THE SCIENCE OF MAPS 8.9C interpret topographic maps and satellite views to identify land and erosional features and predict how these features may be reshaped by weathering ATL Skill: Critical thinking - Use models and simulations to explore complex systems and issues
TODAY S FOCUS: Review weathering, erosion and deposition briefly Interpret satellite views to identify land and erosional features Predict how land features in topographic maps and satellite views may be reshaped by weathering, erosion and deposition.
WEATHERING, EROSION AND DEPOSITION Let s Review!
WEATHERING DEFINITION Weathering is the process of breaking down rocks into smaller pieces
WEATHERING 2 TYPES Chemical Weathering Examples: Carbonation such as in cave formation Oxidation such as iron turning red and copper turning green Plant acid breakdown of soil and rock Acid rain dissolving statues
CHEMICAL WEATHERING Caves are formed by the dissolution of limestone. Rainwater picks up carbon dioxide from the air and as it percolates through the soil, which turns into a weak acid. This slowly dissolves out the limestone along the joints, bedding planes and fractures, some of which become enlarged enough to form caves
CHEMICAL WEATHERING Oxidation such as iron turning red and copper turning green
CHEMICAL WEATHERING Plant acid breakdown of soil and rock Acid rain dissolving statues
WEATHERING MECHANICAL WEATHERING Examples: Abrasion by sand and other rock particles Roots from trees or other plants forcing cracks apart Ice Wedging from water freezing and expanding in cracks such as potholes on the street Exfoliation from extreme high temperatures causing rock to crack and flake off like an onion Animal actions such as burrowing loosening the ground
MECHANICAL WEATHERING 1. Abrasion by sand and other rock particles 2. Roots from trees or other plants forcing cracks apart 3. Ice Wedging from water freezing and expanding in cracks such as potholes on the street 1 2 3
MECHANICAL WEATHERING 1. Exfoliation from extreme high temperatures causing rock to crack and flake off like an onion (thermal expansion) 2. Animal actions such as burrowing loosening the ground 1 2
EROSION DEFINITION Erosion is the process that moves rock, sediment and soil from one place to another
EROSION Agents of Erosion these are the forces that cause erosion Moving water such as rain water, streams, rivers, and beach erosion Wind such as dust storms and general blowing of sediments Gravity such as what causes landslides and mudslides Glaciers/Ice - sliding erodes the rock surface underlying a glacier. Meltwater freezes in cracks, and pieces of bedrock are pried loose and incorporated into the ice (similar to frost wedging). These new pieces of rock grind against each other and the bedrock underneath.
EROSION 1. Moving water carries the sediment 2. Wind carries sediment and causes abrasion 1 2
EROSION CAN BE SEEN ON SATELLITE IMAGES:
DEPOSITION DEFINITION Deposition is when rock, sediment and soil settles out of the water or wind that is carrying it, and is deposited in a new location. This is a CONSTRUCTIVE (building) process!
DEPOSITION ALSO CAN BE DETECTED BY COMPARING MAPS! Examples River deltas Meandering rivers, streams Oxbow lake Alluvial fan Sand dunes, new beach sand, sediments on ocean and lake floors
DEPOSITION SHOWN BY IMAGES: River deltas Alluvial fans
DEPOSITION SHOWN BY IMAGES: Sand dunes, new beach sand A sand fence, is used to force windblown, drifting sand to accumulate in a desired place. Sand fences are employed to control erosion, help sand dune stabilization, and to keep sand off roadways
INTERPRET SATELLITE VIEWS TO IDENTIFY LAND AND EROSIONAL FEATURES
HOW DO WE USE IMAGES TO FIND CHANGES? We compare results from historical images and current images
HOW DO WE USE SATELLITE IMAGES TO FIND EROSION? We compare results from different images of the same area. The time period can be relatively short or long.
HOW DO WE USE SATELLITE IMAGES? We compare results from before and after major weather or geological events we can pin-point areas that need to most help, how to send relief efforts, etc. Earthquake in Nepal in 2015
PREDICT HOW LAND FEATURES IN SATELLITE VIEWS MAY BE RESHAPED BY WEATHERING, EROSION AND DEPOSITION
SO HOW DO WE MAKE THESE PREDICTIONS? An example: the island of Haiti in 2002 what do you see?
8 YEARS LATER, IT LOOKS LIKE THIS WHAT HAPPENED? Huge amounts of sediment eroded from the deforested areas. This sediment was also deposited in new locations.
8 YEARS LATER, IT LOOKS LIKE THIS WHAT HAPPENED? Is this type of change predictable?
COASTAL EROSION MONITORING This is becoming more and more important as our climate changes. More than half of the world s population lives in coastal areas. Coastal erosion has become a serious issue for coastal communities and ecosystems around the world. Coastlines are increasingly subject to natural and anthropogenic influences such as global warming related sea level rises and storms and changing land-use patterns e.g. construction, deforestation and agriculture
COASTAL EROSION MONITORING Erosion changes in the Mediterranean
INDEPENDENT PRACTICE: