1. Weathering, Erosion, Soil, Freshwater, & Karst Topography
Unit 7-1 and 7-2

2. Weathering
Weathering – the process by which rock materials are broken down by the action of mechanical (physical) and chemical processes.
Two types:
Mechanical (Physical) Weathering
Chemical Weathering

3. Mechanical Weathering
Mechanical Weathering – rocks are broken down into smaller pieces by physical means.
This can be done by:
Ice Abrasion
Wind Water
Gravity Temperature
Plants Animals

4. Agents of Mechanical Weathering
Ice Wedging
Abrasion
Gravity
Organic Activity

5. Chemical Weathering
Chemical Weathering – rocks are broken down as a result of chemical reactions.
This can be done by:
Acidic Water
Acid Precipitation
Acids in groundwater
Acids in living things
Air (SO2 and CO2)

6. Agents of Chemical Weathering
Carbonation
Oxidation
Acid
Precipitation
Plant
Acid

7. Rates of Weathering
Which type of weathering is most likely in cold temperatures?
Which type of weathering is most likely in warmer temperatures?
Which type of weathering is most likely in areas of greater amounts of rainfall?

8. Rates of Weathering 4 3 2 1 1. Tropical rainforest 2. Hot desert
3. Temperate mountains 4. Polar Regions

9. Agents of Erosion:
Erosion – when smaller pieces of rocks are washed, blown or carried away (think TRANSPORTED or MOVED)
Example:
Rivers
Wind
Ice

10. Agents of Erosion:
Wind
Rain
Ice
Snow
Agents of Erosion

11. Deposition
Deposition – the process in which material that has been weathered and transported by erosion is laid down.

12. Soil What is soil? Where does it come from?
Are there different types of soil?
How do they differ?

13. Properties of Soil
Soil Texture – the soil quality that is based on the proportions of the soil particles (the size of the particles)
Sand
Less than 2mm
More than 0.05mm
Silt
Clay

14. Properties of Soil
Soil Texture – the soil quality that is based on the proportions of the soil particles (the size of the particles)
Sand
Silt
Less than 0.05mm
More than 0.002mm
Clay

15. Properties of Soil
Soil Texture – the soil quality that is based on the proportions of the soil particles (the size of the particles)
Sand
Silt
Clay
Less than 0.002mm

18. Properties of Soil Soil Structure – the arrangement of soil particles
Soil Fertility – refers to the “health” of the soil
Humus – the dark, organic material formed in the soil from the decayed remains of plants and animals
The more humus, the healthier the soil generally speaking

19. Properties of Soil

20. Soil Formation
Soil is formed from the weathering of rocks and organic activity
Composed of loose rock fragments and clay derived from weathered rock mixed with organic material.

21. Soil Formation Layer 1: Topsoil (O & A Horizons)
Most biological activity occurs here
Forms a dark layer of organic matter called humus
Decayed plants and animals replenish the soil and add nutrients
Lots of weathering and erosion

22. Soil Formation Layer 2: Subsoil (B Horizon)
Mixture of sand, silt, and clay
Lacks the organic humus found in topsoil

23. Soil Formation Layer 3: Partially weathered bedrock (C Horizon)
Less exposure to the elements
Not as weathered as layers closer to the surface
Little to no organic matter

24. Soil Formation Layer 4: Bedrock (R Horizon) Unweathered solid rock
Parent rock
Base of soil profile
Little to no organic matter

25. Soil Formation
Topsoil
Subsoil
Partially weathered bedrock
Bedrock

26. Practice
Which layer of the soil profile is the most affected by weathering and erosion?
What are four agents of erosion that contribute to soil formation?

27. Soil Formation- Weathering
Physical breakdown
Frost wedging

28. Soil Formation- Weathering
Which layer is experiencing the most biological activity?

29. Karst Topography Karst topography forms where the bedrock is carbonate
Think back to our Minerals unit…
What are some minerals in the carbonate family?
What happens to these minerals when the come in contact with acidic water?
What features do you think form in carbonate bedrock?

30. Karst Topography
Regions where the terrain has been dissolved by physical and chemical weathering

31. Karst Topography
Karst topography is developed in areas underlain by carbonate rocks, including limestone and dolomite.
Karst topography includes features like caves and sinkholes and forms when limestone is slowly dissolved away by slightly acidic groundwater.

32. Karst Topography

33. Karst Topography
Where limestone is abundant in the Valley and Ridge province of Virginia, karst topography is common.

35. Swift Cave in Yunnan, China

36. Sea caves and stalactites in limestone karst terrain, Langkawi Island, Malaysia.

37. This house in northern Lithuania collapsed suddenly due to dissolution of gypsum bedrock.

38. Permeability
Permeability is a measure of the ability of a rock or sediment to transmit water or other liquids.
Water does not pass through impermeable materials.
A substantial amount of water is stored in permeable layers of soil and rock underground.
Water stored in reservoirs underground are called aquifers

39. Permeability

40. Permeability

41. Permeability
Porosity is the amount of empty spaces between sediment grains
Well sorted sediment has more pore space than poorly sorted sediment

42. Permeability
When the pores spaces are connected the permeability is greater

43. Groundwater Features
The water table is the level below which the ground is saturated
Unsaturated layer containing both water and air between grains
Saturated layer containing
water between grains

44. Groundwater Features
Drop in water table level due to pumping from a well

45. Groundwater Features
Permeable
layers
Impermeable
Layers

46. B E L L W O R K

47. Groundwater Features Water table
Which layer(s) would be permeable? Impermeable?
Where is the top of the water table?
Water table

48. Groundwater Features
Which wells would be successful?

49. Bell Work
Name each layer using your notes:

50. Water Cycle Draw a simple diagram of the water cycle.
What did you include?
Are there any other ways water moves through Earth’s systems?

51. Water Cycle
Water is continuously being passed through the hydrologic cycle. Fresh water is necessary for survival and most human activities.

53. Freshwater Supply
Earth’s fresh water supply is finite.

54. Freshwater Supply
Geological processes, such as erosion, and human activities, such as waste disposal, can pollute water supplies.
Volcanic activity
Sedimentation
Acid rain
Runoff
Farming

55. Freshwater Supply Freshwater sources:
Rivers, streams, tributaries
Lakes
Aquifers
Precipitation
99.7% of Earth’s water is in oceans, seas, ice, and the atmosphere
Only 3% is freshwater
Most freshwater is in ice caps
Only 0.3% is available as a freshwater source!

56. Bell Work What does each number, 1-3, represent in the diagram?
What type rock are the sedimentary layers made up of?

57. Freshwater
After you read your article, write a brief summary answer the questions:
Who? (Who does the article address? Who is effected by this issue?)
What? (What is the issue?)
When? (When is the issue occurring?)
Where? (Where is the issue a concern?)
Why? (Why is this issue a concern?)

58. QUIZ! Complete the freshwater quiz together
You may work as a group but each student is responsible for their own work
Quiz is timed!

59. Freshwater is finite
How does this fact impact the way humans use water?
What laws do you think should be put in place to help control the usage of water?

60. Watershed What is a watershed? Do you live in a watershed?
A watershed is an area of land in which all water flows to the same place
Do you live in a watershed?
Yes! We live in the James River Watershed, which is part of the Chesapeake Bay Watershed

61. Major Watersheds in VA
The three major regional watershed systems in Virginia lead to the Chesapeake Bay, the North Carolina sounds, and the Gulf of Mexico.

62. Major Watersheds in VA Chesapeake Bay Watershed
Gulf of Mexico Watershed
North Carolina Sounds Watershed

63. Watersheds in VA

64. Chesapeake Bay Watershed
What happens here…
affects us here.

65. Watersheds How do we determine the boundaries of a watershed?
Watersheds are separated by divides
What does this line represent?
Ridge of the Rocky Mountains

66. Chesapeake Bay Impact Crater

67. Chesapeake Bay Impact Crater

68. Chesapeake Bay Impact Crater

69. Chesapeake Bay Impact Crater

70. Chesapeake Bay Impact Crater
How might the impact crater affect groundwater?
Fractures in the ground allow sea water to move into regions of fresh groundwater
This process is called saltwater intrusion

71. Our Watershed
Read and respond- Chesapeake Bay

72. Major Features of Tectonic Boundaries
Bell Work
Take out your study guide.
Copy the table below.
Use the word bank to complete the table comparing two of the tectonic boundary types.
Major Features of Tectonic Boundaries
Convergent
Divergent
Zones
Physical Features
Word Bank
Spreading fault or continental rift
Faulted mountains and volcanoes
Collision and subduction
Mid-ocean ridges and volcanoes