earths mantle

heat flow

Scientists know that the mantle is extremely hot because of the heat flowing outward from it and because of its physical properties. Heat flows in two different ways within the Earth: 1. Conduction: Heat is transferred through rapid collisions of atoms, which can only happen if the material is solid. Heat flows from warmer to cooler places until all are the same temperature. The mantle is hot mostly because of heat conducted from the core. Peridotite is formed of crystals of olivine (green) and pyroxene (black). 2. Convection: If a material is able to move, even if it moves very slowly, convection currents can form. Convection in the mantle is the same as convection in a pot of water on a stove. Convection currents within Earths mantle form as material near the core heats up. As the core heats the bottom layer of mantle material, particles move more rapidly, decreasing its density and causing it to rise. The rising material begins the convection current. When the warm material reaches the surface, it spreads horizontally. The material cools because it is no longer near the core. It eventually becomes cool and dense enough to sink back down into the mantle. At the bottom of the mantle, the material travels horizontally and is heated by the core. It reaches the location where warm mantle material rises, and the mantle convection cell is complete (Figure 1.2). Convection.

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mantle

The two most important things about the mantle are: (1) it is made of solid rock, and (2) it is hot.

solid rock

Scientists know that the mantle is made of rock based on evidence from seismic waves, heat flow, and meteorites. The properties fit the ultramafic rock peridotite, which is made of the iron- and magnesium-rich silicate minerals (Figure 1.1). Peridotite is rarely found at Earths surface.

instructional diagrams

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questions

kimberlite pipes are amazing because they are

a) ancient, from when earth was younger and hotter.

b) the most important source of diamonds.

c) rock that comes from deep in the mantle.

-->  d) all of these.

scientists know that the mantle is made of the rock peridotite because

-->  a) of evidence from seismic waves, heat flow and meteorites.

b) it is commonly seen at earths surface.

c) it is ultrafelsic, which fits the density of the mantle.

d) all of the above.

heat that is transferred through rapid collision of atoms is conduction.

-->  a) true

b) false

in heat transfer, heat flows from a cooler place to a warmer place.

a) true

-->  b) false

scientists know that the mantle is extremely hot because heat flows out of it.

-->  a) true

b) false

put in order of how convection currents in the mantle move. i. the material that moved up cools and sinks back down into the mantle. ii. the bottom layer of the mantle material rises and spreads horizontally. iii. the mantle material near the core is heated. iv. the bottom layer of the mantle becomes less dense.

a) iv, iii, ii, i

-->  b) iii, iv, ii, i

c) i, ii, iii, iv

d) iii, i, iv, ii

this layer heats up the mantle.

a) crust

b) lithosphere

c) asthenosphere

-->  d) core

the temperature of material near the surface _ because _.

-->  a) cools; it is no longer being heated from below

b) cools; it comes into contact with rain, snow and ice.

c) warms; solar radiation.

d) warms; volcanic activity heats it up.

which of the following is not true about ultramafic rocks?

a) they are made of iron- and magnesium-rich silicate minerals.

b) they are denser than other rocks.

-->  c) basalt is the most common, since it makes up most of the mantle.

d) they are uncommon at earths surface.

peridotite is abundant at earths surface.

a) true

-->  b) false

diagram questions

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