Lab Activity 1.3
Geological Provinces

  Directions

Study the instructional material below. Be sure to click on each of the photographs for an enlarged view in a separate window. The larger version is necessary to complete the assignment. It opens in a separate window which can be resized by grabbing the bottom right corner and dragging it. It can also be moved by grabbing the top heading bar and dragging it. Be sure to close the extra window by using the X in IBM, or the close box in MAC when you are finished using them.

  Introduction


The sea floor can be divided into the continental margins and deep ocean basins. A continental margin is just the submerged edge of a continent but an ocean basin represents the floor of the ocean itself. The global processes of plate tectonics have produced the major features of the sea floor. These features are quite similar from place to place and can be easily characterized and described.

Top  Instruction

Study the information and the diagrams of the geological provinces of the ocean depicted below. Learn the various undersea features and their orgins.

Be sure to write about what you are learning in the lab section of your notebook. You will be expected to answer questions about the lab activity during the lab self test and lab quiz. It helps to have your text and coloring books open beside you for support.

 
Supporting Information
Refer to the Assigned Readings Below:
Marine Biology Textbook Chapter 2, pages 35 to 39
Marine Biology Coloring Book None
 
Continental Shelf

  1. Continuation of the continent under water
  2. Slopes gently seaward
  3. Generally less than 130 meters deep and 65 miles wide on average
 

Continental Slope
  1. The break between the continent and the ocean basin
  2. A 4 to 5 degree slope that marks the seaward extent of a continent
  

Continental Rise
  1. A ridge of sediment parallel to the continental shelf and seaward of the continental slope
  2. Rises are found only along passive continental margins such as the east coast of the United States
  

Abyssal Plains

  1. Broad, relatively flat areas of sea floor
  2. At depths of from 4,000 to over 5,000 meters
  3. Located adjacent to passive continental margins
  4. Located around the edges of most oceans

Ridges

  1. Mountainous systems with many volcanoes that extend for thousands of miles
  2. Often in mid-ocean but some are near continents
  3. Associated with divergent plate boundaries (spreading centers)
  4. Mountains closest to the spreading center where they are created by volcanism are the tallest and those further away have cooled, shrunk, and sunk.
 Fracture Zones

  1. Large cracks in the sea floor that may extend for thousands of miles
  2. Associated with ridge systems running perpendicular to the ridge
  3. Also associated with shearing (transform) plate boundaries
  4. May offset continental margins

Trenches

  1. Long, very deep depressions in the sea floor formed by subduction (movement of one crustal plate under another)
  2. There are 31 trenches with bottoms lying from 4.5 to 6 miles below the ocean surface
  3. Associated with convergent plate boundaries (subduction zones)

Seamounts

  1. Mountains that rise from the basin floor reaching heights of thousands of meters
  2. They often occur in groups or chains
  3. They may break the ocean surface to form islands
  4. Associated with plate boundaries or hot spots


Lab Activity 1.4 The Sea Floor