Jan 24, 2002
review of minerals and rocks
silica; mafic, felsic
ionic and covalent bonding (and weathering stability of ionic and covalent solids)
weathering:
mechanical weathering: unloading, exfoliation, frost-wedging, crystal growth, salt hydration-dehydration, thermal expansion & contraction, root wedging, wetting & drying in clays (esp. montmorillonite), impact: stream abrasion, sand blasting
chemical weathering: carbonation, hydrolysis, dissolution, oxidation, biological agents: chelation, organic acids, plant roots
weathering features: jointing - exfoliation, niches, cliff & bench topography, frosted sand grains, ventifacts
Jan 31, 2002
controls on weathering:
parent material (mineral and rock stability, porosity, jointing), climate, vegetation, topography, time
weathering features:
granular disintegration (grus), weathring pits, speroidal weathering, inselbergs and tors
soils:
soil forming processes (weathering, incorporation of organic matter, downward leaching)
soil profile (A,B,C horizons), caliche (calcrete)
characteristics of soils in different climates (temperate, tundra, desert, tropical)
angle of repose and mass wasting:
forces acting on a block on an inclined plane (gravitational force, shear force, normal force)
friction acts with the normal force resist the shear force applied by gravity
stress (force/area)
processes that can increase shear stress (loading, building, water load)
processes that can decrease effective normal stress (increased pore pressure - saturation)
categories of mass wasting: flow vs. slip
Feb 7, 2002
factors leading to slope failure
water saturation - increases weight & shear stress, pore pressure reduces effective normal stress
oversteepening: building or ersional undercutting
vibration: earthquakes and pile drivers
accelerate particles (dynamic friction less than static friction)
compaction decreases pore space, increases pore pressure
may lead to liquefaction
weathering: decreases rock strength by jointing and dissolving cements
types of mass wasting
flows
creep: soil creep, solifluction, rock glaciers
earthlows
debris flows & mudflows
lahars (volcanic mudflows)
slides
slumps
rockslides & debris slides
rock falls
struzstroms
hillslope morphology
upper slope convex-up: infiltration high; creep dominates
lower slope concave-up: runoff & sed transport & deposition dominates
noses & hollows
water concentrated in hollows: inreased weathering and erosion
water diffused on slopes of noses: decreased weathering and erosion
February 14, 2002
stream processes
discharge
hydraulic radius
recurrence interval (predicting floods)
recognition of paleofloods (slack water deposits, overbank deposits, bank vegetation, boulders, etc.)
velocity effects
laminar vs. turbulent flow
velocity profile in a stream (slowest on bottom & sides, fastest just below surface)
shear (velocity gradient) near bottom & its effect on ability to erode sediments
slope effects
increase slope->increase depth->increase shear
stream loads
bed, suspended, and dissolved loads
channel types
meandering, straight, braided
stream hydrograph
storm charge, baseflow
streams and groundwater
gaining (effluent) streams
losing (influent) streams
February 21, 2002
graded streams
stream gradation (how a stream removes steep stretches and fills in flat stretches)
the ideal graded profile (concave up)
how & why it is maintained that way (changing downstream discharge & sediment size)
effects of changing base level (sea level rise/fall) and changing elevation of source (uplifts)
stream valley evolution
youth (steep sided, V-shaped, no flood plain)
early maturity (gentler slopes, beginning of flood plain)
full maturity (meandering stream, oxbow lakes)
old age (very low gradient, flood plain much wider than meander belt)
meandering streams
how/why
point bars, cut banks, oxbow bends, oxbow lakes
stream valleys
flood plains, valley walls, natural levees
stream terraces
February 28, 2002
braided streams
large sediment supply (coarse sediments: sand and gravel)
easily eroded bank materials (low in silt & clay; high in sand & gravel)
broad shallow streams
steeper gradient develops to transport the coarse load
cycle of eosion
youthful: rugged topography, V-shaped valleys, perhaps some remnent original surfaces (penneplain)
mature: gentler rolling topography, meandering streams
old age: very low relief surface approaching base level (penneplain)
rejuvenated: uplifted penneplain with meanders cutting down into steep-sided V-shaped valleys
large-scale fluvial depositional landforms
alluvial fans, coalesced fans (apron)
deltas
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
March 14, 2002
groundwater in brief
porous, permeable
aquifers and aquicludes
water table, zone of saturation, zone of aeration
relationship between groundwater and surface water (gaining/effluent and losing/influent streams)
gaining streams as groundwater discharge locations
streams, lakes, wetlands
springs
introduduction to karst
soluble rocks
karst chemistry: carbonation; dissolution of limestone
effect of disturbing the reaction at equilibrium for example via flushing with ample groundwater flow (LeChatelier's Princ.)
structural control (joints & bedding parting)
March 21, 2002
karst: factors in dissolution
host rocks
sources of acids for karst: atmospheric CO2, soil CO2 from decay, organic acids
chemistry: mixing
climate factors: deserts, cold regions, temperate, tropical
major karst features
sinkholes (dolines)
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
April 4, 2002
review of tectonic plate boundaries
divergent, convergent, transform
stresses associated with plate boundaries
tension, compression, shearing
review of geologic structures
primary structures: bedding, lava flows
secondary structures:
joints
faults: normal, thrust, reverse, strike-slip
folds: anticlines, synclines, plunging and non-plunging fold axes
foliation: slaty cleavage, schistosity, gneissic banding (only important in small-scale structures)
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
April 11, 2002
landforms associated with tilted strata (cont'd)
consequent & subsequent streams
homoclinal shifting
homoclinal ridges
cuestas & hogbacks
landforms associated with folds
sometimes anticlinal ridges, synclinal valleys
mostly homoclinal ridges as above
form of 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 normal faults
fault block mountains
basin & range topography (horst & graben)
internal drainage - desert playas
tilted fault block mountains
half-grabens (east African rift, Newark structural basin)
landforms associated with strike-slip faults
offset streams
shutter ridges
releasing bends: pull-apart basins; restraining bends: push-up ranges
April 18, 2002
glacial process and landforms
making ice
glacial flow & basal sliding
polar and temperate glaciers
ice sheets, alpine, and piedmont glaciers
mass balance - accumulation vs. ablation
erosion via abrasion
nivation basin and cirques & tarns
crevasses
U-shaped or parabolic valleys
hanging valleys
fiords
terminal, lateral, and medial moraines
April 25, 2002
glacial process and landforms
glacial striations, grooves, polish
horns, arêtes, cols
rock steps and pater noster lakes
roches moutonées
finger lakes
glacial till
characteristics of glacio-marine, glacio-fluvial, glacio-lacustrine, and glacio-eolian deposits
varves, loess, catabatic wind
dead-ice moraines, recessional moraines, ground moraine
drumlins, eskers, kettles, outwash plain