GEO 155 1st Edition Lecture 26 Outline of Last Lecture Volcanoes Outline of Current Lecture I Tectonism a Divergent Boundaries i Tension b Convergent Boundaries i Compression ii Overthrust Faults c How do you tell the difference d Folding i Anticlines ii Synclines iii Monoclines iv Other Erosional Features Current Lecture These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Tectonism Deformation of the Earth s crust o Force of moving plates can bend and break solid rock Faulting when the crust breaks Folding when the crust bends o Occurs at the plate boundaries Divergent Boundaries Tension Plates pull apart lengthening the crust Normal Fault upper side of the fault moves down o Friction leads to accumulated tension which creates a jerky motion that results in earthquakes o Results in mountain rangers with Horsts and Grabens Convergent Boundaries Compression Plates are pushed together shortening the crust Reverse Fault upper side of the fault moves upward o Exposed middle erodes quickly so you end with a rounded mountain Overthrust Faults Extreme compression One plate lifts up and over the other Difference between Divergent and Convergent Boundaries Follow the layers Check the angles Locate the upper side Determine course of movement Transform Boundary Sheer Transform Fault or Strike slip Fault Recognized by horizontal offset of features Folding Compression can lead to folding Usually sedimentary rock Helps us follow the layer and know what happens Anticlines Folded upward Ridge Synclines Folded downward Valley Monoclines Folded on one side Erosional Features Easily eroded o Reverse Inversion lowest point becomes the anticlines that are now the valleys and the highest points become the synclines that are now the ridges o Hogback when one side of a feature is from folding and the other is from erosion o Cuesta top layer erodes faster than the rest o Buttes and Mesas like cuestas but not all of the layer is eroded butte is when a smaller piece doesn t erode leaving a small pointed structure mesa is when a larger piece doesn t erode and looks more plateau like
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