oceanography: seafloor topography
TRANSCRIPT
-The arrangement of the natural and artificial features of an area
-A detailed description or representation on a map of the natural and artificial features of an area
The study of the ocean floor topography is interesting since it
offers details of a vast area comprised of hills, mountains, and valleys, all covered with water. The ocean floor topography starts with
the Outer Continental Shelf followed by the Continental Slopes, and subsequently the Ocean Floor.
refers to the different forms in which the ocean floor bottom can exist
-boundary between the earth and the ocean in which radical geological changes are observed
- This zone consists of the Outer Continental Shelf followed by the Continental Slopes
- shallow, slopes progressively, and normally holds water that is not very deep
-As the Continental Shelf is crossed, the ocean floor descends steeply. These sharply sloping sections are known as the Continental Slopes. They identify the border between the granite of the continent, and the basaltic crust of the ocean.
- Deep valleys have been observed in the Continental Slopes. It is believed that these valleys have been created due to the earthquakes, or have been eroded by violent ocean currents.
-a layer of the pelagic zone of the ocean. "Abyss" is derived from a Greek word
which means ’bottomless’.
Ocean waters trapped in the pore spaces of sediments make up most of the present-day hydrosphere.
The total mass of water in the oceans equals about 50% of the mass of sedimentary rocks now in existence (5% of the mass of the whole Earth’s crust).
Deep and shallow ground waters constitute a small percentage of the total water locked in the pores of sedimentary rocks—on the order of 3 to 15%.
The amount of water in the atmosphere at any one time is trivial,
equivalent to 0.013 x 106 cubic kilometers of liquid water (0.001% of
the total water at Earth’s surface).
- more than 1% of Earth’s water-3% or more during the height of glaciations of the Pleistocene Epoch (2.6 M to 11, 700 yrs. ago)
The Pleistocene Epoch under Cenozoic Era
The amount of water discharged each year into the oceans from the land is approximately equal to the total mass of water stored at any
instant in rivers and lakes.
-accounts for only 0.005% of the water at Earth’s surface
-exerts the most direct influence on evaporation from soils
-H2o composition (2 Hydrogen atoms and 1 Oxygen atom)-0.00004% of the total water at terrestrial surface-plays a major role in transpiration (transport of water vapor back to the atmosphere)
-describes the boundary between water-saturated ground and unsaturated ground
- Below the water table, rocks and soil are full of water.
- generally 15 to 90 meters below the land surface
In Manila, Philippines, an old well provides water for the locals. This well punches through the area's water table, allowing water
from the aquifer to be easily accessed.
- a body of permeable rock that can contain or transmit groundwater
-pockets of water existing below the water table
AQUIFER
An area’s water table can fluctuate as water seeps downward from the
surface. It filters through soil, sediment, and rocks. This water includes
precipitation, such as rain and snow. Irrigation from crops may also
contribute to a rising water table.
Water Tables are influenced by:
-an excavation or structure created in a ground by digging, driving, boring, or
drilling to access ground water in underground aquifers
Wells were first constructed at least 8, 000 years ago.
-drawn by a pump or containers that are raised mechanically or by hands
- a shallow hole dug down into the water table
– a traditional method of obtaining water, which has been used for thousands of years
- is a well dug vertically by driving in piping directly.
- It is a capture engineered structure that consists of a perforated pipe with a pointed end, which is driven by a variety of techniques as far as the water table, in soft of medium-hard ground. Other names are instantaneous well or sand-point well.
-consists of a hole bored into the ground, with the upper part being lined with casing
- Can get water from a much deeper level than dug wells can—often up to several hundred meters
- any natural situation where water flows from an aquifer to the Earth’s
surface - used for variety of human needs including drinking water, domestic
water supply, irrigation, mills, navigation, and electricity
generation
—the term ‘seep’ refers to springs with small flow rates in which the source water has filtered through permeable earth
- discharge from faults, joints, or fissures in the earth in which springs have followed a natural course of voids or weaknesses in the bedrock
- water flows from underground caverns
- both arise as a result of volcanic activity
a pool of hot water that has seeped through an opening in Earth’s
surface
- a type of hot spring, which is a pool of hot water that has seeped
through a vent or opening in Earth’s surface
-came from the word Geysir (Icelandic for “gusher”)—a name of an erupting flow of heated water from the ground in Iceland
-at least 15o F (8.3o C) temperature of water, and can reach as high as 200o F (93 o C)
- Geysers are rare; there are only approximately 700 geysers known to exist on Earth.
1. FOUNTAIN GEYSERerupts like a fountain in various directions
through a pool that fills an open crater before or during the eruption.
Ex. Great Fountain Geyser (in Firehole Lake Area, Lower Geyser Basin, Yellowstone National Park, Wyoming)Only predictable geyser basin in the Lower Geyser Basin
Erupts every after 9 to 15 hours
2. CONE GEYSER- erupt in a fairly narrow jet from a vent in a cone-like mound formed of geyserites
Ex. Castle Geyser (in Upper Geyser Basin, Yellowstone National Park, Wyoming)World’s oldest active geyserErupts every 9 to 11 hours
Shoots out a jet of water between 60-90 feet (18 to 27 meters)