review of minerals and rocks
ionic and covalent bonding
the dipolar nature of water molecules
how water molecules dissolve ionic solids (they hydrate ions)
silica, silicate minerals
how silicates are put together:
varying proportions of silica (more covalent) "glued" together with metal cations (more ionic)
the more silica (covalent) the more resistant to weathering; the more cations the less resistant
general composition: mafic, intermediate, felsic
weathering stability of silicate minerals in terms of relative degree of ionic vs. covalent bonding
weathering:
mechanical weathering: frost wedging, crystal growth, root wedging, abrasion: stream abrasion, sand blasting
chemical weathering: acidification of water, hydrolysis, dissolution, biological agents: chelation, organic acids, plant roots
controls on weathering:
parent material, climate, vegetation, topography, time
weathering stability of mafic vs. felsic, sandstone vs. limestone vs. shale, igneous vs. sedimentary rocks
some landforms caused by differential weathering: cliff and bench, valley and ridge
soils:
soil forming processes
weathering, incorporation of organic matter, downward leaching
soil profile
A,B,C horizons and their characteristics
angle of repose
gravity vs. friction vs. slope
factors leading to slope failure
processes that can increase shear stress (loading, building, water load)
processes that can decrease effective normal stress (increased pore pressure - saturation)
water saturation - increases weight & driving force, pore pressure reduces effective normal stress
oversteepening: building or ersional undercutting
vibration: earthquakes and building (e.g., pile drivers) can cause compaction
compaction decreases pore space, increases pore pressure
weathering: decreases rock strength by jointing and dissolving cements
types of mass wasting
creep & flow
creep: soil creep, solifluction, rock glaciers
earthlows
debris flows & mudflows
lahars (volcanic mudflows)
slides
slumps
rockslides & debris slides
rock falls
surzstroms
hillslope morphology
upper slopes are convex-up: infiltration high; creep dominates
lower slopes are concave-up: runoff high; sheet wash and rill wash dominates
noses & hollows
water is concentrated in hollows: inreased weathering and erosion
water is diffused on slopes of noses: decreased weathering and erosion
hydrologic cycle
precipitation = infiltration + runoff + evapotranspiration
runoff: sheet wash, rill wash, gullies, streams
stream characteristics
velocity
velocity profile in a stream (slowest on bottom & sides, fastest just below surface)
width & depth -> cross-sectional area
discharge, Q = velocity * area
hydraulic radius: HR = area / wetted perimeter
HR measures streams' efficiency - ease of flowing (driving force vs. friction)
relationship between velocity, slope, and roughness
shear: velocity gradient from bed up into stream
steeper velocity gradient (shear) can more easily set particles in motion from stream bed
increase slope->increase depth->increase shear
laminar vs. turbulent flow (and ability to suspend sediments
stream hydrographs
storm charge, baseflow
streams and groundwater
gaining (effluent) streams
losing (influent) streams
stream loads
bed, suspended, and dissolved loads
competence & capacity (relationship to velocity, shear, and discharge)
significance of 6th power law for velocity & competence
stream load affected by:
local topographic relief, lithology, climate, vegeation
meandering streams
how/why
the depth and velocity profile across a bend from inner bank to outer bank
point bars, cut banks, oxbow bends, oxbow lakes
sinuosity, meander wavelength, radius of curvature
and relationship to stream discharge and width and nature of bank materials (esp. clay & silt content)
stream width vs. clay & silt content of bank material
braided streams (intro)
easily eroded bank materials (low in silt & clay; high in sand & gravel)
broad shallow streams
braided streams
easily eroded bank materials (low in silt & clay; high in sand & gravel)
broad shallow streams (low hydraulic radius, high friction)
steeper gradient develops to overcome friction and continue to transport the coarse load
graded streams
local gradation (how a stream gradually removes abrupt changes in slope via erosion and deposition)
the ideal graded profile (concave up)
how & why it is maintained that way (changing downstream discharge & hydraulic radius)
the graded stream is in equilibrium (just transports, doesn't erode or deposit seds on average)
effects of changing base level (sea level rise/fall) and changing elevation of source (uplifts)
stream valleys
stream terraces: develop as streams try to readjust grade to uplifted headland or drop in base level
flood plains, valley walls, natural levees
convex stream valleys, yazoo streams, backswamps
stream networks
stream order, basin order, divides
morphometric parameters
number of streams vs. stream order
average stream length vs. stream order
average slope vs. stream order
average drainage area vs. stream order
drainage density
midterm exam
deltas
distributaries
topset, foreset, and bottom set beds
sediment supply vs. subsidence and sea level rise
alluvial fans
Basin and Range, fault block ranges
concave-up, coarse on top -> fine below
bajadas, playas
pediment
karst
soluble rocks: limestone, dolomite, marble, halite
karst chemistry: dissolution of limestone
biological factors: that enhance dissolution
mixing zone chemistry: where most dissolution occurs
karst dissolution cont'd
climate factors: deserts, cold regions, temperate, tropical
structural control (joints & bedding parting)
karst features
sinkholes (dolines, cenotes)
sinkholes, swallow holes, blind valleys
pocket valleys, karst (solution) valleys
landscape transition from fluvial to karst
fluviokarst and holokarst
tropical karst
cockpits
residual kast
tower karst
cone karst
cave systems
dripstones: stalactites & stalagmites
review of tectonic plate boundaries and associated stresses
plate boundaries: divergent, convergent, transform
stresses: tension, compression, shearing
review of geologic structures
compression: thrust and reverse faults, and folds
extension: normal faults
shearing: strike-slip faults
landforms associated with thrust and reverse faults
thrust belts, foreland basins
landforms associated with normal faults
basin and range topography, internal drainage, playas
half grabens (ancient Newark Basin, modern African Rift valleys)
landforms associated with strike-slip faults
offset streams
shutter ridges
releasing bends: pull-apart basins; restraining bends: push-up ranges
landforms associated with flat-lying strata
dendritic stream networks (also found in homogeneous crystalline rocks)
resistant layered rocks: sandstone, conglomerate, limestone (arid), lava flows, sills
non-resistant layered rocks: shale, limestone (humid)
cliff and bench topography
esplanades
buttes and mesas
landforms associated with tilted strata
valley and ridge topography
scarp slope, dip slope
water gaps, wind gaps
landforms associated with tilted strata (cont'd)
consequent & subsequent streams
homoclinal shifting
homoclinal ridges
cuestas & hogbacks
landforms associated with folds
mostly homoclinal ridges as above
topography due to non-plunging vs plunging folds
domes & basins
landforms associated with faults - general
fault scarps, triangular facets
hanging valleys & wineglass structure
alluvial fans
drag folds
fault splays, fault slices, slumping
landforms associated with crystalline rocks vs. sedimentary rocks
Newark Basin
half graben with sedimentary strata and basaltic lava flows and sills
strata and flows tilted gently to WNW
homclinal ridges upheld by basalt (crystalline rock), valleys floored by sandstone and shale
Metamorphic (Hudson) Highlands
resistant massive, granitic (felsic), gneiss (crystalline rock) stands high relative to sedimentary lowlands
glacial process
making ice: snow, firn, glacial ice
glacial flow & basal sliding
crevasses
polar and temperate glaciers
ice sheets and ice caps
alpine: cirque, valley, tidewater, and piedmont glaciers
mass balance - accumulation vs. ablation
glacial erosion and erosional landforms
erosion via abrasion and plucking (quarrying)
glacial striations
nivation basins, cirques and tarns
horns, arêtes, cols
U-shaped or parabolic valleys
hanging valleys and waterfalls
glacial erosional landforms cont'd
U-shape or parabolic valleys
fiords
finger lakes
roches moutonées
glacial deposition and depositional landforms
glacial transport and deposition
glacial till & erratic boulders
moraines
terminal
lateral
medial
recessional
ground
dead-ice
interlobate
drumlins
varves
eskers
outwash plain
kettle
coastal processes - background review
the coastline is shaped by waves, tides, storms, and rising sea level
sea level rising 1-2 mm/yr
results in nearly 1 m/yr landward movement of shoreline on very gently sloping shore like eastern U.S.
waves: produced by wind
orbital motion down to a depth of L/2
breaking waves: slows down when water depth less than L/2
waves get shorter, steeper, and higher
swash and backwash
longshore drift
coastal erosional landforms
sea cliffs
wave-cut notch
wave-cut platform
sea stacks
caves -> sea arches
coastal depositional landforms
beaches
longshore bars
longshore troughs
foreshore
summer berm
winter berm
dune
beach cusps
spits
barrier islands
washover fan
marsh & lagoon
inlets
flood-tidal deltas
ebb-tidal deltas
types of coastlines
shorelines of submergence
deeply embayed, irregular coastline with many islands
drowned valleys
shorelines of emergence
straight shoreline
marine terraces
coral reefs
fringing reefs
barrier reefs
coral atolls
final exam