The document discusses several key factors that control landform development: 1) Geomorphic agents and processes such as weathering, erosion, and sediment transport affect how rocks and sediment are shaped over time. 2) The types of surficial materials present influences landform evolution. 3) The tectonic setting determines what rock materials are exposed and how they are distributed across the surface. 4) Climate determines the active geologic agents and affects the rates of physical and chemical weathering.

1. Controlling Factors
Geomorphic Agents and Processes: Affect how rocks and sediment
are eroded and transported.
Surficial Materials: Rocks and sediment of different types are
located at the earth’s surface.
Tectonic Setting: Determines what materials are exposed at the
earth’s surface and the manner in which they are distributed.
Climate: Determines what geologic agents are available to interact
with exposed rock materials and influences the rate of physical and
chemical reactions.

2. Climate
Determines what geologic agents are available to interact with exposed rock materials.
Influences the rate of physical and chemical reactions.

3. • Combination of atmosphere and hydrosphere.
• Driven by the Sun and modified by the earth’s rotation.
• Responsible for storms, rivers, lakes, groundwater, sand dunes, glaciers, beaches, soil formation,
oceanic currents, global circulation patterns, climatic belts, and anything thing else involving water or
air.
• Whereas, the tectonic system builds things up, the hydrologic system wears them down.
• Primary processes include weathering, erosion, sediment transport, deposition, and lithification
Hydrologic System
From Okanagan University College, Department of Geography website

4. Photo by NASA

5. States of Matter
Matter exists in three forms (states) - solid, liquid, and gas. These represent the ability of
atoms to vibrate and move about. The two primary controls are temperature and pressure. An
increase in temperature adds energy, causing atoms to vibrate and move further apart,
decreasing density. An increase in pressure forces atoms closer together, decreasing their
ability to vibrate and increasing density.
Atoms are loosely packed and the
substance conforms to the shape of its
container.
Atoms are closely packed and the
substance maintains its own shape.
From Hamblin & Christiansen (2001)
Atoms arecompletely separated
and expand to fill all available
space.

6. Energy Transfer
Most energy is transferred from one substance to another through three processes -
conduction, convection, and radiation. This transfer can often be measured by
changes in temperature.
Conduction: Energy is transferred by direct contact as the
vibration of atoms on the surface of one material is transmitted
to those on the surface of a neighboring material.
Convection: Energy is transferred as material moves from place to
place due to differences in density, caused mostly by contrasts in
temperature. When a material is heated, the atoms move farther apart,
density decreases, and it rises. When the material is cooled, atoms move
closer together, density increases, and it sinks.
Radiation: Energy is transferred through space by electromagnetic
waves.

7. Global Water Distribution
Lakes, streams, ground water, and atmospheric water = 0.65%
Oceans = 97.2%
Photo by W. W. Little
Ice = 2.15%
Photo by Global Marine Drilling
Photo by W. W. Little Photo by W. W. Little Photo by W. W. LittlePhoto by W. W. Little

8. The Sun
The Sun is the energy source driving the hydrologic system. Without
the Sun, there is no hydrologic system.
Photo by NASA

9. Earth’s present
atmosphere is distinctly
different from that of its
nearest neighbors, Venus
and Mars; although, it is
believed that earth’s early
atmosphere was similar
to that of its neighbors.
Atmospheric Compositions

10. Because of gravitational attraction, most of earth’s atmosphere is
concentrated near the surface in the troposphere, causing both
temperature and pressure to be higher at lower altitudes.
Atmospheric Pressure & Temperature

11. Climatic Belts & Temperature
Earth’s surface temperature is greatest at the equator, decreasing to a
minimum at the poles.

12. Climatic Belts & Precipitation
The amount of precipitation that falls is strongly tied to latitude. It is
highest at the equator, very low just north and south of the equator,
moderate in mid-latitude regions, and lowest at the poles.

13. Because of earth’s spheroidal shape, a given amount of solar energy is
spread over a larger area at the poles than along the equator.
Temperature and the Sun

14. Coriollis Effect
Earth’s rotation causes an atmospheric deflection that is clockwise in the
northern hemisphere and counterclockwise in the southern hemisphere.
This creates distinct belts of atmospheric circulation.

15. Surface Runoff
Stream channels are the most pervasive surface characteristic of
earth’s continental masses. They are to earth what craters are to
the moon.
Photo by NASA

16. Streams carry both water and sediment (boulders to dissolved ions) from
the land to the sea, where the sediment is ultimately deposited.
Photo by W. K. Hamblin
Stream Deposition (deltas)

17. • Intensity and duration of rainfall.
• Prior moisture content of surface material.
• Porosity and permeability of surface material.
• Gradient
• Amount and type of vegetation.
• Temperature
Runoff Controls

18. Surface runoff can be temporarily impounded by lakes and reservoirs.
Photo by W. K Hamblin
Lakes and Reservoirs

19. Glaciers represent a
temporary disruption of
normal surface runoff.
Water is tied up in ice,
which flows downhill in
much the same manner
as rivers but much more
slowly.
Glaciers

20. Deserts
Deserts represent a disruption of the river system, which occurs when temperatures are
sufficiently high so that the hydrologic system is partially shutoff due to a lack of
precipitation. Eolian (wind) processes dominate and river systems can be completely
overwhelmed by dune fields.
Photo by W. W. Little

21. Changing Environments
Radar images taken through dune fields of the Sahara Desert by the
Space Shuttle reveal a well-developed drainage system.
Photos by NASA

22. Groundwater System
Some precipitation seeps into the
ground and flows through the
subsurface. It can return to the
surface through seeps and springs
or flow directly into streams,
lakes, or the sea.

23. Groundwater dissolves rock and produces karst (dissolved)
features, including sink holes and caves.
Karst Topography
Photo by W. W. Little

24. Landslides are typically caused by a high moisture content in
surficial materials.
Landslides

25. • Waves: part of the hydrologic system driven by unequal solar heating
(wind).
• Tides: part of the hydrologic system driven by lunar gravitational
attraction.
• Submarine currents: part of the hydrologic system driven by water
density contrasts (related to chemistry amd temperature) and earth’s
rotation.
Shoreline Systems
Rocks are eroded and sediment is transported along shorelines by
waves, tides, and submarine currents.
Photo by W. W. Little

26. Seawater is mostly cold, but
above freezing. However, a
thin layer of warmer water
exists at the surface, where it is
heated by solar radiation. This
is particularly evident at the
equator.
Temperature of Seawater

27. As a result of the Coriollis Effect, ocean surface currents rotate
clockwise in the northern hemisphere and counterclockwise in the
southern hemisphere. These currents have important climatic
implications.
Oceanic Surface Currents

28. Due to the Coriollis Effect,
warm equatorial surface water is
transported northward along the
U.S. eastern coast and across the
Atlantic Ocean toward Europe,
affecting climatic conditions on
both sides of the Atlantic.
Gulf Stream

29. Cold, highly saline polar water sinks and moves along the
seafloor, then slowly moves upward where it mixes with warmer
water of mid and low latitudes.
Deep Ocean Circulation

30. Oceanic circulation is very slow but over time involves mixing of
the entire volume of the sea.
Whole Ocean Circulation

31. Controlling Factors
Geomorphic Agents and Processes: Affect how rocks and sediment
are eroded and transported.
Surficial Materials: Rocks and sediment of different types are
located at the earth’s surface.
Tectonic Setting: Determines what materials are exposed at the
earth’s surface and the manner in which they are distributed.
Climate: Determines what geologic agents are available to interact
with exposed rock materials and influences the rate of physical and
chemical reactions.

32. Geomorphic Agents and Processes
• Atmospheric moisture (weathering)
• Gravity (mass movement)
• Running water (stream erosion, transport & deposition)
• Groundwater (dissolution & precipitation)
• Flowing ice (glacial erosion, transport & deposition)
• Wind (eolian erosion, transport & deposition)
• Waves (long-shore erosion, transport & deposition)
• Tides (tidal erosion, transport & deposition)
Determine how the land is sculpted

33. Atmospheric Moisture
The amount of moisture in the air and its composition will control the
type and degree of chemical weathering affecting material surfaces.

34. Gravity
Material loosened by
weathering tends to be
pulled down hill by
gravity.

35. Running Water
Rivers can be thought of as conveyor belts that remove weathered
materials and transport them to a depositional basin.

36. Groundwater
Groundwater can dissolve or precipitate minerals dependent upon
temperature and pressure conditions, composition of the material
through which the water is flowing, and the type and concentration of
dissolved ions in solution.

37. Flowing Ice
Flowing ice represents a modification of surface runoff due to
extremely cold temperatures. Glaciers are highly competent as an
erosional agent and sediment transport mechanism and produce many
distinctive landforms.

38. • Snow accumulates more rapidly than it melts.
• As snow reaches a sufficient thickness, it compresses to ice and begins to flow.
• Flowing ice scours the underlying bedrock producing a cirque.
• As the glacier grows, it extends further down the valley.
• Ultimately, a landscape of U-shaped and hanging valleys, horns, aretes, and other features is
produced.
Alpine Glacial Valleys

39. Wind
Deserts represent a disruption of surface runoff due to a lack of
precipitation. Wind is the least competent mechanism of sediment
erosion and transport but is still responsible for the formation of many
landforms.

40. Waves
Waves move sediment along the coast by means of longshore currents.
They erode at headlands and deposit in bays, causing a smoothing and
straightening of the shoreline.

41. Tides
Tides move sediment back and forth perpendicular to the coastline.
They produce flat depositional surfaces characterized by rippled plains,
marshes, and channels with irregular patterns.

42. Controlling Factors
Geomorphic Agents and Processes: Affect how rocks and sediment
are eroded and transported.
Surficial Materials: Rocks and sediment of different types are
located at the earth’s surface.
Tectonic Setting: Determines what materials are exposed at the
earth’s surface and the manner in which they are distributed.
Climate: Determines what geologic agents are available to interact
with exposed rock materials and influences the rate of physical and
chemical reactions.

43. Surficial Materials
Geomorphic features are strongly influenced
by the nature of materials exposed at the
surface.
• Bedrock or sediment
• Composition
• Stratigraphy

44. Landscape Evolution
Landscapes evolve toward an equilibrium that reflects a balance
between tectonic and hydrologic forces. When changes occur in one of
these systems, the landscape adjusts to reflect those changes.

46. The Great Unconformity
Arizona Missouri
Southeastern
Canada

48. Concepts of Equilibrium
Equilibrium means balance. In geomorphology, it refers to no net
change, usually in terms of a balance between deposition and
erosion, uplift and downcutting, or soil production and removal.
• Equilibrium is strived for but seldom achieved.
• A change in one part of a system affects all others.

49. Fluvial Equilibrium
Recent uplift in excess of erosional rates
results in a system that is out of
equilibrium.
Weathering and erosion dominate
headland areas with removed material
being transported to a depositional basin.
As headlands recede, both erosional and
depositional rates decrease.
If the region remains stable for an
extended period, equilibrium, where
erosional and depositional rates are equal,
might be achieved.

50. • Sea level is the ultimate base level
• Lakes and reservoirs provide temporary base levels
• Changes in sea level can be eustatic or relative
• Changes in base level create and destroy accommodation space
Base Level
Base level is the level below which erosion cannot occur and above
which deposition does not take place.

51. Graded (Longitudinal) Profile
Stream gradient is related to water velocity and the load it can transport.
A change in any of these affects the other two. Each can be influenced
by factors outside of the stream system, such as base level fluctuations
(gradient), precipitation changes (discharge), and sediment character.

55. Coastal Equilibrium (Channel Mouths)
Deltas represent a “battle” between fluvial and marine (wave & tidal) processes.
Delta morphologies are highly influenced by which of these processes dominates.

56. Coastal Equilibrium (headlands & bays)
Coastal processes work to straighten and smooth shorelines by focusing
energy at headlands, with minimal energy within bays. Overall basin
size and geometry, composition of coastal materials, and wind
characteristics all play a role.

57. An open system is one in which both energy and matter cross its
boundaries. A closed system allows only energy to enter or exit.
Open vs. Closed Systems
Open System Closed (nearly) System

58. Negative Feedback Systems
Negative feedback systems adjust internally to external forces.

59. Positive Feedback Systems
Positive feedback systems feed upon and ultimately eliminate
themselves. External forces enhance (accelerate) internal processes.

60. System Complexity
Geological systems can be highly complex, with numerous
interdependent variables, making modeling extremely difficult.