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Earth Science Semester 2 Study Guide
Terms in this set (48)
How much of Earth is covered by oceans. How is the ocean water distributed over Earth's surface?
71% of Earth's surface is covered by oceans. Oceans cover 81% of the southern hemisphere, and 61% of the northern hemisphere.
Two types of technology used by scientists to collect data about oceans are:
• Sonar: used to learn more about the topography of the ocean floor. Ocean depth is determined by a sound signal sent by scientists to the ocean floor. Scientists time the amount of time it takes for the reach the bottom of the ocean floor and return to the surface as an echo. (Sound Navigation and Ranging.)
• Submersibles: Under water vessels which can be remotely operated or carry people to the deepest areas of the ocean, have allowed scientist to explore new frontiers. Can be used to discover geologic features, similarly to how Alvin found hydrothermal vents and previously unknown sea creatures.
There are a few clues that indicate that oceans formed early in Earth's geologic history, some are:
• Rocks that age back about 4.56 billion years that were formed from sediments deposited in water
• Ancient lava flows, some of which have glassy crusts that form only when molten lava is chilled rapidly underwater.
The water in Earth's early oceans originated from either two sources, or both:
• Remote sources: Comets and meteorites that travel throughout the solar system and occasionally collide with earth, releasing water, which over time could have accumulated to form the oceans on earth.
• Local sources: When volcanism occurs, gases, which consist mostly of water vapor and carbon dioxide, are emitted. It is documented that shortly after the formation of earth, when the plant was much warmer than it is now, an episode of massive, violent volcanism took place over the course of several hundred years. When this happed the water vapor and carbon dioxide contained inside the volcano are released, and as earth's crust cools, the water vapor condenses, and become water.
Predict some possible consequence of rising sea level.
Sea level rising is caused by increase in temperature. Normally, the sea level rises and falls back and forth, so a balance is maintained, but if the temperature just continually rose, then the sea level would continue to rise without ever falling, and this could be catastrophic. Think about hurricanes, many homes would become below sea level, and those homes that are already below sea level, would become even lower beneath sea level. Many more homes would be destroyed, and lives taken away. A category three hurricane could become a category five hurricane, and so on and so forth. For the sake of everyone, scientists should try to keep the sea level down as much as possible. Also, flooding could occur at pretty much any coastal city could be submerged under water. We would have significantly less land to inhabit.
level of the oceans surfaces; which have risen at a rate of about 3mm per year
Technique that directs sound waves at an angle to the seafloor or deep-lake floor, allowing underwater topographic features to be mapped
Compare and contrast North Atlantic Deep Water and Antarctic Bottom water.
Both are formed by sinking water. North Atlantic deep water is typically warmer than Antarctic Bottom water.
The factors that affect the chemical properties of seawater are:
• Wave action
• Vertical movements of water
• Biological activity
Which is more dense, cold freshwater or warm seawater?
I believe that warm seawater is more dense than cold freshwater because the density of water increases with salinity, and seawater contains significantly more amounts of salt than freshwater. Also because the density of water increases with the decrease of the temperature of the water. So if temperature were the only factor, I would say the colder water is more dense than the warm water, but considering salinity, I have to say that I believe that warm salt water is more dense that cold freshwater.
Measure of the amount of salts dissolved in seawater, which is 35 ppt, or 3.5% on average.
Coastal area of lowest salinity often occurs where the lower end of a fresh water river or stream enters the ocean.
Plots, changing ocean water temperatures against depth, which varies, depending on locations and season.
Transitional ocean layer that lies between the relatively warm, sunlit surface layer and the colder, dark, dense bottom layer and is characterized by temperatures that decrease rapidly with depth.
Describe how surface currents in gyres redistribute heat between the equator and the poles.
Surface currents in gyres redistribute heat between the equator and the poles by first deflecting the parts of all gyres closest to the equator move towards the west as equatorial currents, and when the currents from landmasses they are deflected towards the poles where the waters there carry warm, tropical water into higher, colder latitudes.
Note: Gyres are closed circular current systems.
Explain how tides form.
Tides are the periodical rise and fall of sea level and they form because of the gravitational attraction among Earth, the Moon, and the Sun, as well as the effect of Earth's rotation. When the Sun, the Earth, and the Moon are aligned, a spring tide occurs, which is the period of time in which the tidal range is the highest. When the Moon, the Sun, and the Earth form a 90 degree angle, a Neap tide occurs, which is the period of time in which the tidal range is lowest.
Compare and contrast surface currents and density currents.
*Generated by wind; Tropical ocean surface currents, as a result of tropical trade winds blowing from east west, also flow from east to west.
*Mainly the top 100 to 200 meters of the ocean experience these currents
*Move rather quickly, about 100 km a day
*Follow predictable patterns and are driven by Earth's global wind systems
*The direction of the surface currents can also be affected by landforms, such as continents, as well as the Coriolis effect.
*Are caused by the differences in the temperature and salinity of ocean water, which in turn affects density
*Occurs in the deep ocean
*Move slowly in deep ocean waters
*Follow a general path that is sometimes called the global conveyor belt
*The global conveyor belt begins when cold, dense water sinks at the poles, and after sinking the water masses slowly move away from the poles and circulate through the major ocean basins. After hundreds of years, the deep water eventually returns to the surface through upwelling, and once at the surface the deep water is warmed by solar radiation.
They are both currents.
Predict the effects of marine ecosystems if upwelling stopped.
If upwelling were to stop, I believe that many species of fish would become endangered, and eventually extinct. Some of the world's most productive ecosystems in the world, and they support fisheries. The deep-ocean waters are very nutrient-rich, and when upwelling occurs, these nutrient-rich waters are pushed up to the surface where they are utilized.
Asses the difference between spring tides and neap tides
*Spring tides form when the Sun, the Moon, and the Earth align, and the solar ties enhance the lunar tides, causing the high tides to become higher than usual, and the low tides to be lower than usual. The tidal ranges are the highest during this time. This only occurs during full and half-moon phases.
*Neap tides form when the Sun, the Moon, and the Earth form a 90 degree angle, and the solar tides diminish lunar tides, causing the higher tides to be lower than usual, and the lower tides to be higher than usual. This only occurs during a first-quarter moon, and a third-quarter moon.
The amount of dissolved salts in a fixed volume of seawater.
A transitional layer in which temperature rapidly decreases with depth.
The lowest point of a wave is the________?
The level of Earth's ocean is the ________?
______________ sends waves to the seafloor at angle.
__________ are the periodic rise and fall of sea level.
A _________ is caused by differences in the temperatures and salinity of ocean water.
The upward motion of water is called ___________?
The highest point of a wave is the __________?
Waves that collapse near shores are called ________?
What is used to measure ocean depth
What is the average depth of oceans:
What are the most common gases emitted by volcanoes:
a) Hydrogen and helium
b) Oxygen and nitrogen
c) Water vapor and carbon dioxide
d) Chlorine and hydrogen
What basic motion does water follow during the passage:
Which would have the largest impact on global ocean water density?
a) Strong winds
b) Increase in daylight hours
c) Long-term increase in air temperature
d) THUNDERSTORM WITH HEAVY PRECIPITATION
Which process does not remove salt from ocean water?
EVAPORATION OF WATER IN SUBTROPICAL REGIONS
Which types of tides occur when the Sun, the Moon, and Earth are aligned?
Which types of tides occur when the Sun, the Moon, and Earth form a right angle?
Explain how the moon influences tides.
The gravitational effect of the moon, which is closer than the sun, causes Earth's ocean to slosh towards the opposite sides of the Earth, creating tidal bulges.
Describe the features of deep-ocean basins.
• Abyssal plains: The flattest parts of the ocean floor 5 or km below sea level.
• Deep-sea trenches: The deepest parts of the ocean basins, which are elongated, sometimes arc-shaped depressions in the seafloor several kilometers deeper than the adjacent abyssal plans.
• Mid-ocean ridges: The most prominent features of the ocean basins, which run through all the ocean basins and have a total length of more than 65,000 km- a distance greater than earth's circumference; hydrothermal vents: A hole in the seafloor through which fluid heated by magma erupts.
• Seamounts and guyots: Submerged basaltic volcanoes more than 1 km high. Guyots are large, extinct, basaltic volcanoes with flat, submerged tops.
Identify which sediment sinks faster- pebbles or sand grains.
Pebbles sink faster because they are more dense than oozes.
Compare and Contrast Deep-sea mud and
*Consists of iron
*Dominant type of sediment on the deep ocean floor
*Sediments that contain a large percentage of particles derived from once living organisms.
*Consist of calcium carbonate or silica
Both the oozes and deep-sea mud of the deep ocean typically accumulate at a rate of only a few millimeters per thousand years.
Compare and contrast the characteristics of the three major areas of the continental margin.
*The shallowest part of a continental margin extending seaward from the shore
*Vary greatly in width, averaging 60 km wide
*The sloping regions beyond the continental shelves where the sea drops away quickly to depths of several kilometers.
*Slopes averaging nearly 100m per km
*The gently sloping accumulation of deposits from turbidity currents that forms at the base of the continental slope
*Can be kilometers thick
All are areas of the continental margin.
If there is little volcanic activity on abyssal plains, yet they are dotted with thousands of seamounts, from where did these extinct volcanoes come?
If there is little volcanic activity on abyssal plains, yet there are dotted with thousands of seamounts, it stands to reason that they must have started out at the mid-ocean ridge and pushed out by plate tectonics.
Continental margin: Abyssal plain: Smooth, flat part of the seafloor covered with muddy sediments and sedimentary rocks that extends seaward from the continental margin.
Deep-sea trench: Elongated, sometimes arc-shaped depression in the seafloor that can extend for thousands of kilometers, is the deepest part of the ocean basin, and is found primarily in the Pacific Ocean.
Mid-ocean ridge: Chain of underwater mountains that run throughout the ocean basins, have a total length of over 65,000 km, and contain active and extinct volcanoes.
Seamount: Basaltic, submerged volcano on the seafloor that is more than 1 km high.
Guyot: Large, extinct, basaltic volcanoes with flat, submerged tops.
Area where edges of continents meet the ocean; represents the shallowest part of the ocean that consists of the continental shelf, the continental slope, and the continental rise.
Shallowest part of a continental margin, with an average depth of 130 m and an average width of 60 km, that extends into the ocean from the shore and provides a nutrient-rich home to large numbers of fish.
Sloping oceanic region found beyond the continental shelf that generally marks the edge of the continental shelf that generally marks the edge of the continental crust and may be cut by sub-marine canyons.
Rapidly flowing ocean currents that can cut deep-sea canyons into continental slopes ad deposit the sediments in the form of a continental rise.
Gently sloping accumulation of sediments deposited by a turbidity current at the foot of a continental region.
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