Earth Structure
True or False: The outer core is solid.
False. The outer core is liquid. We know this because S-waves from earthquakes can't travel through the outer core.
True or false: Scientists have not always believed in the theory of plate tectonics.
True
True or false: A mineral can be man-made.
False.
True or false: All sedimentary rocks have fossils in them.
False.
True or false: All igneous rocks form from lava or magma.
True.
Name three of the layers within Earth, in order from the surface to the center.
Crust, mantle, core
OR
Lithosphere, asthenosphere, mesosphere, outer core, inner core
Name a place on Earth that is tectonically active.
Ring of Fire, west coast of USA, middle of oceans where mid-oceanic ridges are, east Africa, etc.
Name three tools geologists use to identify minerals.
Name a sedimentary rock.
Conglomerate, sandstone, shale, chalk, coal, limestone.
Name an igneous rock that you see used as a building material a lot in Maine.
Granite!
How have meteorites helped us understand the composition of Earth's interior?
Meteorites are thought to be "leftovers" from the formation of the solar system. Stony meteorites are similar in composition to Earth's crust; iron meteorites are thought to be similar in composition to Earth's core.
Explain how convection currents move lithospheric plates.
Convection currents lift hot plastic rock from the lower mantle and raise it towards the surface; they then take cooled plastic rock from the asthenosphere and return it to the lower mantle for reheating. Heating water to a boil in a pot uses convection as well.
Explain why color is not the most useful physical property of a mineral.
1. Weathering (physical or chemical)
2. Erosion (water, wind, ice, gravity)
3. Transportation (water, wind, ice, gravity)
4. Deposition (water, wind, ice, gravity)
5. Cementation
Explain how crystal size tells us where an igneous rock formed.
Igneous rocks with large crystals cooled slowly in the ground; igneous rocks with itty-bitty crystals cooled quickly on Earth's surface.
Give three correct facts about each of the following internal Earth layers:
crust
mantle
core
crust: outermost layer; composed of continental and oceanic crust; rich in aluminum, silicon, oxygen, iron; solid; coolest layer
mantle: middle layer; plastic-like solid; has convection currents, which move the plates; rich in iron, magnesium, iron
core: center layer; inner part is solid and outer part is liquid; rich in iron and nickel; hottest layer
Explain plate tectonics theory.
Plate tectonics theory states that earth's lithosphere is broken up into plates of varying size, and that these plates move over Earth's surface because of convection currents below. Plates interact in three ways: Convergent, divergent, and transform. Plate tectonics explains why we have mountains, volcanoes, and earthquakes.
Explain how graphite and diamond can be made of only carbon, yet one is very soft and the other is very hard.
It has to do with the way the carbon atoms are arranged within the minerals, and the strength of those chemical bonds. Graphite's carbon atoms are bonded weakly; diamond's carbon atoms are bonded strongly.
In what depositional environment might a fossiliferous limestone form?
Shallow marine.
How can we tell if an igneous rock formed from melted continental crust or from melted oceanic crust.
You can tell by the overall color of the rock, which is reflected in the minerals that make up the rock. In general, light-colored igneous rocks come from continental crust whereas dark-colored igneous rocks from from oceanic crust.
After Earth was accreted, radioactive elements combined with pressure from gravity turned Earth into a sphere of molten rock. When this happened, denser elements such as nickel and iron sunk towards the center, while lighter elements such as aluminum and silicon floated to the surface.
Given the current tectonic environment in east Africa, predict what will happen over the next few million years in this part of the world.
East Africa is a newly-formed divergent plate boundary. Over the next few million years, it should continue to spread apart, eventually forming a new ocean.
Explain why an understanding of minerals is needed before you study rocks.
Rocks are made of minerals. Rock names are based in part on what minerals are within them, so in order to identify a rock, you need to first be able to identify the minerals within it.
Explain why fossil are not always preserved in rock.
There could be several reasons, including:
-animals scavenged the carcass before it could be preserved
- the carcass rotted before it could be preserved
- the carcass was destroyed by metamorphism
Explain why Guatemala's Fuego Volcano is erupting differently than Hawaii's Mount Kilauea.
Guatemala's volcanism is related to the subduction of oceanic crust underneath continental crust. This produces volcanoes with lava that has more silica in it, which makes it more explosive. These volcanoes also produce a lot of ash which, when mixed with water, creates lahars, which can devastate local communities. Hawaii's volcanoes are the result of crustal melting by a hot spot. Melted oceanic crust has very little silica in it, so the lava is more fluid. While destructive to things within its path, its impact on communities is not as widespread because people can more easily move out of the lava's path.