Final Exam 2 Flashcards
How do we know what the seafloor is like? Explain how man has been able to map the seafloor.
• Mapping the sea-floor was done almost by accident during WWI with the invention and use of sonar in submarines. Sonar has allowed us to map the seafloor.
How does the seafloor change as one travels from Atlantic coast of New England to the divergent plate boundary at the Mid Atlantic Ridge. Where would you find the coastal plain, continental shelf, continental slope, continental rise, abyssal plain, abyssal hills and rift valley?
- The sea-floor gets newer and newer as you go from the coast of New England to the divergent plate boundary at the Mid Atlantic Ridge.
- The coastal plane is located near the sea, it is a flat low-elevation area.
- Continental shelf is the piece of continent that is submerged under water.
- Abyssal Plain is essentially deep ocean where there is no continental landmass below the water.
- An oceanic trench is a very deep (deeper than the abyssal plain) drop off between the continental shelf and abyssal plain.
➢ Have portions of the continental shelf ever been exposed at the surface? If so, when might this occur and how might this change its surface? Does the continental shelf area have any economic importance? Please explain.
- Yes they have, during periods of glaciations where the sea level is low. This would change the surface by adding additional coastal regions.
- The continental shelf area has huge economic importance in mining oil.
Identify the type of mass movement of sediment which occurs along the continental slope and rise. What submarine features do they give rise to?
- The mass moving of sediment which occurs along the continental slope and rise is waves from the ocean which gives rise to beaches.
- The submarine feature they give rise to is coral reefs.
How do waves form? What factors would increase a waves’ height? Understand and be able to explain the following terms: wavelength, wave height, and wave period.
- Waves form from wind. Higher waves can be caused by higher wind speed, increased storm duration, and larger areas of wind.
- Wave length is the distance between crests
- Wave height is the vertical distance between crests and trough
- Period is the time between successive waves to pass
- It is also important to note that water moves faster on the top of the ocean than at the bottom (as depicted by the size of the arrows).
What causes breakers (breaking waves) in the surf zone? What is a long shore current? And how does it move sediment?
- The swash zone is an upper part of the beach where erosion occurs.
- Breaking waves are caused when a wave reaches certain height and cannot sustain itself, this generally occurs on the continental slope.
- The long shore current (long shore drift) is the direction in which sediment moves because of waves, it moves sediment through a swash backwash motion. Whatever angle the wave comes in at (generally due to wind) is the direction of long shore current.
What are rip currents and why are they dangerous to swimmers? What do you need to do to escape one?
• Rip Currents are excessive water moving back to the sea creating a circular flow of water. They are dangerous to swimmers because they don’t allow you to swim back on shore, to get out of a rift current you must swim along the shore (the same direction as the long shore drift).
Explain what causes ocean tides on earth. Why are tides higher at some locations?
• The moon’s gravity causes tides on earth, the water is literally pulled towards the gravity of the moon causing a high tide. Tides are higher at some locations because the pull from the moon changes relative to how close something is to it.
identify some erosional coastal landforms
Example: Sea stack, wave cut cliffs, sea arch
How do seasonal changes affect beach profiles? Man-made structures like groins, breakwaters, jetties are used to prevent beach erosion. In general what is there affect where there constructed? And the affect down-current (down coast) of the structures?
- Seasonal changes also effect the tides in the same way as the moon does. The sun’s position creates the seasons, although smaller, the sun has a gravitational pull that effects the tides. An example is the highest high tides will occur during the summer during a high tide, and the lowest low tides will occur during the fall during a low tide.
- In the area where these man-made structures are created they reduce the erosion and wave impact, however the affect down-current is amplified due to these structures.
What are glaciers?
River of ice that flows down a valley like a very slow moving river until it meets a sea or lake then it is considered an iceberg which is a piece of ice floating in water.
Describe the two main types of glaciers and the environment in which they form. Be able to recognize modern examples of each.
- Alpine glaciers – form on mountains
* Continental glaciers – form on continental land (such as Antartica)
How does the abundance of glacial ice affect sea level? Explain using the hydrologic cycle.
• As the amount of glacial ice increases sea level decreases, as glacial ice decreases sea level rises.
Ice ages have occurred (or are occurring) on earth during which geologic periods? What evidence supports this hypothesis?
• Ice ages occur during glacial periods. Glacial periods occur when temperature levels are low, this occurs when CO2 levels are low. CO2 levels can be calculated from rocks.
What factors are believed to cause ice ages (long-term causes)?
- CO2 levels
* Change in the eccentricity and tilt of the Earth’s orbit/axis
