1. Chapter 5: Section 1 Surface Processes and Landscapes
Earth Science
Chapter 5: Section 1
Surface Processes and Landscapes

2. Water and the Ground
The continuous movement of water between the atmosphere and the ground is called the water cycle.
Evaporation – changing liquid to gas
Transpiration – process plants release water into the atmosphere
Evapotranspiration – all the water released into the atmosphere by both evaporation and transpiration.

3. Water and the Ground Once on Earth’s surface water can:
Flow along the surface as runoff
Sink into the ground (infiltration) and become part of the ground water supply
Remain on the surface as snow or ice
Evapotranspire back into the atmosphere again

5. Water and the Ground
Most precipitation that reaches the Earth’s surface infiltrates into the ground.
This can only happen if the ground is permeable (allows water to pass through it).
The more saturated the ground, the less infiltration
The steeper the slope, the less infiltration

6. Water and the Ground
Permeability is the ability of the regolith (loose soil on top of bedrock) to allow water to pass through it.
In order for the ground to be permeable, pore spaces within the regolith must be interconnected.
Material that does not allow water to pass through it is said to be impermeable.

7. Water and the Ground
As it rains, water infiltrates the regolith until it reaches an impermeable bedrock layer.
The water cannot infiltrate further, so it fills in the pores above the impermeable layer of bedrock, forming the zone of saturation.
The upper surface of the zone of saturation is called the water table.
The zone above the water table is called the zone of aeration.

9. Water and the Ground
The porosity of a material is the amount of open pore space between particles.
Expressed as a percentage of open space
Dependent upon shape, packing, and sorting.
Rounded particles have greater porosity than angular particles
Loosely packed particles have a greater porosity than tightly packed particles
Sorted particles have a greater porosity than unsorted particles.
Particle size does not affect porosity

11. Water and the Ground Water retained by particles
Particle size of a material does not affect porosity, but it does affect the amount of water retained.
Smaller particles will retain more water than larger particles, because smaller particles have a greater total surface area.

12. Water and the Ground
Capillarity is the ability of water to rise through pore spaces.
Water can move upward through soil, much as water rises from the roots to the limbs of a tree.
In loose materials, the smaller the pore size, the greater the capillarity.

13. Water and the Ground
Runoff occurs when rain falls faster than it can seep into the ground
The factors that will increase runoff are:
Saturated pore spaces in the ground
Steep slopes
Little vegetation
Impermeable surfaces
Most runoff is carried into streams and ends up in the ocean.

14. Weathering Weathering vs. erosion
Weathering is the chemical and physical breakdown of rocks
Weathering is a preparation for erosion
Erosion is the movement of weathered materials from one place to another
The two general types of weathering are chemical and physical.

15. Weathering
Physical weathering occurs when rock is cracked, split or broken into sediments.
Types of physical weathering:
Frost action – breakup of rocks caused by alternate freezing and thawing of water.
Abrasion – wearing down of rocks as they rub or bounce against each other.
Exfoliation – the peeling away of large sheets of loosened material.
Plant and animal action – roots grow in cracks of rocks or animals burrow through soil and rock

21. Weathering
Chemical weathering occurs when rock is broken down by chemical action resulting in the change in composition of the rock.
Oxidation - O2 chemically unites with minerals
Hydration - H2O chemically unites with minerals
Carbonation – dissolved CO2 in water forms carbonic acid & dissolves limestone
Organic Decay – acids from dead plants dissolve in water, then the water solution dissolves rocks

25. Weathering Climate and Weathering
Physical weathering is more pronounced in moist, cold climates where alternate freezing and thawing occur.
Chemical weathering is more intense in warm, moist climates.
Usually, the more moisture available, the more weathering occurs.

26. Weathering Weathering rates depend on 3 variables
Particle size and surface area
Larger, solid particles of rock weather more slowly than do smaller, loose pieces
Mineral composition
Harder rocks weather slower than soft rocks
Climate
Humid climates have more weathering than dry climates

27. Soils
Soil is the part of the weathered regolith in which rooted plants will grow.
Major product of weathering
Composed primarily of particles of rocks, minerals, and organic matter.
Contains solids, liquids, and gasses

28. Soils
As soils mature, they grow richer, developing a series of layers called a soil profile.

29. Erosion
Erosion is the transportation of loose sediments or rocks produced by weathering.
Residual sediment is rock that has remained in the place it has been weathered.
Transported sediment is rock that has been moved from its place of origin to another location.
Transported sediment is far more common.

30. Erosion The major agents (forces) of erosion are: Gravity
Running water
Glaciers
Wind
Waves

31. Erosion Gravity Primary driving force behind all erosional systems
When acting with another erosional agent gravity provides the kinetic energy necessary to transport sediments
Gravity acting alone, like pulling rock down a steep cliff or slope, usually results in angular rocks

32. Erosion Running Water Primary agent of erosion on Earth
Sediments carried by water are usually smooth and rounded due to abrasion.
Valleys carved by streams are V-shaped.
Most running water is found in streams or rivers.
A direct relationship exists between the volume of water in the stream (stream discharge) and/or gradient and stream velocity.

33. Erosion
The stream velocity is generally greatest just below the surface near the center of the channel.
greatest velocity

34. Erosion
Water near the outside of a curve has a greater velocity than water near the inside of a curve.
Erosion takes place at the outside of the curve and deposition occurs at the inside.

35. Erosion
The size of particles a stream can carry increases as the stream velocity increases
Streams can carry sediments in 3 ways
Dissolved particles in a solution
Fine sediments in suspension
Larger rocks bounced, pushed, or rolled along the stream bed (saltation).

36. Erosion Glaciers Most of NYS has evidence of glacial erosion
Valleys carved by glaciers are U-shaped.
Rocks are unsorted, angular and may have parallel scratches or one polished side.
Like with running water, the greater the volume of ice and/or the steeper the slope, the greater the velocity and the more the glacier erodes.
Can transport the largest particles

37. Erosion
Wind
Sediments are usually angular and, although smooth, not as smooth as by running water.
Rocks are often pitted and frosted.
Like with running water and glaciers, the greater velocity the larger the particles the wind can carry.

38. Deposition
Deposition is the release of sediments from an erosional system.
Caused by the decrease of carrying power of an erosional agent.
Factors Affecting Deposition
Particle size
The settling rate of particles is determined mainly by its particle size

39. Deposition
With all other factors equal, larger particles settle faster than smaller particles because they weigh more.
In running water, very small particles remain suspended for long periods of time.
When a mixture of sediment sizes settle in still water sorting in horizontal layers takes place.

41. Deposition Particle shape
If all other factors are equal, smooth, spherical objects usually settle faster than angular, flatter particles.
Particle Density
If particles are about the same size and shape, higher-density particles will settle faster than lower-density particles.

42. Deposition Velocity of Transporting Medium
As the velocity decreases, there is a loss of carrying power and larger, heavier, denser particles settle out first.
Horizontal Sorting

43. Deposition Glacial deposition Two main types are till and outwash.
Till is unsorted rock material deposited directly from glaciers.
Outwash is rock deposited by the meltwater of a glacier and can show horizontal sorting.

44. Erosional-Depositional System
An erosional-depositional system combines the erosional processes, the transporting agents and processes of deposition.
Examples:

46. Erosional-Depositional System