Science - Chapter 25 Review (Trivia)

Provide 4 pieces of evidence Wegener used to support Continental Drift.

1. Fossils of land animals and freshwater reptiles found in areas separated by ocean.

2. Similar rock formations found on either side of the Atlantic Ocean

3. Fern fossil (glossopteris) found in areas of different climates

4. Matching coastlines (puzzle-like fit of the continents)

5. Evidence of glaciers found in warmer areas

What type of plate boundary would produce a volcanic island arc? 

Oceanic-oceanic convergent boundary

What are two pieces of evidence for seafloor spreading discovered by studying properties of the Atlantic seafloor?

1. Younger rock is found near the mid-ocean ridge which means rock must be forming there and spreading outward

2. Symmetrical record of magnetic polarity on either side of the mid-ocean ridge

Explain what happens at a oceanic-continental convergent boundary.  Where on earth can we find an example?

Oceanic plate will subduct beneath the continental plate because it is MORE dense. The subducting plate will melt and magma will rise through the crust to form a chain of volcanic mountains. Ex. on Earth: Andes Mountains in South America

If the Pacific Plate is moving at about 10 cm/yr, how many years will it take to move 5 feet? (There are 30 cm in a foot)

15 years

Name two features that would form at an oceanic-oceanic convergent boundary.

1. Volcanic island arc

2. Deep sea trenc

Explain how a subduction zone forms.

When a more dense plate sinks beneath a less dense plate and melts back into the mantle.

Which type of convergent boundary does not produce a subduction zone? And name a location on earth!

Continental-continental convergent boundaries. Ex. on Earth: Himalayan Mountains (Mt. Everest)

How did the mid atlantic ocean ridge form?

When two oceanic plates diverge (spread apart) and magma rise to fill the gap and cools to form new oceanic crust.

Name a feature on Earth that has formed from:

1. Oceanic-oceanic Convergence

2. Oceanic-continental Convergence

1. Mt. Fuji (Japan)

2. Andes Mountains (South America)

Describe how the islands of Hawaii formed.

A hot spot in the mantle causes magma to rise up through the Pacific Plate to form a volcanic island. As the plate moves above the stationary hot spot, a chain of volcanic islands forms over time.

What is the difference between stress and strain on crustal rocks?

Stress is the force that is placed on crustal rocks (three types: compression, tension, shear).

Strain is the result (change) on the rock due to the stress (two types: elastic and plastic deformation)

A oceanic crustal rock has a density of 3.2 g/cm³ and a mass of 285g, what is its volume?

Volume = mass / density

Volume = 285 / 3.2 = 89.063 cm³

Explain how convection currents transfer thermal energy. Include density in your answer! 

Warm material rises because it is less dense, while cooler material sinks because it is more dense.

What provides the heat for the driving forces of convection in the lower mantle?

Radioactive decay (breakdown) of metals in the outer core is releasing heat in the lower mantle, which drives convection currents

How do we know that the outer core is liquid? 

S-waves cannot travel through liquid, and we know they disappear in the outer core. Therefore, we can infer that the outer core is liquid.

List 2 differences between P and S waves.

P-waves are faster than S-waves

P-waves push and pull rocks (compression waves) while S-waves move rocks up and down (transverse waves)

P-waves can travel through solids and liquids, while S-waves can only travel through solids

Two numbers up on the Richter scale corresponds to how much more energy released by an earthquake? (Ex. from a 4 to a 6)

100 times more energy

Explain the process that seismologists use to locate an EQ epicenter.

Seismologists gather the difference in time between P and S waves from 3 seismic stations after an earthquake.

A time-travel curve can be used to find the epicenter distance from each seismic station based on the wave time difference.

A circle is drawn around each seismic station with a radius equal to the epicenter distance.

Where all 3 circles intersect is the location of the epicenter

Why can we only study seafloor from 200 million years ago and younger?

Because ocean crust will subduct and melt (disappear) once it is pushed into a continent, so crust older than 200 million years does not exist anymore.