UNIT 4: AGENTS OF EROSION
UNIT BIG IDEA/ESSENTIAL QUESTIONS
Water and wind are active agents of erosion that
constantly reshapes the earth’s surface.
 Essential Questions

How does porosity, permeability, aquitards, and
aquifers influence groundwater?
 What conditions would create karst topography?
 What importance does deltas have?
 How can glaciation erode, alter, and reshape the
earth’s surface?

ES Standards: 3.1, 3.4, 3.5
KEY VOCABULARY
Alluvial fan
 Delta
 Drainage basin
 Infiltration
 Karst topography
 Meander
 Natural levee
 Oxbow lake
 Permeability
 Porosity

Alpine glacier
 Arete
 Cirque
 Deflation
 Drumlin
 Moraine (lateral, medial)
 Till
 Zone of accumulation
 Zone of wastage

RECAP
 Weathering-process
that breaks
downs materials (chemical and/or
mechanically) at the earth’s surface.
 Erosion- removes weathered
material by wind and water.
 Deposition- deposits eroded material
in a new location making new
features
QUESTION OF THE DAY
What
is the
hydrological cycle?
WATER
Infiltration depends on
 Intensity/duration of rainfall
 Prior wetted condition of soil
 Soil texture
 Slope of the land
 Nature of vegetative cover
 What is a Drainage Basin?
 River Systems
 3 parts: zone of erosion, zone of sediment
transport, zone of sediment deposition

STREAMFLOW
 Laminar
or Turbulent
 Which type of flow is responsible for
whitewater rapids?
 Stream Velocity is based upon
 Gradient
 Shape, size, and roughness of channel
 Discharge
Width x depth x velocity
TRANSPORTATION OF ERODED MATERIAL
 Dissolved
load, Suspended Load, Bed Load
 Competence determines the maximum size
of particles that can be carried
 Capacity is based upon a streams
discharge
 Stream Channels
 Bedrock
 Alluvial
 Meanders, Oxbow Lakes, Cut banks and
Point bars
 Stream Valleys
DEPOSITIONAL FEATURES
Floodplains
 Delta
 Levees
 Alluvial Fans

QUESTION OF THE DAY
What
are some ways to
control flooding?
GROUNDWATER
 Rate
of movement and amount
depends on
 Porosity
 Permeability
 Aquitards
 Aquifers
GLACIATION
Two types
 Glacial Movement

Zone of accumulation
 Zone of wastage


Erosion by plucking and abrasion
GLACIAL FEATURES VIA EROSION
Glacial Trough
 Hanging Valleys
 Cirques
 Aretes
 Horns
 Fjords

DEPOSITIONAL FEATURES
Till vs. Stratified Drift
 Glacial Erratics
 Moranines
 Outwash Plains
 Drumlins
 Eskers
 Kames
 Kettle Lakes

CAUSES OF GLACIATION
Plate Tectonics
 Changes in Earth’s Orbit
 Changes in output energy from Sun
 Albedo and Atmosphere composition

WIND EROSION AND DEPOSITION
Deflations and Abrasion
 Loess
 Sand Dunes
