bullshit 1 Flashcards
21,000 years ago the world was ___% of ice
30%
now the world is ___% of ice
10%
__% of world’s freshwater is stored in antarctic / Greenland ice caps.
75%
area where a glacier forms
zone of accumulation
area where there is a net loss of glaciers due to melting
zone of ablation
pressure of ice causes bottom to melt which lubricates it. Like ice skates on ice - whole glacier moves relative to ground
basal slip
head of a glacial valley, with nearly vertical upper walls and a flat or hollowed out base
cirque
sharp jagged crests along an eroded divide
aretes
U shaped valley occupied by an arm of the sea
fjord
all sediments of glacial origin
drift
material that is deposited directly by ice
till
sediment deposited by meltwater
stratified tilt
till is usually ______ and poorly _____
unstratified and poorly sorted
layers or ridges of till
morraines
types of till
lateral, medial, end, ground
examples of glacial Lorraine deposits
nantucket, Martha’s Vineyard, long island
examples of depositional features from glacier deposits
outwash plain, kettles, drumlins, eskers, varves
when do drumlins, eskers, and kettle lakes form?
after complete deglaciation
migration of plants / animals
rebounding upward of crust
wordlwide change in sea level
climatic changes
indirect effects of ice age glaciers
Variations in earth’s orbit were declared in
milankovitch hypothesis
what did the milankovitch hypothesis state
shape (eccentricity) of earth's orbit varies angle of earth's axis (obliquity) changes axis wobbles (precession)
successful theory for glaciations must account for
cooling of earth and short-term climatic changes
proposed possible causes of glaciations
plate tectonics - continents arranged differently
changes in ocean circulation
milankovic cycles
sea levels only rise if
melting ice is on land
factors that affect wind / wave development
wind strength
wind duration
fetch
what must the wind strength be for the energy transfer to continue
winds must be moving faster than the wave crests
do winds that blow for a short time generate large waves?
no
the uninterrupted distance over which the wind blows without changing direction
fetch
how to describe a wave
wave hight, wave length, and period for successive waves.
velocity of a wave
wavelength / period
what happens when a wave approaches the shore
wave speed decreases, wave length decreases, wave heigh increases, wave breaks
currents that are parallel to the shore
longshore currents
currents that are perpendicular to the shore
rip currents
caused by wave impact and pressure
breaks down rock material and supplies sand to beaches
wave erosion
height of tides are affected by
earth-moon-sun alignment, shoreline configuration, tidal surge with storms
____ of waves stay approximately aligned with moons
bulging
examples of erosional coastal forms
sea cliffs and wave-cut terraces
what is the effect on beaches due to sea-level change due to warming/melting of ice caps and expansion of water in oceans
net erosion and loss of the beach
uplift of land or a drop in sea level
emergent coast
examples of an emergent coast
wave-cut cliffs / marine terraces
land adjured to sea subsides / sea level rises
submergent coasts
drowned river mouths
estuaries
submergent coasts have
highly irregular shorelines
why are coastlines different
tidal waves, wave heights, tectonics, coastal currents
study of ocean floor contours
bathymetry
how did bathymetry initially start off
heavy weight on end of rope
advances in bathymetry include
echo sounding
multi beam system
satellite altimetry
speed of sound in water
1500 m/sec
measured depth is less than
actual depth
multi beam systems essentially
mow the lawn
disadvantage with multi-beam systems
only 200 of them, would take around 125 years
what is used now for bathymetry
topex / poseidon
advantage of topex/ Poseidon
underwater features create gravitations pull on seawater and induce variation in sea surface height
3 major topographic units on the ocean floor
continental margins
ocean basin floors
mid-ocean ridge
passive congenital margins tend to have ___ continental shelf regions
big
marks the seaward edge of the continental shelf
contiental slope
the continental slope has a relative ___ structure
steep
found in regions where trenches are absent
continental rise
the continental slope merges into a more gradual incline which is
the continental rise
at the base of the continental slope, there are _____ ___ that follow submarine canyons that deposits sediment that forms deep sea fans
turbidity currents
extends from shoreline to shelf break
continental shelf
wide gently sloping (1:1000)
continental shelf
extends from break to rise
continental slope
relatively steep (1:40) (unstable)
continental slope
extends from slope to abyssal plain
continental rise
intermediate (1:100 to 1:700)
continental rise
deep, steep-sided valleys cut into the continental slope
submarine canyons
down slope movements of dense, sediment-laden water
turbidity currents
formed by erosion from turbidity currents
submarine canyons
continental slope descends abruptly into a deep ocean trench
located primarily in pacific ocean
active continental margin
what makes up half the earth’s surface
deep ocean basins
long, relatively narrow features
deepest parts of the ocean
associated with volcanic activity
deep ocean trenches
interconnected ridge system that is the longest topographic features on earth’s surface
mid-ocean ridges
takes up 23% of earth’s surface
mid-ocean ridges
thin sediment of mountainous chain of young, basaltic rock at an active ,spreading center of an ocean
mid-ocean ridges
along axis of some mid-ocean ridges are deep, normal fault structures called
rift valleys
flat, featureless expanses of sediment floor found between margins / ridges
abyssal plains
small, extinct volcanoes or rock intrusions near ocean ridges
abyssal hills
volcanic projections from ocean floor that are not above sea level
seamounts
chains of volcanic islands and seamounts found parallel to edges of ocean trenches
island arcs
found on ocean floor at mid-ocean ridges
pillow basalts
sites where superheated water containing dissolved minerals and gasses escape through fissure or vents
hydrothermal vents
range around 350 degrees C
play important role in chemical composition of seawater
discovered in 1977
very little dissolved magnesium is found in vents
hydrothermal vents
seawater contains high concentrations of ______
magnesium
as seawater circulates through _____, magnesium is removed
basalt layers
circular, coral islands in the middle of the ocean
atolls
deep sea sediment’s 2 main sources
external - terrigeneous (land)
internal - biogenic (formed by organisms)
economic value of ocean sediments
oil / fossil fuels, salt, and phosphorous deposits
determine shape / structure of the bottom of the ocean and shows chronological history
ocean sediment
5 categories for sediment
terrigeneous (land) biogenic (organisms) authigenic (precipitates formed in place) volcanogenic (from volcanoes) cosmogenic (from space)
factors that control sedimentation
particle size and depositional environment
strongly reflect their source and are transported to the sea by wind, rivers, and glaciers
terrigeneous sediments
average grain size of sediment in the ocean is equivalent to
energy of depositional environment
most important biogenic sediments
silica (opal) and calcium carbonate
silica occurs in areas of abundant ___
diatoms
foraminifera (calcite) is less ___
soluble
pteropods (aragonite) is more ___
soluble
dissolution is highest in ___ waters
deep
dissolution is highest in deep waters because
high pressure, low temperatures, low PH (high CO2)
“new” deep waters have ____ CO2 concentrations
low
“Old” deep waters have ____ CO2 concentrations
high
pacific deep waters are ___ than Atlantic deep waters
older
abundant in pacific / south Atlantic oceans
authigenic deposits
distribution of sediments in deep ocean depends on
latitude
distance from land masses
CCD
in mid 1600s, concluded Earth was only a few thousand years old
James Ussher
Created theory of the earth in late 1700s
James hutton
the theory of the earth stated what
recognized catastrophes are apart of thes law
style of geologic processes have changed
fundamental principle of geology “the present is the key to the past”
uniformitarianism
determining when a geologic age formed relative to other geologic features
relative age
determining when a geologic event occurred in exact units of time
radiometric ( absolute ) age
oldest rocks on the bottom
law of superposition
sediment is deposited horizontally
principle of original horizontality
younger feature cuts through an older feature
principle of cross-cutting relationships
rocks being “baked” are ___
older
rocks containing another rock is
younger
dikes cut through ____ rocks
older
break in rock record
indicate a gap in time
unconformity
missing time between horizontal sedimentary layer
disconformity
missing time between two sets of strata that are not parallel to each other
angular unconformity
unconformity between igneous or metamorphic rocks and younger sedimentary rock
nonconformity
spontaneous breaking apart (decay) of atomic nuclei
radioactivity
measures the amount of parent and daughter material is a
mass spectrometer
how to calculate age for radioactivity stuff
of half - lives elapsed(half-life of system)
half-life of 5730 years
used to date very recent events
produced in upper atmosphere
carbon - 14 dating
greatest expanse of time
eons
4 eons
phanerozoic
proterozoic
archean
hadeon
divisions of time
eon –> era –> period –> epoch
eras of the Phanerozoic eon
Cenozoic ~ recent life
mesozoic ~ middle life
Paleozoic ~ ancient life
Urey miller experiment proved that amino acids can be produced how?
abiotically
origin of ocean
water vapor condensed to form clouds and rain water that formed the oceans
fossilized layered mounds
stromatolites
Precambrian history composes how much of earth’s history
90%
the Precambrian history is divided into the __ and __ eons
Archean and Proterozoic eons
during this time, much of the continental crust was formed into cartons (larger blocks)
precambrian history
might have proceeded pangea
rodinia
this eon encompasses 542 million years
Phanerozoic hisotry
this era was dominated by Pangea assembly
Paleozoic era
what was before pangea
gondwana
marked first appearance of life forms with hard parts
mainly restricted to the sea
paleozoic era
insects / plants moved to land
first amphibians
paleozoic era
much of the land is above sea level
sea invades western NA
pangea begins to break, west-ward moving NA plate overrides pacific plate
mesozoic era
aga of dinosaures happened when
mesozoic era
gymnosperms and dominant trees formed
reptiles were dominant land animals
during when did this happen?
mesozoic era
Cretaceous - tertiary (KT) boundary (K-Pg)
extintction event at end of mesozoic era
age of flowering plants (angio sperms)
Cenozoic era
unsaturated zone (weathered bedrock) pore spaces in the material are filled mainly with air
zone of aeration (vados zone)
porous bedrock (sandstone)
all pore spaces in material are filled with water
water within the pores is ground water
zone of saturation (phreatic zone)
the upper limit of the zone of saturation
water table
an impermeable layer of material (acquiclude)
aquitard
a permeable layer of material
aquifer
un-cemented, well-sorted, fractured -
more porous
the way for space is connected
tortuosity
large connected pore spaces =
high permeability
small, disconnected pore spaces =
low permeability
permeability depends on
grain size and packing
____ material is more permeable than fine-grained sediments
coarser
helps determine pore space
sorting
defines connectivity
grain shape
controls pore size
packing
aquifer that has an aquiclude below
unconfined
aquifer that has an aquiclude above and below
confined
an ____ aquifer can produce an artesian well
inclined
____ of freshwater keeps saltwater margin slightly offshore
pressure
how does a steep-slope affect infiltration
much run-off , poor infiltration
how does a gentle slope affect infiltration
little run-off, much infiltration
how does heavy precipitation affect inflitration
ground surface saturated, poor infiltration
how does vegetation affect infiltration
sparse = good dense = poor
infiltration (good –> bad)
gravel, sand, clay
darcy’s law
volume of water = cross sectional area of flow(permeable conductivity X (vertical drop / flow distance))
larger vertical drop =
higher flow rate
longer distance
= lower flow rate
higher permeability =
higher flow rate
hot springs are heated by
cooling of igneous rocks
formed by dissolving rock beneath earth’s surface
caverns
caverns are formed in the zone of
saturation
calcite fizzes in ___ when it dissolves
acid
when water enters an open cavern, concentrations of dissolved CO2 in waters ___ and calcite precipitates
drop
cavern features are formed in the zone
of aeration
stalactites -
hang from ceiling
stalagmites
growing upward from the floor
land features in areas impacted by cave formation
karst topography
air rises at the equator due to ___ at earth’s surface
heating
when air cools enough, water vapor in the air will
condense to form liquid rain
where are deserts found
near 30 N and 30 S
plays a role in formation of deserts
plate tectonics
climate change
human actions
factors in how wind carries things
wind strength
particle size
surface material
crescent shaped dunes, usually in groups, horns of crescents point downwards.
found with limited sand supply
concave downwards
barchans
reverse of butanes, slip face = convex downwind
blowout dunes
long ridges oriented at right angles to wind direction form in arid regions surplus of sand absent vegetation usually behind beaches
transverse dunes
long ridges of sand parallel to wind
can reach super high ~ 100 m
wind always in same direciton
longitudinal dunes
deposits of wind silt
extensive blanket deposits
primary sources are deserts / glacial stratified drift
loess
mounds and ridges of sand formed from the wind’s bed load
sand dunes
the leeward slope of the dune
slip face
sloping layers of sand in the dune
cross beds
during chemical weathering in arid climates
clay forms
thin soil forms
desert streams are called
wash, arroyo, wadi, donga, nullah
flow only during periods of rainfall
ephermal
desert streams are said to be
ephermal
large knobs of bedrock projecting from a sediment filled basin
inselbergs
interior drainage into basins of a desert landscape produce
alluvial fans / bajadas
playas and playa lake
