What qualities are present at divergent boundaries? (1)
* small shallow earthquakes on boundaries * not many volcanoes * crust slightly shallower along plate boundary * symmetrical age — newer at boundary, gets older further away
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What qualities are present at convergent boundaries? (1)
* Earthquakes get shallower on side going under, get deeper as earth descends * Volcanoes along top plate parallel to boundary * Volcanic arc next to deep sea trench * Likely no symmetry, geochronology not related to convergent boundary
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What qualities are present at transform boundaries? (1)
* Lots of shallow earthquakes along the boundary * No volcanoes forming * Off-set streams, physical cracks on landscape * No formation or recycling of crust
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What rocks were present at Vasquez Rocks and what was the sorting like?
* Quartz, k-feldspar and amphibole were present * Rocks were sedimentary * Poor sorting — rocks vary greatly in size and indications of flash floods (high energy)
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What rocks were present at Devil’s Punchbowl?
* Sedimentary * Granite, andesite, biotite, k-feldspar, quarts, sandstone, gneiss, diorite * There is less variety than there used to be in ancient times
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What type of rock is best to build on for earthquakes?
Sandstone is best, unstable river gravel and artificial fill are the worst
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How do igneous rocks form and what do the different grain size/texture mean about the cooling rate?
* Form when molten rock cools and becomes solid * Cool slowly —> larger minearls (macrocrystalline) * Cool quickly —> smaller minerals (microcrystalline)
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What is the difference between intrusive, extrusive, and porphyritic rocks?
* Intrusive - tend to be macrocrystalline (cool inside Earth) * Extrusive - microcrystalline (cool outside Earth) * Porphyritic - microcrystalline with scattered large crystals
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What are the seven main igneous rocks and what are they made of?
What is the difference between detrial, organic and inorganic sedimentary rocks and how they form?
* Detrial — made of fragments of pre-existing rocks that have been broken down through weathering erosion (mudtsone, shale, sandstone, breccia and conglomerate) * Organic — made of organic material produced by fossils (calcite) * Inorganic — formed from sediment that precipitates water — only chemical sediment (rock salt and gypsum)
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What causes foliated vs non-foliated metamorphic rocks?
* Foliated — form as a result of regional metamorphism (usually directed pressure); greater degree of metamorphism → larger minerals; more metamprophism = more shiny * Non-foliated — macroscopic tecture, high temp WITHOUT direct pressure, likely consist of one mineral
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What is an epicenter vs a focal point?
* Epicenter — point on Earth’s sruface above focal point * Focal point — underground origin of the earthquake
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How do earthquakes occur?
* Plate tectonic motion builds up as strain within Earth taht releases along faults * Seismic waves originate at focal point and travel in all directions * Motion (slip) along fault is what people feel
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What is the stike vs the dip?
* Strike — line of intersection btwn inclinced plane of sedimentary bed and horizontal plane * Dip — maximum tilt angle of sedimentary bed
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What types of rocks on are Fiji Hill and when did they form?
* Topanga formation — sedimentary rock * Formed 13 million years ago (young) * Granite, quartz, k-feldspar, plagioclaste, biotite
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What types of clasts are present and how did the rocks move from the San Gabriel mountains?
* Moved as the mountain eroded through landslides and then moved by streams/erosion to where they are * Fragments are buried and then lithification occurs → uplift happens
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What is the geologic history of the Topanga formation?