ANNOUNCEMENTS THIS WEEK Thursday class: Please bring scissors! NEXT WEEK Wed CLASS: Bring a mechanical compass if have one. Neighbor MEET & GREET 1. Each person take out a sheet of paper and write LEGIBLY your name and the two most interesting things about you (hobbies, travels, background, etc.) (You have 1 minute to do this!) 2. Each person partner with ONE other person in the room (odd person out partners with ME!) and share your name and interests with this person. Make sure both people get to share! (You have a total of 4 minutes!) 3. Form groups of SIX. (Move desks so you can all face each other.) Within these groups, each person will share with the group the name and top two interests OF THEIR PARTNER. (You have 30 seconds to present and then a few minutes after EVERYONE has presented to discuss). Turn to Neighbor: What is the difference between accretionary wedges and terranes? 1
Deformation type Causes Results Deformation type Causes Results Elastic temporary deformation Stress not greater than elastic limit of rock Strain released and shape returns to normal Brittle permanent break Plastic permanent ductile deformation Stress greater than yield point of rock (usually colder temperatures nearer surface rapid stress application) Stress greater than elastic limit of rock (usually higher temperatures deeper underground stress applied slowly over long time) Strain released with break in rock (faulting) Strain is permanent (folding) Turn to Neighbor: Using a toothpick, demonstrate and explain to each the three different types of deformation that a rock can experience. Using two different-colored pieces of paper, demonstrate to yourself the principle of superposition. Where is the oldest rock found? 2
Erosion of Sedimentary Rocks ANIMATION 3
Using two different-colored pieces of paper, demonstrate to yourself anticlines and synclines. Where is the oldest rock found for each? Using two different-colored pieces of paper, demonstrate to yourself ERODED anticlines and synclines. What pattern do the sheets of paper (layers of rock) make when viewed from above? Where is the oldest rock found for each? 4
What do Domes and Basins look like as they form? Once their tops are eroded flat, what do they look like from the top? From the side? Where are the oldest rocks found? Using two different-colored pieces of paper, demonstrate to yourself a North-Plunging Anticline. 5
Use scissors to cut the top off your ERODED North-Plunging Anticline. What pattern do the sheets of paper (layers of rock) make when viewed from above? Where are the oldest rocks? Which direction does the ERODED North-Plunging Anticline U/V tip point relative to the plunge direction? Using two different-colored pieces of paper, demonstrate to each other an ERODED North-Plunging Syncline. Use scissors to cut the top off. Which direction does the ERODED South-Plunging Syncline U/V tip point relative to the plunge direction? 6
Y O O Y O Syncline North-Plunging Anticline South-Plunging Syncline Y Dorset, England Newfoundland, New Jersey California s Borrego Desert Folded Sediments Outside Calico Ghost Town, Southern California 7
SHEAR SHEAR Left-Lateral STRIKE-SLIP Right-Lateral STRIKE-SLIP Fault Types ANIMATION REVERSE NORMAL HW FW Compression FW Tension HW REVERSE NORMAL HW FW FW HW Tension Compression 8
Glacier National Park Faulting 52 Wallace Creek 53 9
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DEMO: Fault-Block Mountains 11
Looking South (from the western edge of the Basin and Range where it meets the flat beds of the Colorado Plateau) San Andreas Fault System Formation Animation Pacific Plate Recent HistoryAnimation 12
Images (c) 2001, 2002 Andrew Alden, licensed to About.com, Inc. Sandstone 50 Ma Mt Diablo 13
The Adirondack Mountains of Northern New York Stress types Plate boundaries Fault types Crustal thickening or thinning or both/none? Mountain types (if any) Compression Convergent Reverse (+ thrust) Thickening Fold and Thrust Tension Divergent Normal Thinning Fault-Block Shear Transform Strike-slip None None 14
We have now completed this week s question sheet. On your own, review each question again. I recommend that you write out your answers (synthesize your thoughts and notes and put the answers into your own words). If something doesn t make sense or to just get some feedback, come see the tutors or me during my office hours. Remember: half of next week s quiz will contain any question from the question sheet. Activity: Folding Box Diagram and Fault Diagrams 15
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