What is a sinkhole? Sinkholes are depressions or holes in the land surface that occur throughout west central Florida. They can be shallow or deep, small or large, but all are a result of the dissolving of the underlying limestone.

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Erosion Erosion is the process by which the surface of the Earth gets worn down. ence/terc/content/visualizations/es1205/es 1205page01.cfm?chapter_no=visualizatio nhttp:// ence/terc/content/visualizations/es1205/es 1205page01.cfm?chapter_no=visualizatio n

Weathering Mechanical and Chemical

Factors that influence weathering 1. Composition Some materials are harder than others (quartz) Some materials are more resistant to weathering (calcite) 2. Structure Fractured and fine grained rock weathers faster 3. Topography Severe temperatures expose fresh material 4. Climate Moisture and heat accelerates weathering

Why is weathering important? It produces sedimentary rocks and soil Mineral resources – ore deposits

MechanicalWeathering Mechanical Weathering

Mechanical Weathering Physical forces break rock into smaller and smaller pieces without changing mineral composition.

Six types of Mechanical weathering 1. Frost Wedging 2. Unloading or exfoliation 3. Thermal Expansion or exfoliation 4. Salt formation 5. Biological Activity 6. Abrasion

1. Frost Wedging Freezing and thawing of water in cracks Ice expands by 9% This occurs in mountainous regions and colder areas Talus: material produced by frost wedging at the base of a mountains forming a talus slope

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Talus slope from mechanical weathering

2. Unloading or exfoliation Pressure of overlying rock is removed by weathering Like the peeling of an onion This occurs because there is a reduction in pressure There is usually slab-like layers or loose sheets of rock Can be removed by erosion or ice sheets

3. Thermal Expansion Rock is a poor conductor of heat so the outside expands more than the inside This occurs in the desert – temperatures can vary by 30 degrees. This can causes exfoliation

Called: Exfoliation domes

4. Salt-crystal growth Salt crystal growth called haloclasty Water in rock openings is saline, the water evaporates and it leaves behind salt crystals which when heated expand and exert pressure on the rock. Causes granular disintigration This is common along the coast or the sides of the road in places where they salt the road

honeycomb weathering

5. Biological Activity Roots growing into the cracks and joints in rocks Earthworms and termites making tunnels People building roads, cultivating the land, exposing rocks to other types of weathering

6. Abrasion Abrasion refers to the breaking and grinding away of solid rock by collisions with moving particles. Abrasion takes place in many environments: fast-moving streams, beaches subject to storm waves, desert environments with high winds and beneath glaciers that are loaded with fragments of rock.

Just plain old gravity can be a factor of mechanical weathering like seen in these pictures…

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