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By: Adriana Montoya

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Presentation on theme: "By: Adriana Montoya"— Presentation transcript:

1 By: Adriana Montoya

2 JOINTS AND ITS MEANING…  Joints are fractures along which no appreciable displacement has occurred.  Most common rock structures are fractures called joints. images/columnar_layers-703634.jpg

3 Joints continued… Parallel group joints es/fsoster/W2.jpg  Although some joints occur in roughly parallel groups. /air/122-25v.jpg

4 Columnar Joints Columnar joints are joints that form when igneous rocks cool and develop shrinkage fractures that produce elongated, pillar like columns. ology/images/columnar_joint.jpg

5 How joints are produced?  Most Joints are produced when rocks in the outermost crust are deformed.  Tensional and shearing stresses associated with crustal movements cause the rock to fail by brittle fracture.  Extensive joint patterns can also develop in response to relatively subtle and barely perceptible regional up warping and down warping of the crust.  Although jointed rocks present a risk to the construction of engineering projects.  For example, highways, and dams. %20Landscapes%20IV%20(Hong%20Kong%27s% 20landscapes)_files/photo19sm.jpg v/news/images/ g ges/SuperRedTan.gif

6 Chemical Weathering Many rocks are broken by two or even three sets of intersecting joints that slice the rock into numerous regularly shaped blocks. hlphoto/terreco/weathering.jpg mnTops.jpg Chemical Weathering tends to be concentrated along joints, and in many areas groundwater movement and the resulting dissolution in soluble rocks is controlled by joint pattern.

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