Science Test 2013-11-12

Question 1

What are Seismic Waves?

Answer 1

The waves that spread across the earth’s surface during an earthquake.

Wikipedia says:
Waves of energy that travel through the Earth’s layers during an earthquake, volcano…

Question 2

What is the earth’s crust?

Answer 2

The surface layer of the earth.

(<1% of the volume of the earth.)

Question 3

What is the earth’s mantle?

Answer 3

The layer of the earth just underneath the crust.

Question 4

What is the outer core of the earth?

Answer 4

The layer just deep to the mantle.

Question 5

What is the earth’s inner core

Answer 5

The part of the earth right in the middle;
It is deep to the outer core.

Question 6

What is the earth’s lithosphere?

Answer 6

The crust and the uppermost mantle layers.
These are hard layers of the earth.

Question 7

What is the Asthenosphere?

Answer 7

A part of the Upper Mantle just below the Lithosphere. Whereas the Lithosphere is hard,
the Asthenosphere is semi-molten.

The line dividing these two regions is 1300 degrees centegrade.

Question 8

What is heat?

Answer 8

Thermal energy.

Question 9

What is Conduction?

Answer 9

Spreading heat (in this case) by direct contact.

Question 10

What is convection?

Answer 10

Heat moves by flowing mantle / fluid?

Question 11

What is radiation?

Answer 11

Heat (or other energy) transferring with electromagnetic radiation (not with direct contact or with convection)

Question 12

What is Pangaea?

Answer 12

Pangaea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It was a single continent surrounded by ocean waters.

Question 13

What is Laurasia?

Answer 13

Laurasia was the northern breakoff of the Pangaea supercontinent.

Laurasia became what is now North America and Eurasia (Eurasia is the combination of Europe and Asia)

Question 14

What was Gondwana?

Answer 14

Gondwana was the southern portion of Pangaea

(after splitting from Laurasia)

Question 15

What is Sea-Floor Spreading?

Answer 15

Volcanic activity adds to oceanic crust.

This moves the crust and results |in the sea floor spreading apart.

Question 16

What are Ridges?

Answer 16

Underwater “mountain ranges” formed by volcanoes.

Question 17

What are Trenches?

Answer 17

An oceanic trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab.

Question 18

What is subduction?

Answer 18

One Lithospheric plate decending below another.

Question 19

What are plate tectonics?

Answer 19

Plate Tectonics is a scientific theory that describes the large-scale motions of Earth’s lithosphere. The lithosphere is broken up into 7 or 8 tectonic plates.

Question 20

What are Faults?

Answer 20

A fault is a planar fracture in rock, across which there has been significant displacement along the fractures as a result of earth movement.

Faults are where most earthquakes occur.

Question 21

What is a Transform Boundary?

Answer 21

Transform Boundaries are faults that neither create nor destroy lithosphere.

Relative motion is predominantly horizontal, end abruptly and are connected on both ends to other faults, ridges, or subduction zones.

Transform faults are the only type of strike-slip fault that can be classified as a plate boundary

Question 22

What is a Divergent Boundary?

Answer 22

It is a linear feature that exists between two tectonic plates that are moving away from each other.

Divergent boundaries within continents initially produce rifts which produce rift valleys.

Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges.

Divergent boundaries also form volcanic islands which occur when the plates move apart to produce gaps which molten lava rises to fill

Question 23

What is a Convergent Boundary?

Answer 23

In plate tectonics, a convergent boundary, also known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of lithosphere move toward one another and collide.

As a result of pressure, friction, and plate material melting in the mantle, earthquakes and volcanoes are common near convergent boundaries.

When two plates move towards one another, they form either a subduction zone or a continental collision.

Question 24

What is Direct Evidence?

Answer 24

Supports a claim without need for any additional evidence or scientific inferences.

Example: Touching lava is direct evidence it is hot, and while your healing from what are significant burns you can watch it cool to form rocks.

Question 25

What is Indirect Evidence?

Answer 25

It is evidence that relies on an inference to connect it to a fact.

Must accumulate into a collection of evidence before claims can more accurately by made.

Example: Indirect evidence of the layers of the Earth includes the varied densities of rocks and seismic waves.

Question 26

What are P-waves?

Answer 26

Primary waves (P-waves) are compressional waves that are longitudinal in nature.

P waves are pressure waves that travel faster than other waves through the earth to arrive at seismograph stations first hence the name “Primary”.

These waves can travel through any type of material, including solids and fluids, and can travel at nearly twice the speed of S waves.

In air, they take the form of sound waves, hence they travel at the speed of sound.

Typical speeds are 330 m/s in air, 1450 m/s in water and about 5000 m/s in granite.

Question 27

What are S-waves?

Answer 27

Secondary waves (S-waves) are shear waves that are transverse in nature.

These waves arrive at seismograph stations after the faster moving P waves during an earthquake and displace the ground perpendicular to the direction of propagation.

Depending on the propagational direction, the wave can take on different surface characteristics; for example, in the case of horizontally polarized S waves, the ground moves alternately to one side and then the other.

S waves can travel only through solids, as fluids (liquids and gases) do not support shear stresses.

S waves are slower than P waves, and speeds are typically around 60% of that of P waves in any given material.

Question 28

How do S and P waves support the theory that the earth has multiple layers?

Answer 28

Their travel characteristics differ because of how they propogate in the different types of layers.

Question 29

How are the earth’s layers sorted?

Answer 29

They are sorted by density. The densest layers are the deepest.