direction as wave movement; P-waves
S waves (3)
slower than P waves; travel though solids only; shear waves
move material perpendicular to wave movement; S-waves
What are the two surface waves?
R and L waves
travel just below or along the ground's surface; slower than body waves, rolling and side-to-side movement; especially damaging to buildings
Reaction of P-wave to dilation and compression detected at seismic stations
pulling rocks apart (first movement down on a seismograph)
squeezing rocks together (first movement up on a seismograph)
How is an Earthquake's epicenter located?
By seismic wave behavior:
P waves arrive first, then S waves, then L and R
Average speed for all these waves is known
After an earthquake, the difference in arrival time at a seismograph station can be used to calculate the distance from the seismograph to the epicenter
showing the average travel times for P and S waves. The farther away a seismograph is from the focus of an earthquake, the longer the interval between the arrivals of the P and S waves
What is need to locate the epicenter?
Three seismograph stations
How are the size and strength of an earthquake measured?
by intensity and magnitude
subjective measure of the kind of damage done and people's reaction to it
What are the destructive effects of earthquakes?
amplitude, duration, and damage increases in poorly consolidated rocks
Can Earthquakes be predicted?
by Earthquake precursors
changes in elevation or tilting of land surface, fluctuations in groundwater levels, magnetic field, electrical resistance of the ground; seismic dilatancy model; seismic gaps
What is a glacier?
the existence of year-round ice in the landscape
What are the two broad types of glaciers?
Continental and alpine
How do glaciers form?
glaciers form whenever snowfall exceeds snowmelt year after year. The snow accumulates incrementally, pressure increases, and it is changed into never and then ice by this pressure.
a semicirculr or amphitheater-shaped bedrock feature created as glaciers scour back into the mountain. This is where the snow and ice forming the glacier first accumulates; it is the "headwaters" of a glacier.
Steep-sided, sharp-edged, bedrock ridge formed by two glaciers eroding away on opposite sides of the ridge.
What are the two ice sheets that exist today?
Greenland and Antarctica
1.a graphical representation of the three dimensional shape of the earth's surface
2. a reduced, simplified, categorized/classified, symbolized and annotated representation of the earth's surface which has been projected on a horizontal plane
a family of lines drawn on the globe parallel to the equator
circles drawn on the globe that pass through the two poles
the process of constructing a map, the transferring of the meridians and parallel to a flat sheet of paper
a means of showing the relationship between the size of an object or feature indicated on a map and the actual size of the object on the ground.
What are the three scale types?
Fractional, graphical, verbal
a contour line is an imaginary line on the surface of the earth connecting points of equal elevation
contour interval (C.I.)
the difference in elevation between any two adjacent contour lines
a diagram that shows the change in elevation of the land surface along any given line
the water which is contained within the saturated zone beneath the Earth's surface
a process by which water is transported from one part of the Earth to another.
Zone of Aeration
comprised of water and air filled spaces
a process by which water is returned to the atmosphere by the transpiration of living plants.
Zone of Saturation
every pore space is completely saturated/filled with water.
upper surface of the saturated zone which divides the saturated zone from the unsaturated zone.
an underground unit of soil/rock/sediment that can yield a significant quantity of groundwater
the capacity of rock/unconsolidated material to transmit a liquid
measure of the volume of pore space per volume of rock/sediment
aquifers which are bound above and below by a confining layer.
layer of sediment/rock which has a lower permeability than the aquifer that is confines
does not have a confining later above it
Water table aquifers
when a well is excavated the level to which the water rises within the well
Flowing well or spring
when the potentiometric surface is above the surface of the ground
pollution which has a single identifiable source of pollution
pollution that may come from a variety of sources and has no apparent source
the times is takes a given particle of water to traverse a given distance in a stream
all water molecules travel along similar parallel paths
individual water particles take irregular paths
the amount of water flowing in a stream, which is the volume of water passing any point in a given time interval
Area x Average Velocity
the rock particles and dissolved ions carried by the stream
particles that are carried along with the water in the main part of the streams
coarser and denser particles that remain on the bed of the stream most of the time but move by a process of saltation (jumping) by a result of collisions between particles, and turbulent eddies
ions that have been introduced into the water by chemical weathering of rocks. this load is invisible because the ions are dissolved in the water.
characterized by water flowing in a channel of some sort
relates to stream
the area of land that contributes water to stream; drainage basin
the upstream part of a stream near its origin
the downstream end of a stream where it empties into another stream or body of water
a smaller stream that joins a larger, mainstem stream
a larger stream that is joined by smaller tributaries
the steepness of the slope of the stream bed, generally steeper near headwaters and becoming gentler towards the mouth.
pools are deep and smooth. steps are formed by water running over a shallow rocky area (a bar) and down into a pool. Due to high gradient channels with rocky sediments.
riffles are shallow and turbulent of water flows over a bar
the bottom of the stream channel
the sides of the stream channel
gently sloping sediment deposited on the inside of the bend.
the deepest part of the stream channel
the movement of sediment from its source to another location
Bank full width
the width of a stream channel when the water just fills the channel but does not overlap the banks
The level are near a stream channel constructed by stream overflow during flood events.
abandoned floodplains and usually have a higher elevation that the present floodplains
Dendritic drainage pattern
resembles the branching of a tree, many tributaries flowing into the mainstream of the stream
channels that form right angle bends
channel flow outwards from the center, resembles the spokes of a wheel
channels flow to a center point
annular (radical) drainage
streams form concentric rings connected by short radical channels
the mainstream is intersected by angular tributaries, resembles a vine
Flood hazards: normal stage
when the water level of a river is below the river's banks
Flood hazards: bankfull stage
when the water level is even with the banks
Flood hazards: flood stage
when the water level exceeds the banks
difference in elevation
rectangular sections of Earth's surface bound by lines of latitude and longtiude
difference between MN and GN, is exact only for the year listed on the map
how maps are updated through aerial photographs to discover changed in the landscape
topographic maps are made from overlapping pairs of photos
lines marked with numbers
a permanent marker, labeled as an X symbol on the map
measure of the steepness of a slope
the difference in elevation between the highest and lowest point a topo map
stripes of longitude having a width of 6 degrees
rain that soaks into the ground
water in lakes and streams
flow continuously through the year
flow only during certain times of the year
where sediments are deposited
entire stream drainage system
lines boundaries that separate stream drainage system
the small valleys in a drainage basin occur at it's highest elevation
point of origin of stream
process of form v-shaped erosion
end of river valley
the slope of the water surface
a distinctive topography that indicates dissolution of underlying soluble rock
surface depression formed by the collapse of caves or other larger undergrounf void spaces
valley-like depressions formed by a linear series of sink holes or collapse of the roof of a linear cave
places where water flows naturally from the ground
streams that terminate abruptly by seeping into the ground
icicle-like masses of chemical limestone that hang from ceillings
water flows naturally from the top of the well
winter accumulation of snow and ice exceeds the summer ablation
the loss of snow and ice by melting and sublimation to gas
direct change from ice to water vapor, without melting
regions of permanent snow cover
Zone of Accumulation
as snow and ice collect they become compacted and highly recrystallized under their own weight
Zone of Ablation
ice melts or sublimes faster than new ice forms
the boundary between the zone of accumulation and ablation
the bottom end of the glacier
when a glacier melts, it appears to retreat up the valley from which it flowed
deposits of rocky gravel, sand, silt, and clay accumulate where there once was ice
drift that accumulates directly from the melting ice is unstratified
drift that is transported by the melt water becomes sorted by size
wind-transported glacial material
long glaciers that flow down stream valleys in the mountains
mergers of two or more valley glaciers at the foots of a mountain range
a vast, pancake-shaped ice mound that covers a large portion of a continent and flows independent of the topographic features beneath it
the upper end of the glacier is the large part that separates the flowing ice from the relatively immobile portion of the snowfield
the other cracks or open fissures that form when the velocity of ice flow is variable