GS 195 Mapping the World Exercise 5Tectonic and Coastline mapping

Background materialA. Read the Open Source chapter on Understanding Plate Motions.B. Go through the slideshow on the website

http://webgeology.alfaweb.no/webgeology_files/english/plate_tect_v2.swfC. Read the description of the USGS Geological Mapping of the Massachusetts Sea Floor

program on the website https://woodshole.er.usgs.gov/project-pages/coastal_mass/

In this activity, you will use a software package called GeoMapApp to investigate elements of plate tectonics across the Earth. You will examine the configuration of the North Atlantic. Then you will take a detailed look at the Massachusetts coast and changes due to sea level rise.You will answer the numbered questions in Part 1 and Part 2 and put the answers in a word document. Also insert into the document the images that you capture while doing the exercise.

Go to the GeoMapApp homepage (http://www.geomapapp.org). Use the Click here link to launch version 3.6 of GeoMapApp Allow the Java installation to proceed if needed

When the download is complete, Click OK to open the default Mercator Base Map. Once GeoMapApp is running, you'll see a map image of Earth.

Investigating Earthquakes Click on the “Portals” menu, and then choose “Earthquake locations, Epicenter Depths, and

Magnitudes”. Use the menu File -> Save Map Window as Image Grid File to create a jpeg of the map to

include in your write-up.

1. Where are three locations where you observe deep earthquakes (> 250 km)? Be specific, i.e., East Coast of North America.

2. Do these locations have anything in common as far as tectonic setting? Explain your answer.

You should refer to the geology tectonics lecture, which shows the plate boundaries.

3. Are there any plate boundaries that are characterized only by shallow earthquakes no deep earthquakes? If so, what sort of plate boundary is it?

Zoom in the North Atlantic using the Zoom toolbar button , so that you have a map view similar to the one below on your screen.

You will draw a cross-sectional profile from A-A’ using the Distance/Profile toolbar button.

click on the Distance/Profile tool at the top of the screen:

You may need to patiently wait while GeoMapApp opens the profiling tool. When the program is ready, refer to the world map pictured in this exercise.

To draw the A-A’ line in GeoMapApp, place your cursor in the appropriate location in Massachusetts (A). Click at the location with the left button and drag the cursor across the Atlantic Ocean to Spain, release the button.

When you first do this, the line might be drawn as a great circle. In the profile tool, click the box specifying that you would like to draw the cross section along a

straight line:

Click the Save menu on the profile to save the image to your computer as a JPG image. Dismiss the profile. Zoom in to the east coast of the US to Massachusetts and the Continental Shelf as shown

below.

Create a profile for this section A – A’. Save the resulting Graphic. 4. Examine the variation in elevation above and below sea level on your two profiles.

a. Explain the cross section of the Atlantic Ocean in terms of its tectonic setting and history.

b. Discuss the configuration of the Massachusetts coast; how are they related to the long term geologic history of North America and the recent glacial period.

Part 2 Coastline Change in Massachusetts

Coastal change mapping using Online GIS

This is an Online exercise using the State of Massachusetts Coastal Zone Mapper Application. You run the exercise in a browser window, it should work under whatever browser application you use.

In the internet browser, go to http://www.mass.gov/mgis/mapping.htm

Click the Link Shoreline Change under Quick Links.

Click the Link CZM Massachusetts Shoreline Change Project

A new browser Window opens up, this is basically a disclaimer page, you must click on the link at the bottom, Shoreline Change Fact Sheet before the application will run.

Read the Fact Sheet and answer the following

1. What data is used in the application?

2. What potential impacts are there from coastal erosion?

3. What impacts do anthropogenic structures have on erosion?

When you have your answers and are ready to look at the Map, click YES under I have read the factsheet and want to proceed.

Under ‘Available data layers’ double click ‘Physical marine and estuarine data’. Double click ‘Tidal currents greater than 3 knots’.

Click the link Launch MORIS Shoreline Change Map.

In the search box at the top of the map type ‘duxbury beach, MA ‘ and press enter. Select ‘zoom to region’ in the dialogue box.

Using the zoom scale on the left of the screen to zoom in to bridge that connects the mainland to the Duxbury peninsula

Zoom until the scale is between 1:15,000 and 1:20,000.

Click the ‘measure’ button on the bottom left of the screen and select ‘units’ click ‘nautical miles’.

Measure the length of the narrow bridge, place your cursor on one side and click, move it to the other and click again.

4. What is the length of the bridge in meters?

Zoom in to the Parking Lot on the seaward side of the bridge, zoom in to a scale of about 1:6000.

At this scale the Transects should appear. The transects are orange lines perpendicular to the shoreline, they are identified by transect number and the change in meters of the shoreline on average for the time period of the data. You will examine the transects and look at changes over the given intervals.

Click on the tool, Identify Features by drawing a box.

Click and drag a box to select the transects from 8020 to 8030 (an Orange Rectangle appears as below).

In the Query Results box, click on the Shoreline Change Transects layer

A table of attributes for the selected transects open

This table shows the rates of change for the different time periods. You will examine the data from the beach fronting the parking lot. It has been extracted for you and is on Blackboard as an Excel file - Duxbury Shoreline Change.

The file contains the following fields

TRANSECTNO – Transect NumberERA01 - Time period of Interval (ERA) number 1ERA01RATE – Shoreline change rate for Interval 1 ERA02 - Time period of Interval (ERA) number 2ERA02RATE - Shoreline change rate for Interval 2ERA03 - Time period of Interval (ERA) number 3ERA03RATE - Shoreline change rate for Interval 3

5. Examine the File and the map of the Transects on the following page and describe the change in the rate of erosion for the time periods and the location of the transects which run from 200 meters north of the parking lot to 200 meters south. What differences are there? The parking lot was built in the 1930s, did the rate of erosion in this area change after this?

Zoom out to a scale of about 1:120,000, you should be able to see the entire peninsula.

At the top of the image is the Blackwater Inlet, use the zoom-in tool and pan tool to find the Inlet

6. Examine the transects from either side of the inlet and work your way down the coast. Does the amount of development behind the beach seem to impact the rate of erosion? Give specific examples to support your conclusion.