Lecture 2 Flashcards
Permafrost
soil and sedimentation that have remained frozen for two or more consequtive years
active layer of soil( in terms of permafrost)
is the seasonally frozen ground on top of subsurface permafrost-thaws every summer
in winter the active layer freezes, trapping plant and animal material before it can decompose completley
-creates carbon rich soils
carbon in permafrost is ___ the ammount stored in the atmosphere
twice
endogenic system
exogenic
consists of proccesses operating in earths interior driven by heat and radioactive decay
processes operating at earths surface driven by solar energy and movement of air, water, and ice
eons
eras
periods
epochs
largest time span
Shortst
EpochHolocene
Eon: phanerozoic
the current era is the _______
cenozoic(quaternary period)
Earths core is a / of earths mass and a / of its volume
1/3, 1/6
inner and outer core are seperated by th ______ zone
inner core is solid ____
outer core is _____
Outer core is seperated from mantle by a transition zone seveeral hundred km wide at a depth of ____
lower and upper mantle represent __% of earths volume
transition
iron(remains solid despite heat because of pressure)
molten, metalic iron with lighter density
2900km
80
________ discontinuity occurs at a depth of about 2900k between outer core and lower mantle
________ discontinuity occurs between uppermost mantle and crust
Glutenburg
Mohorovicic(moho)
-seismic waves change at this depth due to sharp contrasts in material composition and density
7 segments of earths depth(deepest to shallowest)
Inner core Outer Core Lower Mantle Upper Mantle Asthenosphere Uppermost Mantle Continetal Crust
crustal thickness is thickest beneath ______ at 50-60km
30 km thickness beneath _______
5km thickness beneath _______
mountain
continental
oceanic
______ and _____ make up __% makes up earths crust
Oxygen and silicon
74%
-more oxygen in crust than atmosphere
continental crust is ___ in density in comparison to oceanic= 2.7 vs. 3.0
Continental composed of ______
oceanic composed of _______
lower
Granite
Basalt
Lithosphere vs Asthenosphere
- Rigid Layer
- crust and uppermost mantle to about 70 km
- plastic layer
- within mantle from 70km to 250km
- convection currents in this zone in part causes the shifting of lithospheric plates
Are crust and lithosphere the same?
No, the crust makes up the upper portion of the lithosphere
isostasy
the balance between the buoyancy and gravitational forces
-explains elevations of continents and the depths of ocean floors as determined by vertical movements of earths crust
isostatic rebound
if the load is removed, such as when a glacier melts, the crust rides higher and the astenosphere flows back toward the region of uplifting lithosphere
Earths fluid outer core generates most of earths ______ field
magnetic
-circulation in the outer core converts thermal and gravitational energy into magnetic energy
95% o earths crust is made up of ______
silicates
Igneous Rock
one that solidifies and crystallizes from a molten state
- makes up approximately 90% of earths crust
- coarse if beneath the surface like granite
- finer grained from fast cooling at surface is basalt
Pluton
.intrusive igneous rock that cools slowly in the crust forms…
-largest plutonic form is Batholith
Sedimentary Rock
-4 types
.Driven by solar energy and gravity
1.Clastic:Weathering, Deposition, Lithification
- Biochemical:dissolved minerals build up to form rocks
- ex:limestone - Organic:
- Chemical:dissolved minerals build up to form rocks
CAN BEES OPEN CANS?
Lithification
occurs as loose sediment is hardened into solid rock
Metamorphic
.any igneous or sedimentary rocks can be transformed into metamorphic by going through physical and chemical changes under pressure and increased temp
caused by: heating, pressure, heating and pressure together, and compression and shear
Foliated rock
has a banded or layered appearance
Geological cycle made up of three main internal cycles:
Hydrological
Rock
Tectonic
3 orders of relief
- Continents and oceans
- intermediate level of landforms like mountain masses, underwater continental rises
- most detailed order of relief includes individual mountains, cliffs
Hypsometry
Bathymetry
measurement of land elevation relative to sea level
same thing but underwater
Earths diameter in km?
Average elevation of earths solid surface?
12,756 km
-2070 m so under sea level
.oceans are much deeper than continents are high
Subduction and connected eruptions, which may not reach the surface, are ____ rich in comparison to eruptions that come straight from the aesthenosphere
silica
terranes
pieces of land mass which eventually becomes a part of continents
crustal deformation caused by 3 things
___ is the measure of the ammount of deformation undergone by an object
- Tension=causes stretching
- -Normal fault - compression: causes shortening
- causes folding(think of pushing cloth in together on both sides)
- Thrust or Reverse fault - shear: causes twisting or tearing as objects slife parallel to one another
- strike-slip fault(lateral shearing)
Strain
Faulting
occurs when rocks on either side of the fracture shift relative to the other side
Orogenesis
caused by 3 things
geological term for mountain building
. folding, faulting, and volcanism
3 different types of lithospheric plate collisions result in mountain building
- oceanic plate continental plate
- subduction zone forms
- magma erupts to the surface through continental plate, vlcanic mountains form.
ex: andes of south america - oceanic-oceanic
- subduction zone forms
- magma forms above the descending plate, giving rise to volcanic island arc
ex: Japan - continential-continental
- neither plate is subducted
- powerful compression force folding,faulting, and uplift pushing up huge mountain ranges
ex: Himilayas
Tectonic earthquakes are those quakes associated with _______
faulting
The pacific coasr is the most seismically active region in canada, one of the few regions in the world where _____,_______, and ______ plate boundaries occur in proximity to one another
transform, divergent, convergent
Elastic Rebound Theory
when two sides are locked in position by friction, eventually elastic energy is so built up when it releases it is huge
Volcanic Activity occurs in three settings
Along subduction boundaries at continental plate-oceanic plate convergence
along sea floor spreadinf centert on the ocean floor
hot spots
Effusive Erruptions
Explosive Volcanoes
are ourpourings of low viscocity magma that produce enourmous volumes of lava annually on the seafloor and in places such as Hawaii and Iceland.
- flow directly from aestenosphere and upper mantle
- low in silica, high in iron
are violent explosions of magma driven by the buildup of pressure in magma conduit
- created by subducting plate and other thicks materials than magma which forms effusive volcanoes
- material blocks magma conduit by forming plug and only releasing after much built up pressure
- much less lava than effusive, but larger ammounts of pyroclastics like volcanic ash
- a mountain produces by a series of explosive volcanoes is called a composite volcano or stratovolcanoes because of many layers
ex: Mount St.Helens, Cali
scarification
results from such human cause mass movements instead of gravity as the agent which drives natural processes, most mass movement related to human accitivity is done by machines and the burning of fossil fuels
Weathering vs Erosion
is the break down of materials
transport of weathered materials to different locations
Denundation
is any process that wears away or rearanges landform
geomorphic threshold
tipping point, where the system lurches to a new operational level when abrupt change occurs
the upper surface of bedrock undergoes continual weathering, creating broken up _____
REGOLITH
sppheroidal weathering
is chemical weathering that softens and rounds the sharp edges and corners of jointed rock as water penetrates the joints and dissolves weaker minerals or cemmenting materials
Karst topography
certain areas of the worl with extensive lime-stone formations, chemical weathering involving dissolution of carbonates dominates entire landscapes
ex: limestone
- sinkholes,karst valleys(bunch of sinkholes together),caves and caverns, towers
- limestone formations must contain 80% or more calcium carbonate
- complex patterns of joints in the otherwie imperiable limestone
- aerated zone must exist between ground surface an water table
- vegetation covers is needed to supply varying ammounts of organic acids
define mass movement/mass wasting
downslope movement of a body of material made up of soil, sediment, or rock propelled by the force of gravity
-can occur on land or underwater