1. Journal #14 Compare and contrast ordinary wells and artesian wells. What is porosity? What is permeability?

3. Chemical Weathering As groundwater passes through permeable rock, minerals in the rock dissolve. The warmer the rock is and the longer it is in contact with water, the greater the amount of dissolved minerals. Water that contains high concentrations of dissolved minerals (calcium, magnesium and iron) is called hard water. Water that contains low concentrations of dissolved minerals is called soft water.

4. Many People Do Not Like Hard Water More soap is needed to produce suds in hard water Metallic taste Household appliances or fixture may be damaged by the buildup of mineral deposits.

5. What kind of water is in Mojave?

6. Results of Weathering One way that minerals become dissolved in groundwater is through chemical weathering. As water moves through soil and other organic materials, the water combines with carbon dioxide to form carbonic acid. This acid chemically weathers rock and dissolved the minerals in the rock.

7. Caverns Rocks that are rick in calcite, such as limestone, are very vulnerable to chemical weathering. Vertical and horizontal cracks cut through the layers. As groundwater flows through these cracks, carbonic acid slowly dissolves the limestone and enlarges the cracks. Eventually, a cavern may form. New Mexico, Carlsbad Caverns

8. A cavern is a large cave that may consist of many smaller connecting chambers.

9. Sinkholes A circular depression that forms at the surface when rock dissolves, when sediment is removed, or when caves collapse is a sinkhole. Most sinkholes form when limestone dissolves in weak areas of rock. A small depression forms it may eventually collapse. Collapse sinkholes may develop abruptly and cause extensive damage.

11. Natural Bridges When the roof of a cavern collapses in several places, a relatively straight line of sinkholes forms. The uncollapsed rock between each pair of sinkholes forms an arch of rock called a natural bridge. When a natural bridge first forms, it is thick, but erosion causes the bridge to become thinner. Eventually, the natural bridge may collapse.

13. Karst Topography Irregular topography caused by chemical weathering of limestone by groundwater is called karst topography.

14. Karst Topography Common features include many closely spaced sinkholes and caverns. Stream often disappear into cracks in the rock and then emerge in caves or through other cracks. Usually form in areas where it is humid and where limestone formations exist at the surface. The groundwater dissolves the limestone.

15. Lets Review What is the difference between hard water and soft water? What are some reasons why people do not like hard water? How does ground water weather rocks?

16. Review: How does a cavern form? How does a sinkhole form? How are sinkholes related to natural bridges?

17. Review: What is this an example of?

18. Chemical Weathering Lab