This site is 100% ad supported. Please add an exception to adblock for this site.

Geology 311


undefined, object
copy deck
Angular Unconformity
an unconformity in which the older strata dip at an angle different from that of the younger beds
this is a type of unconformity where the strata above and below an irregular contacat are parallel. The contact represents a surface of erosion or of non-deposition.
an unconformity is which older metamorphic or intrusive igneous rocks are overlain by younger sedimentary strata
A stream that is established before a slow upligt occurs.
An anteceden stream continues its downward erosion as uplift continues.
The stream maintains its original pattern, as it erodes through the fold or ridge.
The antecedent stream is older than the geological structure through which it flows.
Results can be a deep gorge carved through hills or mountains.
A break in a rock mass along which appreciable movement has occurred.
Fault Scarps
Steep, linear bluffs produced by tectonic off-setting of the land surface along the trace of faults (escarpments)
Triangular Faults
When v-shaped valleys are cut into scarps, the remainder of the fault face on spurs between balleys assumes a triangulr shape known as a triangular faced
Sag Pond
an area between two parallel fault zones that has dropped, or sagged, down creating a depression that can fill with water
3d anticline, oldest in center
3d syncline, youngest in center
a type of fold where there is one axis of inclination like a stair step, produced by subsurface normal fault, causing stair step
homoclines are regions where the rocks dip uniformally over a wide area
upturned, u-shapped, involved compressional stress, dip symbols are pointing away from each other, oldest rocks ar found in the center of the structure
compressional stress, due to composition rocks are bowed u pward, dip symbols are pointing toward each other, youngest rock in center of features
Plug Dome
high in silica, lava ooze but on the ground surface like thick tooth paste and does not flow far from the vent, piling up steep sided plug domes, size of smalll cinder cone, associated with convergent plate boundary...
develop around small vents when molten lava is tossed into the ari by exploding gases in the magma, blobs of airborne laba fall arou nd the vent where they weld themselves to previously deposited material building up a small cone
Table Mountains
a flatttoped volcanic cones with steepsides composed of pillow lava, palagonite
(like obsidiean (, and vitreous pyroclastic rocks, yokelhauts,. form beneath glacier, basaltic mamgma, iceland
continental volcanic arc
volcanic island arc
continental + comntinental
collision mountains
driven by Earth's internal heat produced
-orogenic = mountain building, and deformation at plate boundaries
-epeirogenic = regional uplift or subsidence of the crust due to the principles of isotacy
drive by solar radiation and gravity
=ocean currents
-atmospheric circulation
stress v strengthq
FG + FP = stress
FN + FF = strength
Sheer Stress
strike-slip fault
Sheer strength
opposijng forces that act to resist downslope movement
Strombolian Type
typified by regular, sometimes rhythmic explosions of mild to modest intesntiy, basaltic lava froms a crust over the vent, crust is blown off by increasing pressure that throws a pasty incandescent lava and fragments (blems/boms) into the air
Vulcanian types
basaltic to andesitic lava (more silica more vicous)
-cinder cone to spatter cone
-vent plug is thicker requireing more pressure to remove it, blow it out
-powerful explosions result in scoria, pumice, ash, and bombs being ejected
Pelean Types
characterized by nuee ardents, and pyroclastic flows, glowing clouds of extremely hot gas and incandescent ash which rush down the slopes of volcanoes at velocities approaching 100mph
typically andesitic stata volcano?
seen in caribbean volcanoes
SuperImposed Stream
a river develops its pattern on rock laters, which are then removed by erosion, the river is now flowing over older rocks that habve veen uncovered, the existing stream pattern has been superimposed on the nearly uncovered landscape, these rivers are younger than the structures that they presently flow through
a structure that results from the emplace ment and crystallization of magma beneath the surface of the earth
Types of Plutons
dikes = tabular discordant
sill = tabular concordant
lacolith = mushroom, concordant
lapolith = inverted (concave down) muschroom, concordant
a large mass of igenous rock that formed when magam was emplaced at depth, crystallized an subsequently exposed by erosion.
greater than 100km2
like batholiths, less than 100km2
What five areas (disciplines) of research contribute significantly to neogeomorphology?
Contast Shield Volcanoes with Stratavolcanoes?
Relative magma comp. {0} (med)
Magmat temp. {hot} (med)
visco. {low} (higH)
Discuss shear stress vs. shear strength.
Shear Stress forces that tend to induce downward movemeny, exerted by gravity
-addition of h20
-loading of slopes
-removal of support
opposing forces act to resist downslope movement
-plant roots
List and discuss the 4 physicasl factors that are used to help predict volcanic eruptions?
Seismic Activity
-magma fractures rock producing shallow focus earthquakes
-continuous vibrations
Swelling and Tilting
-bulging of landsurface as magma rise
-deflation occurs in area where magma has been withdrawn
Monitoring of Volcanic Gases
-increase in sulfur emissions
Changes in Thermal, Electricla and
-Temp increase
-Mand E change
-heat affects viscosity affects density affects gravity
List three types of Stress that affect Earth. ex.
Compressional = reverse fault
Tensional = normal fault
Shear = strike-slip fault
What is an antecedent stream? What is a superimposed stream? How do they differ?
Antecedent Stream
-stream is established before a slow uplifgt occurs
-continues downward erosion as uplift continues
-stream maintains original pattern
-stream older than structure it flows through
-results in deep gorge
-a river develops its pattern on rock layers, which are then removed by eorison
-river is now flowing over older rocks that have been uncovered
-these rivers are youngers that the structres that they flow through
What are fault scarps?
steep linear bluffs produced by tectonic offsetting of the land surface along the trace of faults (escarpments)
-hanging valleys
-alluvial fants
-wineclass structrures
-sagponds = an area between 2 parallel fault zones that has dropped down creating a depression that can fill with water
Hawaiian Type
type fed by the outpouring of basaltic lavas in the hawaiian islands (shield volcanoes)
-characteruzed by rekatuivelky quiet emission of large volumes of fluid basalt
the magma is hot amd mobile alowing gases to escape without violence
Icelandic Types
fissure eruption
divergent boundary
tensional stress
basaltic lava = hot/mobile
cretea extensive lava platueas
gravel sized pyroclastic material 2-64mm, angular
Debris Flow
Mud Flow
a flow of soil and regolith containing a large amount of water, most commin in semiarid mountainous regions and on the slopes of some volcanoes
Earth Flow
the downslope movement of water-satureated, clay-rich sediments
most occur in humid regions
a huge mass of rapidbly moving rock debris and dust, derived from the collapse of a cliff or mountain side, flowing downsteep slopes and across lowground, often for several kilometers at speeds of more than 100km/hr
-sturzstroms are most catastrophic
-like cold nuee ardent
debris avalanche
unsorted, incoherent mixtures of soil, sediment rock (with water, ice or both) that move rapidly down steep slopes after a mass of snow or satureated groun has broken loose
the downward slipping of a mass of rock or unconsolidated material moving as a unit along a curved, concave upward, surface
-characterized by rotational movement semicircular glidplan
occur when rock breaks loose from steep slopes and falls though the air to the ground
-movement is largely by free fall through the air but may also include some bouncing or rolling
occurs when blocks of bedrock break llose and slide down a slope (planar surface)
-they are one of the fasted and most destructive types of mass wasting
(IF material is unconsolidated, debris slide is the correct term)
the slow downslpe movement of superficial soil or rock devbris usually impercetible except of observations of long duration DO NOT NEED WATER
the downslope flowage of saturated soil. it results from water...beinga ble to infiltrate because of some type of subsurface bariier, dense clay/frozen layer
(DOES not need to be glacial)
classifying mass wasting events
type of material, type of motion, date of movement, degree of saturation
Snow Avalanche
same as Debris flow
Krakatoan Type (Ultra Plinian)
the most violently explosive type of eruptiosn, longer period of rising gas, starts deep, deep degassing results in a more explosive, and violent eruption, named after Krakato volcano,
1980 mt. st. helen
Plinian Type
composite cone/strata
explosive eruption of gas and pyroclastic material (tefra)
mount vesuvius is most famous example
huge clouds that extend 165000 to 200000 feet in the air
cone of gas, straight up
seen in alaska and mexico

Deck Info