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Longitude and meridians

Island Ages of the Hawaiian Archipelago.


Study the tectonic map of a hypothetical ocean basin (page 6 of this packet). The map shows the location of volcanoes, earthquakes, and the age of ocean floor rocks. From this map, you will determine the probable location of the plate boundaries and the locations of major topographic features in the region.

The edges of two continents are shown (in the upper right corner and lower left corner). Six islands are also shown. The symbols used on the tectonic map are described below.

Earthquake Epicenter Location and Depth:

The locations of earthquake epicenters are shown with letters. The depth of the earthquake (the distance of the earthquake hypocenter or “focus” below the surface) is indicated with an “S” (shallow focus), “I” (intermediate focus), or “D” (deep focus):

S = Shallow Earthquakes 0-70 kilometers (0-45 miles) deep

I = Intermediate Earthquakes 70-200 kilometers (45-125 miles) deep

D = Deep Earthquakes 200-500 kilometers (125-310 miles) deep

Active Volcano: 

Continent or Island: 

Activity Procedure:

The first step of the activity is to draw in the approximate plate boundaries as indicated by the tectonic activity on the map.

Clues include:

a) The pattern of earthquakes. For example, subduction produces a pattern of deeper and deeper earthquakes as one plate plunges below the other.

b) The age pattern of volcanic ocean floor rocks suggests the location where new ocean floor is being created at a midocean ridge.

c) Volcanic activity may be associated with subduction, spreading centers, or hot spots.

Use the following symbols to indicate the extent of all plate boundaries. Both the map symbols, and a side view of the circumstance they represent, are shown below. Arrows indicate direction of plate movement.

Convergent Boundary (Subduction) Divergent Boundary

Map symbol to be used: Map symbol to be used: