Lecture 14

Question 1

What are the major zones of the earth?

Answer 1

• Crust
• Mantle
• Core

Question 2

Mineral

Answer 2

A naturally occuring, inorganic, element or compound, with a definite internal arrangement of ions(solid) and a chemical composition that is fixed or varies within narrow limits.

Question 3

Rock

Answer 3

Aggregates of one or more minerals, found on earth’s crust.

Question 4

What is the most abundant mineral in earth’s crust?

Answer 4

Oxygen

Question 5

How can oxygen be part of the crust?

Answer 5

Very reactive, so reacts with other elements

Question 6

Native elements

Answer 6

Pure elements

Question 7

What are the most abundant mineral groups?

Answer 7

Silicates

Question 8

When is the chemical make up of minerals more common?

Answer 8

In ion substitution

Question 9

What are the ways to identify minerals?

Answer 9

• Hardness
• Color, luster, streak
• Density
• Cleavage/fracture
• Magnetic properties

Question 10

silica tetrahedron

Answer 10

Silicon atom attached to four oxygen atoms by tetrahedral bonds, results in a 4- charge on the SiO4 (silicate) group. Basic building block of silicates.

Question 11

Pyroxenes

Answer 11

Single chains of tetrahedra balanced by similar metal cations and sodium(Na)

Question 12

Amphiboles

Answer 12

Double chains of tetrahedra balanced by similar cations.

Question 13

Micas and Clay materials

Answer 13

Sheets of tetrahedra are the building blocks. Aluminum is also involved in these sheet structures which are charge balanced by the cations Mg, Na and K

Question 14

Feldspars

Answer 14

A second group of alumino-silicates, the tetrahedra form three-dimensional frameworks with Ca, Na and K as the balancing cations.

Question 15

Quartz

Answer 15

Three dimensional framework structure without cations an just silica tetrahedra. Very stable

Question 16

What are mineraloids?

Answer 16

Not minerals include Opal and amber

Question 17

How are minerals formed?

Answer 17

Formed by crystallization. The center of the earth causes rocks to melt forming magma. When magma cools various elements and ions come together to form very specific structure. Different minerals form at different temperatures.

Question 18

What are the three categories of rocks?

Answer 18

Igneous, Sedimentary and Metamorphic

Question 19

Igneous rock

Answer 19

formed by the crystilization of magma. Two forms:

1) Extrusive(volcanic)-rapid cooling, usually derived from upper mantle high quantities of iron and magnesium
2) Intrusive(plutonic)-slowly cooling, usually derived from crust so relatively rich in silicates and aluminum.

Question 20

Sedimentary rock

Answer 20

formed by the sedimentation and campaction of material(lithification)
-tends to form in layers

Question 21

Metamorphic rock

Answer 21

Rock that has been chemically altered while in the solid state from exposure to high temperatures and pressures. The process is re-crystallization

Question 22

Rock cycle

Answer 22

Goes from igneous to sedimentary to metamorphic and back to igneous. Look at slide photo

Question 23

What are the parts of the earth’s core?

Answer 23

inner (solid) core

outer (liquid) core

Question 24

Seismograph

Answer 24

Measures and records the minute tremors of the earth

Question 25

How have the properties of the inner earth been analyzed?

Answer 25

Looking at meteorites(similar in composition to earth) and the seismograph

Question 26

What are the two waves propogated by the earth?

Answer 26

Surface waves(travel along the surface) and Body Waves(travel on earth interior)

Question 27

What are the forms of body waves?

Answer 27

P-waves and S-waves

Question 28

P-waves(primary waves)

Answer 28

compression waves like sound waves

Question 29

S-waves(secondary or shear waves)

Answer 29

Involve displacement perpendicular to the direction of the wave.

Question 30

What body wave type is fastest?

Answer 30

P-waves

Question 31

The S Shadow

Answer 31

S-waves do not propogate through the liquid outer core. Since S-waves only travel through solid material, it has been concluded that the outer core must be composed of molten metals.

Question 32

Does the earth interior have an effect on wave velocity?

Answer 32

Yes, changes in the properties of the earth interior with depth cause the waves to bend.

Question 33

lithosphere

Answer 33

composes the first 70-125km of the solid earth, consists of the oceanic and continental crustal material plus the uppermost portion of the mantle. It is rigid and acts as a single unit.

Question 34

asthenosphere

Answer 34

(~100km in depth) characterized by low p-wave velocities. Because of low velocities geologists have deduced that the layer is plastic(not liquid or solid) as a result provides.

• source of material ejected in volcanoes
• rebound of crust following ice ages
• provides malleable layer upon which plates can flow