Oceanography Test 1 - Questions
List the characteristics of Cosmogenous sediment.
Tektites and Space Dust
Describe the most common types of cosmogenous sediment and give a probable source of these particles.
Tektites-Meteor Impacts. Space dust-Space
What is the hypsographic curve?
Tells the structure of land vs. ocean.
Describe the process of how a drill ship like the JOIDES Resolution obtains core samples from the deep-ocean floor.
There is a funnel-like machine on the seafloor with a camera on the end. It can drill into 20 ft seas and retrieves the core sample.
How are sea water and pure water similar/different?
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Describe Ocean-Continent.
-Causes explosive volcanoes -Ocean plate is subducted -Continental arcs generate
Describe Ocean-Ocean.
-Denser plate is subducted -Deep trenches generate -Volcanic island arcs are created (how tsunamis are formed)
Why did scientists of the time doubt that continents had drifted?
-He could not present a mechanism for the movement. -Continents can't plow through ocean basins -Tidal gravitational attractions too small
Why does water have such unusual chemical properties?
-Hydrogen bonding: Polartiy means small negative charge at O end, small positive charge at H end. -Specific heat capacity: amount of heat required to raise the temperature of 1 gram of anything by 1*C. -Universal Solvent -Surface tension -Medium of life
List the characteristics of Hydrogenous sediment.
-Manganese nodules -Phosphates -Carbonates -Metal Sulfides
What evidence supports continental drift?
-Matching sequences of rocks and mountain chains -Similar rocks/fossils on different continents -Glacial ages and other climate evidence -Plant and animal fossils indicate different climate than today -Distribution of organisms -Modern organisms with similar ancestries
Explain the stages of progression that result in calcareous ooze existing below the CCD.
-Mid Ocean Ridge pokes above the CCD -Calcareous ooze is deposited on top and doesn't dissolve -Seafloor spreading happens - Spreads, and Calcareous sediment eventually falls below the CCD
Why does a map of worldwide earthquakes closely match the locations of worldwide plate boundaries?
-Most large Earthquakes occur at subduction zones. -Earthquake activity mirrors tectonic plate boundaries.
What features occur at plate boundaries?
-Mountains -Oceans -Valleys -Volcanoes -Earthquakes
Describe Continent-Continent.
-No subduction -Tall mountains uplifted Basaltic material is recycled
How does seawater salinity vary at the surface and with depth?
-Places of low latitude there is high salinity -Places of high latitude there is low. This is all affected by runoff, melting icebergs, sea ice forming and evaporation.
What types of past environmental conditions can be inferred by studying cores of sediment?
-Sea surface temperature -Ocean current -Changes in climate -C02 levels
What factors affect sea water density?
-Temperature -Salinity -Pressure -Cold/salty is the most dense -warm/fresh is not so dense
Describe seafloor spreading and why it was an important piece of evidence in support to plate tectonics.
-The formation of new ocean crust, plates move apart and magma rises. Mid-ocean ridge is the spreading center. -Subduction zones=edges of the ocean/near land. -It's important because it helps explain continental drift theory.
List the 4 basic types of marine sediment.
1. Lithogenous 2. Biogenous 3. Hydrogenous 4. Cosmogenous
How salty is seawater?
35 parts per thousand
Describe how excess heat energy gets absorbed by Earth's low latitude regions is transferred to heat deficient higher latitudes.
As water gets denser, it sinks, and moves from lower latitude(equator) to higher latitude(poles). As water moves closer to poles it comes in contact with denser water, which makes it rise and spread the heated water.
Oceanic Crust
Basalt, volcanic Density: 3 gm/cm^3 200 million years old
Why are biogenous oozes the most common pelagic deposits?
Biogenous ooze comes from the ocean, pelagic is deep water.
List the two major chemical compounds of which most biogoenous sediment is composed and examples of the organisms that produce them.
Calcium Carbonate- Cocolithothores & Foraminifera Silica- Radiolarians & Diatoms
List the characteristics of Biogeonus sediment.
Calcium Carbonate: Cocolithothores and Foraminifera Silica: Diatoms and Radiolarians
Describe the difference in earthquake magnitudes that occur between 3 types of plate boundaries, and include why these differences occur.
Divergent - Shallow earthquakes Convergent - Deep earthquakes Transform - Shallow but strong earthquakes
What evidence supports plate tectonics?
Earth's magnetic field and paleomagnetism Earth has magnetic polarity North and South polarities Magnetic polarity in igneous rocks Magnetic dip data (poles reverse)
How does seawater salinity vary?
Evaporation increases salinity like freezing water but fresh water decreases salinity. -Open ocean salinity= 33-38% -Costal areas it varies more widely -Ocean surface water= 1.022 to 1.030 g/cm^3
Describe manganese nodules, including what is currently known about them and how they form.
Fist size lumps of manganese iron and other metals. Accumulation rate is slow.
Name and describe the 3 stages of coral development. How does this sequence tie into the plate tectonic model?
Fringing- develop along landmass(attached to land). Barrier- separated from landmass by a lagoon. Atolls- reefs continue to grow over volcanoes are submerged (no island left)
Continental Crust
Granite Density: 2.7 gm/cm^3 4 billion years old *never gets subducted*
Why is lithogenous sediment the most common neritic deposit?
Lithogenous comes from land, neritic is near land. It's difficult for lithogenous sediment to be moved to the deep ocean (unless glaciers)
How are marine sediments collected and what historical events do they reveal?
Ocean Drilling Program- Texas A&M They drill down and bring up the cores of sediments to study.
Describe the ways in which dissolved components are added and removed from seawater.
One way to remove a solute is to evaporate the water so the solute will be left behind. To add a solute, just stir until dissovled.
Describe the origin, composition, and distribution of biogenous sediment.
Origin- Calcium carbonate, from dead animals. Composition- Animal remains. Distribution- Productivity, Destruction, Dilution
Describe the origin, composition, and distribution of hydrogenous sediment.
Origin- Chemical reactions in the water. Composition- Manganese Nodules Distribution- Diverse Environments
Describe the origin, composition, and distribution of lithogenous sediment.
Origin- Derived from land. Composition- Small particles of rock. Texture- Fine-grained or coarse-grained.
Describe the origin, composition, and distribution of cosmogenous sediment.
Origin- Space Composititon- Meteor debris, tektites Not a lot
List the characteristics of Lithogenous sediment.
Produced by weathering & greatest quantity by continental margin. -Neritic: Near land and shallow water. -Pelagic: Middle of the ocean and deep water.
Cite the lines of evidence Alfred Wegener used to support his idea of continental drift.
Proposed pangea- one big continent and panthalassa- one large ocean, noted a puzzle like fit.
If silicious ooze is slowly but constantly dissolving in seawater, how can deposits of silicious ooze accumulate on the ocean floor?
Silica tests accumulate faster than seawater can dissolve them.
What evidence is used to support the hypothesis that ocean salinity has remained constant through time?
The ocean layers
How is the age distribution pattern of the Hawaiian islands-Emperor Seamount Chain explains by the position of the Hawaiian hotspot? What could have caused curious bend in the chain?
The older hotspots are more north(far away). There could have been a change in plate motion.
Why is it so rare to find pure marine sediment type? Give examples of mixtures of sediments.
Typically one sediment type dominates in different areas of the sea floor. EX) calcareous ooze containing silicious ooze
Most lithospheric plates contain both oceanic and continental type crust. Use plate boundaries to explain why that is true.
Very few plate boundaries follow the edge of the continents.
How does the specific heat capacity of water compare with that of other substances?
Water has an abnormally high heat capacity. It effects climate because it is able to store a large amount of heat, meaning there is less heat in the atmosphere. Hence, the weather is cooler.
Width and depth of an ocean basin?
Width: 5,000-10,000 KM Depth: 4,000 M
