Continental Drift and Plate Tectonics Virtual Lab, Summaries of Earth science

Download Continental Drift and Plate Tectonics Virtual Lab and more Summaries Earth science in PDF only on Docsity!

Continental Drift and Plate Tectonics Virtual Lab http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/t_tectonics.html

Directions: Click on the box shown to the left, then use that page to fill in the information to the right.

1. Watch the animation and use the arrows to click forward and back. mybp= million years before present. Click the arrows to move forward to 65 mybp. This is when the dinosaurs went extinct. Sketch the outline of the continents as they appeared when the dinosaurs went extinct.

Click forward to 0.05 mybp. What is the main difference you see on the map from 0.05 mybp to present day?

---

2. What is plate tectonics? The concept that describes and explains how the major features of the Earth _______________ and/or deform. The essential processes of plate tectonics are: A) ______________________________________________________________________________ B) ______________________________________________________________________________

Click on one of the larger color versions of the map. Notice the lighter areas, showing the underwater mountain ranges (mid-ocean ridges) of Earth.

3. How do scientists make detailed maps of the seafloor? They use variations of a method called “sonar.” Sonar involves _______________________________ , the same method used by bats to navigate at night. Click “GO.” Use the tabs at the bottom to click through the rest of the animation.

The Basics

1. Sonar Basics Sonar works by measuring the time it takes for sound to _____________________ off of a surface like the sea floor and return as an echo. The longer it takes for an echo to return, the farther ___________________ the reflective surface, whether it’s the far wall of a canyon or the sea floor.

2. The Actual Depth Sound waves travel at about __________ meters per second in seawater, so a _____ second round trip covers ~6,000 meters. However, the actual water depth is only half of that- 3,000 meters, because 4 seconds represents ________________ the one way distance to the sea floor.

3. What do you do with sonar data? After all the data are collected, processed, and _________________, scientists can now visualize the ________________________.

p. 114^ Feel free to click through the other tabs to learn more about different types of sonar technology.

What the Earth looked like in the distance past

Plate Tectonics

Imaging the shape of the sea floor

form

Seafloor spreading Subduction

echolocation

The main differences were that Oceana was farther south, Europe and Asia were more separated into continents and larger islands, and North America was much larger and more connected with Central and South America.

bounce

it takes for

330 330

4. Study the animation. How fast are the plates moving apart?___________________________________ Add arrows to the diagram below to show how the tectonic plates are moving.

Key Points A) Seafloor spreading takes place at mid-ocean ridges and produces ______________________, the rock that makes up oceanic crust.

B) The _______________________________ Ridge and East ________________________ Rise are examples of mid-ocean ridges.

C) Mid-ocean ridges reach a typical summit of __________ meters below sea level. D) Seafloor spreading produces major characteristics of the seafloor:

1. The age of the seafloor is progressively ____________________ away from mid-ocean ridges.

2. The elevation of the seafloor is progressively lower away from mid-ocean ridges.

3. The magnetic history of the seafloor bears the ____________________ pattern of the Earth’s magnetic reversals.

4. _________________________ parts of the seafloor have the greatest potential to have accumulated sediments over the longest time.

5. Study the animation. Turn the labels on and read them.

Key Points A) Subduction is a geological process in which the edge of a lithospheric plate slides ______________________ the edge of an adjacent plate.

B) Trenches, accretionary wedges (prisms), and volcanic or _________________ arcs are key surface features produced by subduction.

C) A subduction zone is the entire ________________ of subduction between the trench and the volcanic arc.

D) The __________________________ marks the line where subduction begins.

E) What is an accretionary wedge?

---

---

p. 115

Seafloor spreading (Key Process #1)

Subduction (Key Process #2)

The plates are moving apart very gradually.

basalt

Mid-Atlantic Pacific

2,

older

striped-

Older

underneath island

area

trench

Accretionary wedges are prisms.