Portland State University Oceanography Google Earth and Plate Tectonics Questions

IMPORTANT

………….READ THIS first:

This exercise uses

Google Earth

(http://www.google.com/earth/index.html ) and Google

Earth overlays (.kmz files created by various members of the scientific community) and

information from the USGS website including seismic data and maps.

To import these

files into Google Earth, simply pick them up with the cursor and drop them into Google

Earth.

You can activate/deactivate the individual layers in the “Temporary Places”

folder located on the panel on the left.

FIRST and FOREMOST: Download Google Earth:

https://www.google.com/earth/download/gep/agree.ht…

Never used Google Earth Before? Perhaps try a Google Earth Tutorials:

1. Go to:

http://www.google.com/earth/learn/beginner.html

and select the

Navigation

and

Drawing and Measuring

tours to familiarize yourself with

basic navigation in Google Earth.

Updating program if you already have Google Earth on your computer:

Since Google earth often has updates, please do the following steps prior to starting the

lab

1.

Open Google Earth on the laptop. Go to “help” and select “check for updates online

and

update if available or go to “

http://www.google.com/intl/en/earth/index.html

“

for the update.

2.

Please

uncheck the box

for: “Include Google Chrome, a fast new browser for

Windows and

Mac”.

Then select “agree and download”

DELIVERABLES

:For this lab, you will need to record your answers in a separate word

document.

ONLY PROVIDE THE ANSWERS FOR THESE QUESTIONS IN THE DOCUMENT

YOU TURN IN.

You should include your name on the first line of the document and the

second line should read:

Lab 1 Introduction to google earth and Plate Tectonics.

Number each of your answers according to the question in this document. Each answer

must be on a different line.

Exercise 1: Latitude and Longitude

Turn on the latitude and longitude grid. Go to “View” from the top menu and select

“grid”.

Look at the very bottom of your screen. The Latitude, Longitude and elevation of your

cursor are shown. Negative elevation is depth below sea level.

(You can change from the units from decimal degrees to degrees, minutes, and seconds, AND from

meters

to

feet

by going to “Google Earth” from the top menu, then “Preferences”.)

1.

Locate 0

o

Longitude. What is the name of this line? __________________________

2.

Locate 180

o

Longitude. This line is called the International Date Line or the

_________________.

3.

While looking at 180

o

Longitude, what general direction are the Hawaiian Islands

located (east or west direction) of this line ? _________________

4.

Search for Mauna Kea (use the search box) and zoom in until you get a blue/grey

square. Place your cursor over the center of it. What is the Latitude and

Longitude (degrees and minutes only) of Mauna Kea in Hawaii?

Lat____________________ Long_____________________

5.

What is the Lat/ Long (degrees and minutes only) of the Loihi seamount?

Lat____________________ Long_____________________

6.

What is the depth of the seamount (in meters)? ____________________

7.

Briefly describe the significance of Loihi with respect to the Hawaiian Islands.

Exercise 2: Measuring Distances



Using the ruler (available along the toolbar at the top as the ruler icon), set the

distance units to Kilometers and measure the following with the ruler in Google Earth:

8. Approximately how far is Mauna Kea from Loihi seamount (in km)? _____________

9. Search and proceed to the island of Guam. What major deep ocean basin feature is

directly east of Guam? You may need to zoom out a bit in order to get some

perspective.



Now zoom out and head to Florida!

10. Using the ruler tool, how far from Florida’s east coast is the Mid Atlantic Ridge?

________

Exercise 4: Plate Tectonics

Plate Boundaries

– Recall: there are 3 basic types of plate boundaries:



Convergent

– When plates come together, one plate will be subducted under the

other. This forms features such as mountains, island arc systems, and ocean trenches.

Continent – Continent

– These often form mountain ranges.

Continent- Oceanic

– The denser oceanic plate subducts under the less dense

continental plate.

Oceanic-Oceanic

– The older and denser oceanic plate will subduct under the younger

less dense oceanic plate.

Divergent

– When plates move apart it creates spreading centers that show up as sea

floor spreading zones in oceanic crust, and rift valleys in continental crust.

Transform

– When plates slide past each other. They are very common in oceans

where they offset mid-ocean ridge. Now go back to Google Earth!

DRAG and DROP the “

Earths_Tectonic_Plates.kmz” file onto Google Earth

. You

should now be able to see the location and nature of the plate boundaries.

11. What is the main plate boundary type found at the Mid-Atlantic Ridge?

12. What type of boundary is found between the South American Plate and the Nazca

Plate?

13. What type of plate boundary runs through California?

14. What type of present-day collision formed the Himalayan Mountains at the

boundary between the Indian Plate and the Eurasian Plate?

Now, DRAG AND DROP “seafloor_age_10my_isochrons.kmz” into Google Earth

15. What is the approximate age of the crust at the Mid Atlantic Ridge plate boundary?

16. What is the approximate age of the oceanic crust off the eastern seaboard of North

America?

17. Proceed to the oceanic crust off the coast of Oregon. What is the age of the crust

just offshore?

18. Why is the crust so young off the coast of the Pacific Northwest?

19.

Look at the divergent plate boundary in the south Pacific west of South America.

How wide (east to west) is the 0 -10 Ma crust along this plate boundary?

(use the

ruler tool)

20. How wide is the 0 – 10 Ma crust along the Mid Atlantic Ridge?

21. Why is there is such a dramatic differences between the widths of the youngest

crust along these two mid ocean ridges?

22. Now, zoom back over to the Mid Atlantic Ridge. Describe how ocean depth

changes as you go from the Mid Atlantic Ridge plate boundary east toward the coast of

Europe. Give specific depths.

23. If you start at the Mid Atlantic Ridge and Move WEST toward North America, do you

observe the same pattern of depth variation?

You can now deactivate the “seafloor_age_10my_isochrons.kmz” layer. To do

this, click the box next to that layer, on the left under “Places”

Now, go to the island of Tonga (if you don’t know where this is, type “Tonga” into the

search bar.)

READ THIS:

Make sure you have a distance scale at the bottom left. If you don’t, go to

“VIEW” at the top of the screen, and click “Scale Legend” and it should appear. You’ll

want kilometers instead of miles, so again at the top, click on “Google Earth” >

”Preferences” and then find “Units of Measurement” and select “meters, kilometers”.

Ok, Tonga is an island that sits near a convergent a plate boundary (

disregard the

divergent plate boundary labeled here-the red line).

Make sure you are properly

zoomed out (field of view of the screen at ~1500km or so).

24. Describe how the ocean depth changes as you approach and cross the Tonga plate

boundary from ~500 km east of Tonga to ~250 km west. Give specific depths.

25. What specific plate tectonic feature did you just cross