Unit 4 Flashcards
Crust
solid rocks on earth surface (oxygen, silicon, aluminum, iron, igneous and metamorphic rocks)
Mantle
Flowing rocks (mostly silicates)
Outer core
liquid iron and nickel
Inner core
solid iron and nickel
Asthenosphere
the soft, flexible upper layer of the mantle, on which the tectonic plates move
Continental drift
the theory that all of Earth’s continents were once joined together into a single large landmass (Pangea), and then moved apart, forming the continents we see today
Convection
transfer of heat by movement of a fluid
Convection currents
movement within hot fluids, when the heat source is on the bottom, such as in a boiling pot of soup on the stove. Convection currents happen because the hotter material is less dense and rises; when it reaches the surface, it cools and becomes less dense, so it sinks. This rising and sinking creates a circular motion within the fluid.
Convergent plate boundaries
where two tectonic plates move towards each other
Divergent plate boundaries
where two tectonic plates move away from each other
Gondwana
the southern continent formed when Pangea split into two pieces
Laurasia
the northern continent formed when Pangea split into two pieces
Lithosphere
the rigid, brittle layer made up of the crust and the uppermost part of the mantle. It is broken up into pieces called tectonic plates.
Mantle convection
convection currents in the mantle that occur because hot rock in the lower part of the mantle is less dense and rises, and cooler rock in the upper part of the mantle cools, becomes more dense, and sinks. Mantle convection is thought to be the mechanism driving the movement of tectonic plates.
Mid-ocean ridge
a system of connected underwater mountain ranges that run throughout the world’s oceans. There is a rift valley in the center of the mid-ocean ridge, where magma rises up from the mantle, and pushes out to either side, producing seafloor spreading.
Pangea
(“all land”) the single huge supercontinent that existed 245 million years ago, when all of Earth’s continents were joined together
Seafloor spreading
the process by which new oceanic crust forms when magma rises up and solidifies at the mid-ocean ridges. The newer crust pushes the older crust out to each side, which is why the age of the sea floor increases with distance away from the mid-ocean ridges.
Subduction
the process by which one tectonic plate sinks below another, returning to the mantle, where the rock is re-melted. Subduction takes place at convergent plate boundaries. Oceanic crust, which is denser, will always subduct under the less dense continental crust.
Tectonic plates
large pieces of the lithosphere that slowly move on top of the asthenosphere. There are seven primary plates and many smaller ones. The seven primary plates are the African Plate, Antarctic Plate, Eurasian Plate, Indo-Australian Plate, North American Plate, Pacific Plate, and South American Plate.
Tectonic plate boundary
a place where two tectonic plates meet
Transform plate boundary
where two tectonic plates slip past each other, moving in opposite directions
Atmosphere
The layer of air that surrounds the Earth (like a blanket). The atmosphere is made up of a mixture of gaseous elements and compounds and a small amount of tiny solids and liquids. The atmosphere is held close to Earth due to gravity.
Thermosphere
The atmospheric layer between the mesosphere and the exosphere where the molecules contain the most heat energy; the Northern and Southern lights, known as the auroras are found here. The ionosphere; the temperature increases as altitude increases.
Mesosphere
The middle layer of Earth’s atmosphere where most meteoroids burn up. The temperature decreases as altitude increases.
Jet stream
“Rivers” of high-speed air in the atmosphere, found in the top section of troposphere/early stratosphere. It affects air masses and affects aircraft by speeding or slowing their path.
Ozone layer
A layer of a special kind of oxygen (ozone = O3) found in the stratosphere that protects life on Earth from the sun’s harmful ultraviolet rays
Stratosphere
The second layer from the Earth’s surface. It contains the ozone layer. The temperature increases as altitude increases due to the ozone layer’s absorption of ultraviolet rays from the sun.
Troposphere
The lowest layer of the atmospheric, containing about 75% of all the air in the atmosphere. It contains the air we breathe and is where weather, clouds, and air pollution are found. The temperature decreases as altitude decreases air pressure: The amount of force pushing on a surface or area.-Think about how your ears feel under water…..image that higher up in the atmosphere….what might they feel like.
Low pressure
When air warms, its molecules scatter, the air becomes less dense and it rises. This causes low pressure. Air is usually cloudy and winds are particularly strong
High pressure
When air cools, its molecules move closer together, the air becomes more dense and it sinks. This causes high pressure. Weather is fair and winds typically light.
Radiation
The transfer of energy (including heat) through electromagnetic (light) waves. Examples include: radio, microwave, infrared, ultraviolet, visible light, x-rays, gamma rays
Ultraviolet rays
A form of energy given off by light with wavelengths that are shorter than visible light. Ultraviolet rays are harmful to living things
Wind
Horizontal movement of air from an area of high pressure to an area of lower pressure
