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

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

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

Agents of Mechanical Weathering Ice Wedging Abrasion Gravity Organic Activity

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)

Agents of Chemical Weathering Carbonation Oxidation Acid Precipitation Plant Acid

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?

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

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

Agents of Erosion: Wind Rain Ice Snow Agents of Erosion

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

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

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

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

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

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

Properties of Soil

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.

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

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

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

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

Soil Formation Topsoil Subsoil Partially weathered bedrock Bedrock

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?

Soil Formation- Weathering Physical breakdown Frost wedging

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

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?

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

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.

Karst Topography

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

Swift Cave in Yunnan, China

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

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

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

Permeability

Permeability

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

Permeability When the pores spaces are connected the permeability is greater

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

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

Groundwater Features Permeable layers Impermeable Layers

B E L L W O R K

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

Groundwater Features Which wells would be successful?

Bell Work Name each layer using your notes:

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?

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

Freshwater Supply Earth’s fresh water supply is finite.

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

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!

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

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?)

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

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?

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 http://vimeo.com/9887737

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.

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

Watersheds in VA

Chesapeake Bay Watershed What happens here… affects us here.

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

Chesapeake Bay Impact Crater

Chesapeake Bay Impact Crater

Chesapeake Bay Impact Crater

Chesapeake Bay Impact Crater http://www.liveleak.com/view?i=348_1385144076

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

Our Watershed Read and respond- Chesapeake Bay

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