2. Inlets often move or drift from one position to another (this is referred to as inlet migration). Take a moment to look at the inlets on either side of North Island.
a. Are they similar in size and shape? Why/Why not?
b. How have the inlets near these barrier islands migrated throughout the years? (Turn the layers of the different years on and off to compare).
c. Use your measurement tool to measure the distances from year to year.
c1. Is the rate of movement constant?
c2. Is the direction of movement constant?
d. Turn on the GPR (Ground Penetrating Radar) layer and click on the newly displayed line. Click on the hyperlink to view GPR imaging. Ground penetrating radar images layers in the ground. Do you see any patterns of layers? In what direction are the deeper layers inclined? what does this suggest about inlet migration and associated inlet channel migration?
e. turn on the "spit outline" layer over the 1994 layer. This layer highlights the spit growth of the southern end of North Island over the last 1000 years.
e1. Measure the length and width of the spit that has grown over the last 1000 years using the measurement tool. record these measurements on your paper.
e2. Now turn on the "core" layer to determine the thickness of the spit sediment.
e3. Using the above information, determine how much sediment has been deposited in the southern spit of North Island over the last 1000 years. Convert this rate to amount of sediment per year. If a dump truck holds 20 cubic meters of sand, how many dump trucks would it have taken to build the spit?
3. Shorelines move constantly. They are always being eroded, and sediment is always being deposited. Use your zoom tools in combination with the layer menu to determine if the shoreline of North Island has moved over time.
a. Use your measurement tool to determine how much or how little it has moved. Are there areas where little to no change has occurred? How could this variation affect one’s decision to build near the beach and where?
b. turn on the historical coastlines layer. How has the coastline of this barrier island chanded over the long term? What long term changes are involved in this historical coastal shaping.
4. Overwash deposits are prominent features of barrier islands. Very distinct overwash features can be found on North Island. (This island is the more Southern barrier island in your photo sets).
a. What do these features look like?
b. What processes may create these features, and how do you think these deposits affect the migration (movement) of the islands?
c. Measure and record the size of some of these features using the measurement tool.