Welcome Back!! : Welcome Back!! Please make sure you have this week’s homework packet ready!
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What We Will Cover Today!!! : What We Will Cover Today!!! A brief review of Relative Time, absolute Time, and Correlation.
Discuss the difference between Erosion and Weathering.
List some common areas influenced greatly by erosion and some land forms created as a result.
Discuss three main forces of erosion.
Discuss the difference between chemical and physical weathering, plus examples of each.
Geologic Time Review… : Geologic Time Review… Geologic time consists of Relative Time and Absolute Time coupled with Correlation. (Use the three items below to answer Monday #2)
Relative Time: the order in which events happened.
Absolute Time: The exact year or date that things happened.
Correlation: comparing samples of rock layers from more than one location.
It is where we take core samples from more than one location and compare them for similarities, differences, and information on what biological and geological activity occurred in the past. (Monday #1)
Now For The New Stuff…Erosion and Weathering! : Now For The New Stuff…Erosion and Weathering! Weathering: The process of breaking down rocks and rock formations into sediment.
Erosion: The transporting of sediment AND other materials like rocks, plants and dead animal matter from one location to a new one.
(Hey my great students, this is number 1 for Tuesday.)
Types of Erosion Forces : Types of Erosion Forces On our planet there are many ways erosion can occur but there are three main types.
Moving Water
Wind
Glacier Movement
Moving Water : Moving Water Occurs anywhere water is flowing on the Earth’s surface. (Creeks, rivers, springs)
Occurs when rain water or snow melt seeps into the ground.
Occurs on coast lines of lakes, ponds, and oceans.
The faster and more water moving, the larger the sediment pieces and the more sediment amounts that can be carried.
Is the most common, and during many years the most destructive. Each year during spring and periods of heavy rain overrun rivers can carry tons of sediment into homes, streets, and farms which destroy crops, kill livestock, and wash away houses.
Wind : Wind Is the most common, but it is not always as destructive as moving water.
Occurs everywhere.
High wind speeds will carry larger amounts of sediment and larger sediment pieces.
Glaciers-Giant Moving Ice Sheets! : Glaciers-Giant Moving Ice Sheets! Slow moving! Only moves a few feet forward per day, week, month or year as more water freezes and is added to the glacier.
When the glacier melts the running water erodes the land underneath. It looks like the glacier is moving backward, but it is really getting destroyed. If the glacier melts fast enough large lakes can be formed.
Glaciers on the move can carve rock formations, dig deep canyons into the ground, and move huge boulders and incredible amounts of sedimentary materials.
Only occur on high mountains and near the polar regions.
(Thursday # 2)
Common Areas Effected By Erosion : Common Areas Effected By Erosion Areas near moving water like river beds, coastal areas, and flood plains.
Sand dunes and dessert areas.
Mountain passes where glaciers flow down during the winter months.
Anywhere sediment and rocks can be moved easily.
(Tuesday Number 2)
Common Land Features Created By Erosion : Common Land Features Created By Erosion Points and Peninsulas
Waves that pound shorelines will push sand and rocks down shore. Sometimes these materials gather in one location and create a point or peninsula.
This point or peninsula will continue to grow as more of the shoreline above it gets pushed downward, and collects at the point or peninsula to build upon it s shown in this picture.
Tawas point shown here is two hours north of here off US-23 on Lake Huron. It is both a state park and campground!
(Part of Wednesday #1 here)
Common Land Features Created By Erosion (continued) : Common Land Features Created By Erosion (continued) River Deltas
Occur at the end of rivers where much of the sediment still found in the flowing river water gets deposited as the flowing water runs into water flowing in the opposite direction or not at all.
This picture shows how each year the delta will continue to grow off of islands and sediment land forms created in previous years.
(Still Wednesday #1)
Common Land Features Created By Erosion (continued) : Common Land Features Created By Erosion (continued) Sand Dunes
Created on shorelines and desserts from winds depositing sand and other sediment.
Depending on the wind direction, more and more sand will be deposited and the dune will grow, or the sand will be carried away and the dune will shrink in size.
Types of Weathering : Types of Weathering Physical Weathering
This type is caused by rocks splitting and cracking due to water.
When water freezes in the cracks of rocks it expands and makes the cracks wider.
When the ice melts the cracks are too wide and the rock breaks down.
Physical weathering is the physical change of a rock’s shape from a larger piece to a smaller piece.
(Wednesday #2)
Types of Weathering : Types of Weathering Chemical Weathering
This happens when minerals in a rock have a chemical reaction with other materials and changes completely into a new substance or is dissolved.
This picture of the Parthenon suffers from chemical weathering as acids in the rain dissolve the marble made from a limestone base. The limestone reacts to acids, even mild ones in rainwater, and will dissolve.
(Thursday #1)