Oceanography Week 5

16. What is meant by "marine snow"

a. "Marine snow" is white deep-sea ooze that has been moved up by geological procresses and can now be seen on land. It is calcium carbonate that accumulated above the CCD and is now visible on places such as mountain tops.

4. What is meant by the term "ooze" and what are the two types of "ooze"

a. "Ooze" any sediment that is more than 30% biogenous, that is to say, from plant or animal matter. Two kinds of "ooze" arecalcareous ooze and siliceous ooze.

29. How much rise in sealevel do they suggest will occur in the next 90 years

a. Scientists believe that the sea levels will rise more than 3ft in the next 90 years.

13. What sediments accumulate most rapidly, Least rapidly

a. Terrigenous sediment accumulates the most rapidly and cosmogenic sediment accumulates the least rapidly.

21. What happened in the Java Trench to produce the 2004 tsunami

a. A rupture ripped along the Java Trench for 8 minutes, for a distance about the length of both California and Oregon. One one side, the sea floor moved down, on the other side, the sea floor moved up. The water bounced between them, making a chain reaction and forming "gravity waves," like enormous ripples in a pond. They were 300 miles apart.

27. What is a storm surge - how big was the storm surge associated with Katrina

a. A storm surge iswhat happens when the sea rises in an enormous swell, due to the strong winds of a storm. Katrina's storm surge was an enormous 27.8 feet.

12. Why are some areas of the seabed altogether free of overlying sediments

a. All ocean water has sediments, but there are some very rare areas where for some reason the sediment cannot settle on the bottom. Some reasons for these rare areas could be strong currents that carry away the sediment before it has time to settle, hot water that dissolves the sediment before it can settle, or just the youth of the area hasn't permitted it time to collect any sediment yet.

14. What is a microtektite

a. Amicrotektite is a translucent particle of glass that came from space. They are believed to be formed in the violent impacts of meteors or asteroids hitting Earth. The crustal material on the meteor or asteroid melts from the heat of the impact and melts again when it comes through the atmosphere. This explains their shapes, which are oblong to spherical.

24. How is the ACC different from all other ocean currents in the world

a. Antarctic Circumpolar Current is one of the world's deadliest currents. It is the only place in the world where water can move unimpeded - there are no landmasses to block it. It moves about 2.25 mph - slow, but massive.

25. Why does the current flow so fast around Cape Horn

a. At the pinch point between South America and Antarctica, the ACC is squeezed into a chokehold, causing it to burst forth like several fire hoses.

18. Why are Atlantic sediments generally thicker than Pacific sediments

a. Atlantic sediments are generally thicker than Pacific sediments because most of the sediment deposited into the Pacific ocean cannot reach much further than its continental shelves. The sediment is trapped in the peripheral trenches and does not reach the deep ocean basin.

15. What are the sources of the two types of ooze

a. Calcareous ooze is from carbon-containing material, such as the shells of foraminifera, mulluscs called pteropods, and algae called coccolithophores. Siliceous ooze comes from silicon-containing material, such as the hard parts of radiolarians and algae called diatoms.

2. What are the four (4) main types of ocean sediment

a. Classic/terrigenous: from particles of rocks and minerals b. Hydrogenous: from water c. Cosmogenic: from space d. Biogenic: from plants and animals

30. What future problems do they suggest will occur in the oceans

a. Future problems with the ocean could include increased flooding, more intense hurricans and storm surgers (the rising temperatures will provide futher "fuel"), and the absorbption of CO2, pesticides, and other pollution.

28. Where do icebergs come from

a. Icebergs come from glaciers, which are made of compacted snow. Glaciers accumulate on land and then crumble off into the ocean. These floating pieces of glaciers are called icebergs.

6. How are temperature and pressure related to the CCD

a. Lower temperatures and higher presure both promote higher dissolution of carbonate sediments. The CCD is drawn at the point where it is so cold and high pressure that carbonate sediments cannot exist in the water any longer.

20. How might past climate be inferred from studies of marine sediment

a. Marine sediments can reveal information about past climate through measuring isotopes of oxygen in carbonate shells found in deep-sea sediment - telling us about changes in water and air temperature as well as volume of ice. There is other evidence in those microfossils that can tell us about ocean circulation, the marine biosphere, and upwelling, in order to fill in our picture of ancient climates. Stratigraphy can also give us information on climate.

8. What is a methane hydrate and why are they important

a. Methane hydrates are formed by the anaerobic decomposition of sediment. When combined with water, they can make crystals. They are important because they are a large source of carbon dioxide. Fluctuations in climate could make that ice melt, causing that carbon dioxide to be released into the atmosphere and further exacerbate climate change. Methane hydrates can also serve as records of past carbon dioxide levels.

5. Where does most of the "dust" come from that is deposited in the oceans

a. Most of the "dust" that is deposited by wind into the oceans comes from arid regions, such as Africa.

11. Contrast Neritic and Pelagic sediment.

a. Neritic sediment is mainly terrigenous and accumulates around the coast of continents. Pelagic sediment is found in the deep sea and is largely biogenous. Pelagic sediment is also much finer (smaller) than neritic.

9. What does it mean if we say a sand sample is compositionally mature

a. Sand is compositionally "mature" when it is well-sorted (has a small range of sizes) and well-shaped (is more rounded). 10. As sediment is transported what happens to size, sorting, shape, angularity, and compositional maturity? a. As sediment is transported, its size decreases, its sorting increases, its shape becomes more spherical, its angularity decreases/it becomes more rounded, and compositionally it is made up of more quartz.

1. Where is the thickest sediment in the ocean basins, Why

a. Sediment is thickest in the ocean basins in the areas around the edges of continents. This is because continents provide lots of sediment in the form of runoff of small pieces of rock and other debris from land. b. Sediments are also thickest in the areas furthest away from spreading centers, because these areas are the oldest and therefore have had the time to accumulate the most sediment.

7. What is the CCD and how does it determine what sediment is deposited in the oceans

a. The CCD is the depth below which there are no carbonate sediments, because below that point, the sediments are dissolved. This means that carbonate sediments are mainly found in shallow water, where the sea floor is still warm enough to allow them to exist.

19. What is the PETM and how is it expressed in sediment cores

a. The PETM (Paleocene-Eocene thermal maximum) was a time period during which temperatures soared and polar ice melted, probbaly caused by a sudden and large release of carbon into the air. The carbon could have come from methane hydrates escaping the ocean and releasing their carbon. The PETM can be seen in sediment cores because its color changed from white to red, because the white shells of biogenous sediment were dissolved away by the acidified ocean.

17. Why are the Cliffs of Dover, white

a. The cliffs of Dover are white because of the "marine snow" on them. They are made of white calcareous chalk made mostly of sediment from foraminifera and coccolithophores.

22. How fast do tsunamis move

a. The tsunami moves as fast as a commercial jet - it's the fastest known phenomena. It moves a little less than a mile a second. It can move that fast because it moves energy, not water.

3. What are the two sources of terrigenous sediment

a. The two sources of terrigenous sediment are river delta deposits and shorline erosion.

23. How big are the waves in this part of the Southern Ocean

a. The waves are around 60 feet high, as tall as a 6 story building.

26. What really "fueled" Katrina

a. Warm ocean water was the "gasoline" to Katrina. The hurricane sucks in the heat from the surface Caribbean sea, which is often 80º or hotter, and the wind speed increases as cool air rushes in below the warm air. This begins a cycle that intensifies the storm.