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Science Test Chap 4 Sections 1 & 2

Terms

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Pressure
Pressure is the force pushing on a surface or area. Gravity pulling on the rock causes the layers above to push on lower layers. This is the reason for the increase in pressure as you decend deeper into the earth.
Asthenosphere
The layer of the mantle just below the lithosphere is the asthenosphere (asthenes means "weak"). This layer is more malleable and softer than the lithosphere due to increased heat and pressure.
Convection Currents
Convection currents are the flow that is created due to this heat transfer. As a fluid is heated, it becomes less dense and rises. The cooler fluid (at the surface) is denser and sinks causing a current.
Earth's Magnetic Field
It is believed that metals in the core contain a weak charge. Convection currents in the liquid outer core force the inner core to spin faster than the rest of the planet. This current and spin produce a magnetic field which causes the Earth to act like a bar magnet.
Convection in Earth's Mantle
Earth's mantle responds to heat from the core. Hot columns of mantle rise through the asthenosphere and push cooler material out of the way. The cooler material sinks back down to the asthenosphere.
Indirect Evidence
Geologists must rely on indirect evidence to gather information about Earth's interior. One piece of evidence they use is seismic waves. Using speed and direction of the seismic waves gives geologists data that is used to describe Earth's layers.
Journey to the Center of the Earth
As you travel to the center of the Earth, temperature and pressure change.
Crust
The crust is the thin layer of solid rock that surrounds the Earth. It is thinnest under the ocean (mostly dense rock called basalt) and thickest under mountains (on the continents, mostly granite).
Radiation
The transfer of heat through empty space such as the sunlight or the flame of a campfire is an example of radiation. There is no direct contact with radiation.
Density
The amount of mass in a given space; mass per unit volume.
Conduction
The transfer of heat by direct contact.
Mantle
The mantle is the layer just below the crust starting at 5-40 km. The mantle becomes hotter and pressure increases as you descend through the mantle. The mantle is about 3,000 km. thick.
Core
The core is made up of two parts - the outer core & inner core. Iron and nickel make up both parts.
Seismic Wave
A vibration that travels through earth carrying the energy released during an earthquake
Earth's Interior- 4 parts
Crust, mantle, outer core, inner core
What is heat transfer?
The movement of heat. There are 3 ways - radiation, conduction, convection
What causes convection currents?
Differences of temperature and density within a fluid. They occur in the mantle.
Outer Core and Inner Core
The outer core is a thick liquid and the inner core is a dense ball of solid metal. The inner and outer core make up 1/3 of the Earth's mass (about 33%), but only 15% of its volume.
Convection
The transfer of heat through a heated fluid is convection.
Lithosphere
Includes the crust and the rigid, uppermost part of the mantle (litho means "stone") and this layer is about 100 km thick.

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