Science Vocab
What does Pangaea mean?
"All lands"
What are the steps by which mineral deposits form along mid-ocean ridges?
1. Ocean water seeps through cracks in the crust 2. The water gets heated by magma and forms into a solution 3. The solution billows out of the "chimneys" 4. When the hot solution hits the cold sea, minerals crystallize and settle to the ocean floor
Describe two ways in which limestone can form.
1. When animals in the ocean die and their shells pile up as sediment one the ocean floor and over time, the layers grown and the pressure of the layers compact together. Some of the shells dissolve forming a calcite solution that seeps into spaces between shell fragments. The dissolved material comes out of the solution, forming calcite. The calcite cements the shell particles together, forming Limestone. 2. From sediments made of the skeletons of microscopic living things found in the ocean.
What was Wegener's theory of continental drift?
All the continents had once been joined together in a single landmass and have since drifted apart.
What are alloys, and why are they useful?
An alloy is a solid mixture of two or more metals. They are useful because one metal combined with another metal can make special properties.
Coal deposits have also been found beneath the ice of Antarctica. But coal only forms in warm swamps. Use Wegener's theory to explain how coal could be found so near the poles.
Antarctica was once closer to the equator and was warmer.
Which properties of a rock may change as the rock becomes metamorphic?
Appearance, texture, crystal structure, and mineral content
How are basalt and granite different in their origin, texture, and mineral composition? How are they similar?
Basalt: Origin: Extrusive Texture: Crystals too small to be seen without a microscope Mineral Composition: Dark Granite: Origin: Intrusive Texture: coarse-grained rock Mineral Composition: Light Both are rocks, have silica in them, and both are common.
What was the main reason scientists rejected Wegener's theory of continental drift?
Because he couldn't provide a satisfactory explanation for the force that pushes or pulls continents.
Why are some igneous rocks dark and others light?
Because of the different mineral compositions
Why are you less likely to find fossils in metamorphic rocks than in sedimentary rocks?
Because the fossils would have changed or been destroyed as the rock was heated up and squished.
How does pressure change rock?
By turning any rock into a metamorphic rock and squishing it.
What are the three major kinds of sedimentary rocks?
Clastic rocks, organic rocks, and chemical rocks
Describe how convection currents form.
Convection currents form when the heating and cooling of the fluid, changes in the fluid's density, and the force of gravity combine.
What are some of the ways that people use gems and metals?
Decoration, mechanical parts, and grinding and polishing
How did Wegener use evidence based on fossils to support his theory that the continents had moved?
He took the fossil, for example, Glossopteris, and explained how they appeared on other continents since the couldn't have been carried by wind because it was to large or water because it was too fragile.
In smelting, what causes a metal to separate from its ore?
Heat
What are some of the differences and similarities between the mantle and the core? Explain.
Mantle: middle of the Earth Core: center of the earth; causes magnetic field Both: have two parts; made up of hot metals
If plate motion compresses part of the crust, what landforms will form there in millions of years? Explain.
Mountains and hills
Describe the three types of seismic waves.
P waves: earthquake waves that compress and expand the ground like an accordion S waves: earthquake waves that vibrate from side to side as well as up and down Surface waves: move more slowly than P and S waves but produce the most severe ground movements
What major event in Earth's history began about 225 million years ago? Explain.
Pangaea began to break apart and the continents began to form.
What are the three types of heat transfer?
Radiation, conduction, and convection
How does the energy from an earthquake reach Earth's surface?
Seismic waves carry the energy of an earthquake away from the focus, through Earth's interior, and across the surface.
Compare and contrast shale and sandstone. Include what they are made of and how they form.
Shale: tiny particles of clay (no cementation) Sandstone: small particles of sand (cementation) Both: formed from deposition
What are the three main types of stress in rock?
Shearing, tension, and compression
Describe how the cooling rate of magma affects the size of the mineral crystals formed.
Slow cooling = formation of large crystals Fast cooling = formation of small crystals
Explain what causes an igneous rock to have a fine-grained or coarse-grained texture.
Slow cooling causes an igneous rock to have a coarse-grained texture and rapid cooling causes a fine-grained texture.
What process is used to separate useful metals from ores?
Smelting
A miner finds a vein of silver. Describe a process that could have formed the vein.
Solutions of hot water and metals followed cracks within the rock. The metals then crystallized into veins.
Describe the movements that occur along each of the three types of faults.
Strike-slip fault: the rocks on either side of the fault slip past each other with little up-or-down motion normal fault: one block of tock lies above the fault while the other block lies below the fault reverse fault: has the same structure as a normal fault, but the blocks move in the opposite direction
Describe three different kinds of mines.
Strip mines: earth-moving equipment scrapes away soil to expose ore Open pit mining: miners use giant earth-moving equipment to dig a huge pit Shaft mines: often have a network of tunnels that extend deep into the ground, following the veins of ore
There is a divergent boundary that runs through the African plate. Predict what could eventually happen along this boundary.
The African plate may break apart.
The mid-ocean ridge extends into the Red Sea between Africa and Asia. What do you think will happen to the red Sea in the future? Explain your answer.
The Red Sea will grow larger because the mid-ocean ridge is constantly expanding and creating new rock.
What are metamorphic rocks classified by?
The arrangement of the grains that make up the rock.
What characteristics are used to classify metamorphic rocks?
The arrangement of the grains that make up the rock.
What happens to convection currents when a fluid reaches a constant temperature?
The convection currents will eventually stop when all of the material has reached the same temperature.
How does Earth's surface change as a result of movement along faults?
The crust folds and breaks as a result of movement along faults.
What is the difference between extrusive and intrusive rocks? Give an example of each.
The difference between extrusive and intrusive rocks are extrusive rocks form from lava that erupted onto Earth's surface and Intrusive rocks form when magma hardens beneath Earth's surface. Example of extrusive rock: Basalt Example of intrusive rock: Granite
What will happen to the flow of hot rock in Earth's mantle if the planet's core eventually cools down? Explain your answer.
The hot rock will stop flowing because, without heat, it will eventually stop.
What is a rock?
The inorganic/organic components of Earth's crust that are subjected to change by heat, pressure, erosion, and water.
What are the layers that make up Earth? Write a sentence about each one.
The layers that make up Earth are the crust, mantle, outer core, and inner core. The crust is a layer of rock that forms Earth's outer skin. The mantle's two parts are the lithosphere and the asthenosphere. The outer core is a layer of molten metal that surrounds the inner core. The inner core is a dense ball of solid metal.
What is the role of the mid-ocean ridge in sea-floor spreading?
The mid-ocean ridge starts the process of sea-floor spreading.
What is the evidence for sea-floor spreading?
The mid-ocean ridge, molten material, magnetic strips, and drilling samples.
What system do geologists use today for rating the magnitude of an earthquake?
The moment magnitude scale
Describe the process of subduction at a deep-ocean trench.
The ocean floor sinks beneath the crust into the mantle. Convection currents under the lithosphere push new crust that forms at the mid-ocean ridge away from the ridge and toward a deep-ocean trench.
Describe the process by which metamorphic rocks form.
The process is by heat and pressure deep beneath Earth's surface.
Once sediment has been deposited, what processes change it into sedimentary rock?
The processes of compaction and cementation
What are two things that geologists study about Earth?
The processes that create Earth's features and search for clues about Earth's history
Where would you expect to find the oldest rock on the ocean floor? Explain your answer.
The rock farthest away from the mid-ocean ridge because the new rock comes out of the mid-ocean ridge and cools and expands.
Describe how energy released at an earthquake's focus, deep inside Earth, can cause damage on the surface many kilometers from the epicenter.
The shaking can be so violent that it affects areas far away from the epicenter.
What happens in Earth's interior to produce Earth's magnetic field? Describe the layers of the interior where the magnetic field is produced.
The spinning of the inner core. The liquid outer core and the solid inner core.
What is the theory of plate tectonics?
The theory of plate tectonics explains the formation,movement, and subduction of Earth's plates.
What are igneous rocks classified by?
Their origin, texture, and mineral composition.
What are two main ways in which minerals form?
Through crystallization of melted materials and through crystallization of materials dissolved in water.
What are the different types of boundaries found along the edges of Earth's plates?
Transform, divergent, and convergent boundaries
In general, what happens to the density of a fluid when it becomes hotter?
When the fluid becomes hotter, the fluid becomes less dense.
fault
a break in Earth's crust where slabs of crust slip past each other
base isolated building
a building designed to reduce the amount of energy that reaches the building during an earthquake
inner core
a dense ball of solid metal
syncline
a fold in rock that bends downward in the middle to form a bowl
anticline
a fold in rock that bends upward into an arch
stress
a force that acts on rock to change its shape or volume
plateau
a large area of flat land elevated high above sea level
mantle
a layer of hot rock below the boundary
outer core
a layer of molten metal that surrounds the inner core
crust
a layer of rock that forms Earth's outer skin
asthenosphere
a layer of soft material that can bend like plastic
magnitude
a measurement of earthquake strength based on seismic waves and movement along faults
Inorganic
a mineral that doesn't come from materials that were once part of a living thing
cleavage
a mineral that splits easily along flat surfaces
mineral
a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition
Richter scale
a rating of the size of seismic waves as measured by a particular type of mechanical seismograph
atoll
a ring-shaped coral island found far from land
granite
a rock that has larger crystals than basalt and is not as dense
Porphyritic texture
a rock with large crystals scattered on a background of much smaller crystals
geologist
a scientist who studies the forces that make and shape planet Earth
clastic rock
a sedimentary rock that forms when rock fragments are deposited in thick layers
rock cycle
a series of processes on Earth's surface and inside the planet that slowly change rocks from one kind to another
element
a substance composed of a single kind of atom
aftershock
an earthquake that occurs after a larger earthquake in the same area
deformation
any change in the volume or shape of Earth's crust
folds
bends in rock that form when compression shortens and thickens part of Earth's crust
moment magnitude scale
can be used to rate earthquakes of all sizes, near or far
tsunamis
caused by an earthquake if it is strong enough; the water displaced by the quake forms large waves
basalt
dark, dense rock with a fine texture
fracture
describes how a mineral looks when it breaks apart
Mercalli scale
developed to rate earthquakes according to their intensity
P waves
earthquake waves that compress and expand the ground like an accordion
S waves
earthquake waves that vibrate from side to side as well as up and down
Metamorphic Rock
formed when an existing rock is changed by heat, pressure, or chemical reactions
Igneous Rock
forms from the cooling of molten rock
chemical rock
forms when minerals that are dissolved in a solution crystallize
Sedimentary Rock
forms when particles of other rocks or the remains of plants and animals are pressed and cemented together
organic rock
forms where the remains of plants and animals are deposited in thick layers
What are Minerals Identified by?
hardness, color, streak, luster, density, crystal shape, cleavage and fracture, special properties
crystal
has flat sides that meet at sharp edges and corners
What can change any rock into a metamorphic rock?
heat and pressure deep beneath Earth's surface
extrusive rock
igneous rock formed from lava that erupted onto Earth's surface
intrusive rock
igneous rock that formed when magma hardened beneath Earth's surface
foliated
metamorphic rocks that have their grains arranged in parallel layers or bands
surface waves
move more slowly than P waves and S waves
liquefaction
occurs when an earthquake's violent shaking suddenly turns loose, soft soils into liquid mud
erosion
occurs when running water or wind loosen and carry away the fragments of rock
What are the three major characteristics that geologists use to identify igneous rocks?
origin, texture, and mineral composition
grain
particles of minerals or other rocks
coral reef
produce skeletons that grow together to form a structure
tension
pulls on the crust, stretching rock so that it becomes thinner in the middle
Mohs hardness scale
ranks 10 minerals from softest to hardest
seismograph
records the ground movements cause by seismic waves as they move through the Earth
strike-slip fault
rocks on either side of the fault slip past each other sideways with little up-or-down motion
earthquake
shaking and trembling that results from the movement of rock beneath Earth's surface
constructive force
shapes the surface by building up mountains and landmasses
destructive force
slowly wears away mountains and, eventually, every other feature on the surface
sediment
small, solid pieces of material that come from rocks or living things
compression
squeezes rock until it folds or breaks
shearing
stress that pushes a mass of rock in two opposite directions
continent
the 7 great landmasses that are surrounded by oceans
streak
the color of a mineral's powder
normal fault
the fault is at an angle so the foot wall lies below above the fault and the hanging wall lies below the fault
pressure
the force pushing on a surface or area
flourescence
the glow under ultraviolet light
hanging wall
the half of the fault that lies above
foot wall
the half of the fault that lies below
texture
the look and feel of the rock's surface
rock
the material that forms Earth's surface
focus
the point beneath Earth's surface where rock that is under stress breaks, triggering an earthquake
epicenter
the point on the surface directly above the focus
deposition
the process by which sediment settles out of the water or wind carrying it
cementation
the process in which dissolved minerals crystallize and glue particles of sediement together
compaction
the process that presses sediments together
reverse fault
the same structure as a normal fault, but the blocks move in the opposite direction
geology
the study of planet Earth
lithosphere
the uppermost part of the mantle and the crust together
compound
two or more elements that are combined so that the elements no longer have distinct properties
luster
used to describe how a mineral reflects light from its surface
seismic waves
vibrations that travel through Earth carrying the energy released during an earthquake
fault block mountain
when normal faults uplift a block of rock
convergent boundary
when two plates collide
divergent boundary
when two plates separate
transform boundary
when two plates slide past each other