Plate tectonics

Scales of relief
Relief:  vertical elevation differences in landscape

Orders of relief

First order relief features

continents
ocean basins

Second order relief features

continental

alpine chains
continental shields
continental shelves

ocean basins

basin floor
mid-oceanic ridges
continental rises
ocean trenches

Third order relief features

landform complexes
individual landforms
individual features

Continental drift: explaining 2nd order relief features

Historical observations

Evidence

shapes

rocks

fossils

glaciation

Plate Boundaries

Diverging (spreading)

Converging

Ocean-continent

Ocean-ocean

Continent-continent

Arc-Continent

Transform

Forces placed on rocks

Stress
Strain

elastic deformation
plastic deformation
rupture

Describing tilted rocks and faults
Tilted rocks
 
dip
strike
Faults
fault plane
fault line
fault scarp

Dip-slip faults
Normal Faults
Horst and Graben
Revere Fault
Overthrust fault
Strike-slip faults
Oblique-slip

monocline
anticline
syncline
overturned fold

Black Hills, SD (Dome)

Volcanic landforms

Shield volcanoes

Where?
Form
Composition
Process
Types of lava

Pahoehoe
Aa lava

Where formed
Hot spots
How a shield forms

Where
Structure

Where
Form
Composition
Process
Caldera

Weathering and Karst topography

Types of erosion

Physical Weathering

mechanical
physical break-up of rock
minerals not altered
cold climates

Chemical weathering

chemical alteration
change of minerals
water
warm-wet climates

Physical Weathering

Frost Action

Repeated freezing and thawing
Expansion and fracture

Crystallization

Salt crystal growth
Expansion and fracture

Temperature expansion/contraction

Heating and cooling of rocks

Unloading

Rocks form under great pressure
After exposure
Spalling
Exfoliation
Spheroidal weathering

Plants

Root pry

Oxidation

Dissolved oxygen reacts with Fe, Al, etc.
Above water table
Iron oxide (red) and aluminum oxide (yellow)

Carbonation

CO₂ reacts with water
Weak acid
CO₂ + H₂O ? H₂CO₃ (carbonic acid)
Susceptible rocks

Chelation

Organic acids
Mosses and lichens
Helps in soil formation

Hydrolysis

Minerals combine with water
Silicate minerals
Weak acid is formed

Highly weathered limestone
Carbonation
Features

surface pits and bumps
poor drainage
caves/caverns

Cave features

Sinkhole (doline)
Sinkhole
Uvalas
Tower karst
Stalactites
Stalagmites
Column
Curtain
Flowstone
 
 
 

Studying hillslopes

Why study hillslopes?
Inappropriate use of hillslopes
First, weathering
Then, mass movement
 

erosion
mass movement

Rainsplash
capped columns
Rainwash
infiltration capacity
rainfall intensity

Drawn by gravity
Fast or slow, large or small
Mechanisms of slope stability
Forces acting on slope

Rockfall
Rapid freefall
Tallus slope
Landslide
Fracture on a planar surface
Rapid or slow
Two types
slide
rotational slump
Flow
Behaves like plastic
Types
debrisflow
earthflow
mudflow
Lahar (type of mudflow)
Creep
Slow movement
Freeze-thaw
Solifluction
Polar and high mountains
Active layer

Factors affecting slope stability

Soil water
Undercutting
Earthquakes
 
 

Fluvial Processes and landforms

Running water

Two processes

overland flow
streamflow

Deposition

Alluvium

Erosion (overland to streamflow)

Splash erosion - Sheet erosion - Rill erosion - Gully erosion - Streamflow
Erosion by streamflow
Increased ability
Three mechanisms

hydraulic action
abrasive tools
chemical action

Transportation

Quantity of stream load
Competence
Capacity
Processes of transportation

solution
suspended load
traction
saltation

What’s eroded up, must be deposited
Decrease in velocity
where, why?
Alluvium

Factors affecting velocity
hydraulic radius (R)
slope gradient (S)
roughness (n)
Looks can be deceiving

Laminar flow
low velocity
smooth surfaces
far from channel

high velocity
rough surfaces
channel contact

Straight
Meandering
Braided

Drainage Basins
Types of drainage basins
Drainage basins
Drainage density

Describing watersheds

Stream order
Numerical patterns

Depth and width
Sediment
Discharge
Floods

Concave
Channel equilibrium

aggrading
degrading
graded

Lateral migration

Valley

Downcutting
Base level
Rejuvenation
uplift
drop in base level
increase in discharge
decrease in sediment load

Base Level
Valley develoment
Downcutting
Base level
Rejuvenation
uplift
drop in base level
increase in discharge
decrease in sediment load

Floodplains

Lateral planation
Undercuts valley wall
Cut bank
Point bar
Course vs. fine sediments
Levees
Levees

Terraces

Downcutting followed by aggradation
Alluvial terraces

Oxbow lakes

Active meanders
Gooseneck curves
Meander cutoffs
Oxbow lake
Meander scar
“Billabong”

Deltas

Streams flow into lakes, oceans
Velocity slows
Distributaries
Birdfoot delta
Change over time (Miss. R.)

Alluvial fans

Glacial processes and landforms

Introduction

Where?
How many?
The past
why ice ages
Types of glaciers
continental
alpine (mountain)

Past extent
Shaping of topography
Ice caps
Ice fields
Nunatak
Where
Greenland
Antarctica

Most common
Size?
Where?
Types
cirque glacier
valley glacier
piedmont glacier
Further classification
Temperate (warm) glacier
Polar (cold) glacier

Stages
Névé
Firn

Glacial movement
Internal deformation
Basal slipping

Erosion
scouring
plucking
roche moutonnée
Deposition
till
moraine
outwash plain
kame
esker
kettle lake
drumlin

In mountain:
cirque
arête
horn
col
In the valley
glacial trough
hanging valley
tarn
paternoster lake
fjord