Weathering Weathering Students will be able to describe and give examples of chemical and physical weathering.

Weathering The breakdown of materials on Earth’s crust into smaller pieces.

Two Types of Weathering Venn Diagram Mechanical Weathering Chemical Weathering

Mechanical Weathering Process by which rocks are broken down into smaller pieces by external conditions. Types of Mechanical Weathering –Frost Action Ice Wedging –Wind –Water –Abrasion –Plant growth –Animals

Ice wedging: water is confined in cracks or pores then freezing on the rock surface and downward into the rock, solidifying and expanding deeper inside, thus wedging the rocks apart.

Ice Wedging

Ice wedging slowly breaks up this sedimentary rock into unusual shapes.

Abrasion Water Moves rocks, making them hit each other Wind Blows sand against rocks Gravity Rocks rub against each other as they slide downhill

These rocks have been blasted by wind and sand causing them to become rounded. WIND

Water Rivers, streams, and runoff

This is a picture of the Half Dome. The rock is peeling away from the mountain in layers just like an onion. This is exfoliation. (Abrasion)

Plant Growth

Plant growth The tree is growing in the rock and soon the rock will break apart because of the tree roots.

Animals

Chemical Weathering The process that breaks down rock through chemical changes. Greatest in warm/wet environments. The agents of chemical weathering –Water –Acid in ground water –Living organisms –Acid Precipitation (rain, snow) –Oxygen

Water Water weathers rock by dissolving it

Acids in Groundwater: Caves and caverns typically form in limestone stalactites - hang from ceiling stalagmites - on the groundCaves

The lichen covered boulder produces a habitat for mosses and eventually higher plants which continue the breakdown of the rock surface by producing weak acids.

Acid Precipitation 1908 to 1969 Acid precipitation has eaten away this limestone statue. Rain, sleet, ice snow, that contains a high concentration of acids.

Oxygen the second most common element in the air we breathe, reacts with iron in minerals to form iron oxide minerals, e.g. hematite (rust). As many minerals contain iron, it is not unusual to see red-colored rocks like the example from Arches National Park shown here.

Weathering and Erosion Video 1.What is an example of weathering and erosion in the restroom? 2.Weathering means _________________. Erosion means ____________________. 3.What 3 ways does water cause weathering? What are the 2 types of weathering? What are the 2 types of erosion?

Karst Topography A type of landscape in rainy regions where there is limestone near the surface, characterized by caves, sinkholes, and disappearing streams. Created by chemical weathering of limestone

Karst Topography Video 1.What are karst topography examples? 2.Why is pollution of karst land forms harmful to the environment? 3.Where are there a lot of karst environments? 4.How does pollution affect cave systems outside of urban environments? 5.What university is the leader in karst topography research? 6.Where can you find materials on karst topography online?

Features of Karst: Sinkholes

Features of Karst: Caves

Features of Karst: Disappearing Streams