Please answer A through D regarding figures below which show bathymetric maps of

Question

Please answer A through D regarding figures below which show bathymetric maps of parts of the East Pacific Rise and Mid-Atlantic Ridge at the same scale.

A) Ocean ridges typically hae a rift valley at their axes--a valley created when two continents split. Which of the two ridges in the previous figures has the deepest and kongest rift valley?

Different spreading rates cause variations in shape because of the way the cooling lithosophere behaves. Lithosphere near the ridge axis is young, thin, still hot, and therefore has a lower density than older, colder lithosophere far from the axis. As a result, the ridge axis area floats relatively high on the underlying asthenosphere, and the water above it is relatively shallow. As seafloor spreading movves the oceanic lithosphere away from the ridge axis, the rocks cool and get thicker and denser. THe farther it is from the ridge axis, the lower the oceanic lithosophere sits on the asthenosophere and the deeper the water will be. This concept is known as the age-versus-depth relationship.

B) Keeping in mind the age-versus-depth relationship, why is the belt of shallow sea wider over the East Pacific Rise than over the Mid-Atlantic Ridge?

C) On the graph below, plot depth (on the vertical axis) against the distance from the ridge asxis (on the horizontal axis) for both the East PAcific Rise and the Mid-Atlantic Ridge. Use five to ten points for each ridge, marking the points you use on the maps on page 38. Connec the dots for the East PAcific Rise with red pencil and those for the Mid-Atlantic Ridge with green pencil to make cross sections of each ridge.

D) Does the rate at which the depth increases with distance from the ridge stay the same over time, decrease over time, or increase over time?

A Tale of Two Ridges EXERCISE 2.7 Section: Name: Course: Date: The figures below show bathymetric maps of p arts of the East Pacific Rise and Mid-Atlantic Ridge at the same scale 500 km (a) The East Pacific Rise in the South Pacific Ocean 500 km (b) The Mid-Atlantic Ridge off South America. (continued)

Explanation / Answer

A. The deepest and longest ridgeis the mid atlantic ridge . This is because it has a different spreading rate than pacific ocean and also different cooling rate of the lithosphere,spreading takes place when the hot magma comes from below so the ridge axis is formed and magma comes out of it.when the lithosphere moves away from the ridge the cooling takes place and as the moves more away from ridge axis more deeper and cooler it will be.

B. These is because the east pacific is a rise not a ridge. usually ridges have a grater slope and hence more steeper so magma flow will be also steeper but since in pacific it is a rise whose slope is lesser so the magma spreads away LESS in comparatively with mid atalantic.

C. the images are not clear and the question is not cmplete in the image.

D.The depth increases with time because at the ridge axis the density is low and as it moves away the density becomes high and hence it subsisides bathymatically as it move away from from ridge axis or older. BATHYMETRIC DEPTH IS DIRECT RELATED TO SQUARE ROOT OF TEMPERATURE. D = 2.6+0.36T1/2

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