Exam 2 - Exam 2 Surface Processes Exam November 4th Mass...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Exam 2 Surface Processes Exam – November 4 th Mass Wasting Gravity Gravity acts everywhere, pulling everything in a direction toward the center of the earth o On a flat surface gravity acts downward o So long as the material remains on the flat surface it will not move under the force of gravity o On a slope, gravity can be resolved into two components: a component perpendicular to the slope and a component tangential to the slope Mass Wasting o If the sheer component of gravity is stronger than the forces holding an object on the slope, then the object will move down-slope Angle of repose o Each material has a different angle of repose o Sand – can go up to 42 degrees – relatively steep slope o Cement – 34 degrees o If something is on a slope and within its angle of repose, then it does not move, if it goes over the angle of repose gravity pulls things downward until the angle of repose is reestablished Landform Development o Down slope movement of rock, regolith (rocks and soil) and soil under the direct influence of gravity o Geologic processes that often follows weathering o Combined effects of mass wasting and running water produce stream valleys Slopes change through time o No minimum angle is required for mass wasting to occur o Most rapid and spectacular mass-wasting events occur in areas of rugged, geologically young mountains High mountains with clear signs of gravity and erosion working to bring materials downward o Mass wasting and erosional processes slowly lower the land surface o Once mass wasting occurs, the land is fresh (no vegetation or weather) so it looks very different than the surrounding areas. Over time, the vegetation will grow back though and the land will blend in. So you must look at the actual
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
patterns of the land to determine if mass wasting occurred – hence the land is weak. Controls and Triggers of Mass Wasting o 1- Role of water Diminishes particle cohesion (friction) Saturates many particles, and separates then so the water can go between particles, if too saturated then the particles can’t hold together anymore Causes the angle of repose to decrease significantly Water adds weight o 2- Oversteepening of slopes – slope angle Stable slope angle (angle of repose) is different for various materials Oversteepened slopes are unstable When roads are carved into the sides of mountains, then the slope of the mountain is too steep, over the angle of repose, so erosion and gravity pulls the rocks of the mountain down onto the road o 3- Removal of anchoring vegetation Vegetations has roots which make the slopes more stable Removal of vegetation weakens the slope o 4- Earthquakes Can cause liquefaction – water-saturated surface materials behave as fluid-like masses that flow Mass Wasting structures o Source area – where the material leaves o Deposition area – where the material is accumulated Classification of Mass Wasting Processes o Type of material Mud, earth rock o Type of motion Fall
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern