Transcript Slide 1
CHAPTER 11 MOUNTAIN BUILDING Roots: Erg = work (energy) Aesth = feeling (aesthetic) Ethno = race (ethnic) Eu = good (euphoria) Ex = out (exit) Extra = outside (extraterrestrial) Fact = make (artifact) Fer = carry (ferry) Fid = faith (confide) Flect = bend (deflect) CH. 11.1 ROCK DEFORMATION Mostly happens at Plate Boundaries. Deformation = all changes in the original shape and/or size of a rock body. What affects whether a rock will deform?: • • • • temperature confining pressures rock type time Temperature & Pressure Brittle Deformation • Deform when near the surface. • Deform under lower temperatures and pressures. • Break instead of folding. Temperature & Pressure Ductile Deformation • Deform at depth. • Deform under higher temperatures and pressures. • Fold, bend and flatten. Rock Type Rocks like granite and basalt that are made of strong structures usually fail by brittle deformation. Rocks made of weaker sedimentary rocks usually fail by ductile deformation. Time Forces that are unable to deform rock at first may be able to affect a change over long periods of time. TYPES OF STRESS! Compressional Stress = rocks are squeezed. Shear Stress = rocks are distorted. Tensional Stress = rocks are pulled apart. Types of Folds Monocline = step-like Syncline = trough-like Anticline = arching Monocline, Anticline, or Syncline? You decide! Syncline Syncline Monocline Syncline Anticline Anticline Faults Normal = hanging wall drops Reverse = hanging wall lifts Thrust = reverse of < 45o Strike-slip = horizontal movement Joints = no movement CH 11.2 Types of Mountains FOLDED MOUNTAINS Formed primarily by folding. Most often associated with compression. Fault-Block Mountains = large scale normal faults Graben Horst Dome Mountains = circular or elongated structure produced by upwarping. Basin = circular shape produced by downwarping. CH 11.3 Mountain Formation Mostly convergent boundary formations. Accretion = when crustal fragments collide with a continental plate and become stuck to or embedded into the plate. Mountain Building http://www.learner.org/vod/vod_window.html?pid=318 Himalayan Mountains Formed when India collided with southern Asia GoogleEarth all the way down and show Mt Everest from above and side views. Divergent Mountains = mountains built at divergent boundaries Example: Mid-Atlantic ridge Google earth mid atlantic ridge go all the way to the base and turn up then scan horizon Terrane = crustal fragment that has a geologic history distinct from the rocks around it. Figure 16 Pg 322 Continental Accretion - Terrane http://www.geology.um.maine.edu/geodynamics/analogwebsite/UndergradProjects2005/Perry/html/introduction.html Isostasy = the gravitational balance of floating continental plates. Floating block interactive animation http://www.ikswonad.com/portfolio/index.php?show=isostasy Alps Atlas Andies Great Dividing Range Appalachians Himalayas Mountains of the World Rockies Urals Zagros Urals Appalachians Alps Rockies Himalayas Atlas Zagros Andies Great Dividing Range