Transcript mid-ocean ridge

Topography of the Ocean Floor
Parts of an ocean wave
•
The winds cause waves
on the surface of the
ocean (and on lakes).
The wind transfers some
of its energy to the water,
through friction between
the air molecules and the
water molecules.
Stronger winds (like
storm surges) cause
larger waves.
Guyots and Sea Mounts
• A guyot /giɘʊ/, also known as a
tablemount, is a flat-topped seamount.
• Guyots are most commonly found in the
Pacific Ocean
•
Location and formation
• There are thought to be an estimated 50,000
seamounts in the Pacific basin. The Emperor
Seamounts are an excellent example of an
entire volcanic chain undergoing this process.
• Guyots show evidence of having been above
the surface with gradual subsidence, the sinking
down of land resulting from natural shifts,
through stages from fringed reefed mountain,
coral atoll, and finally a flat topped submerged
mountain. Their flatness is due to erosion by
waves, winds, and atmospheric processes.
Mid Ocean Ridge
• A mid-ocean ridge or
mid-oceanic ridge is
an underwater
mountain range,
typically having a
valley known as a rift
running along its
spine, formed by plate
tectonics
• The mid-ocean ridges of the world are
connected and form a single global
mid-oceanic ridge system that is part
of every ocean, making the midoceanic ridge system the longest
mountain range in the world. The
continuous mountain range is
65,000 km (40,400 mi) long and the
total length of the system is
80,000 km (49,700 mi)[
Sea floor Spreading
• The uplifted sea floor
results from
convection currents
which rise in the
mantle as magma at
a linear weakness in
the oceanic crust, and
emerge as lava,
creating new crust
upon cooling.
divergent plate
boundary.
Continental Shelf
• Combined with the sunlight available in shallow
waters, the continental shelves teem with life
• Name a few
Continental Shelf Food Web
The global continental shelf,
highlighted in cyan
Continental Shelf
• The continental shelf is the extended perimeter
of each continent and associated coastal plain,
and was part of the continent during the glacial
periods, but is undersea during interglacial
periods s (times of freezing and melting) uch as
the current epoch by relatively shallow seas
(known as shelf seas) and gulfs.
• The largest shelf – the Siberian Shelf in the
Arctic Ocean – stretches to 1500 kilometers (930
miles) in width.
• Some continients do not have a continental
shelf, but rather directly to the slope.
• The continental slope connects the
continental shelf and the oceanic crust. It
begins at the continental shelf break, or
where the bottom sharply drops off into a
steep slope. It usually begins at 430 feet
(130 meters) depth and can be up to 20 km
wide. The continental slope, which is still
considered part of the continent, together
with the continental shelf is called the
continental margin.
Continental Slope
• The continental slope is a submarine geological feature which
connects the continental shelf to the abyssal plain, beginning at a
depth of around 460 feet (140 meters). Together, the continental
slope and the continental shelf are often referred to as the
“continental margin,” in a reference to the fact that the combined
features are found at the margins of the Earth's continent. The
continental slope also happens to mark the boundary between the
part of the world's ocean scientists are familiar with and the
mysteries of the deep sea.
Life in the Continental Slope
• As the continental slope plunges into the deeper parts of
the ocean, conditions quickly change. The water
becomes much colder and more sluggish. It is also
totally devoid of life, and oxygen levels decline as well.
As a result, the ocean life along the continental slope is
markedly different than that found along the continental
shelf, as it must be much more tolerant of extreme
conditions. The deeper these animals live, the more
intense the pressure gets; organisms from shallower
depths, including humans, would literally start to implode
from the pressure
Frilled Shark
• Fang tooth fish
•
FREAKY CRITTERS
from the deep
• Frilled Shark
• Fang tooth fish
Abyssal Plain
Abyssal Plain
• Abyssal plains are flat or very gently sloping areas of
the deep ocean basin floor. They are among the Earth's
flattest and smoothest regions and the least explored.
• Abyssal plains result from the blanketing of an originally
uneven surface of oceanic crust by fine-grained
sediments, mainly clay and silt.
• The remainder of the sediment comprises chiefly dust
(clay particles) blown out to sea from land, and the
remains of small marine plants and animals (the
plankton), which sink from the upper layer of the ocean,
known as Pelagic sediments.
Deep Sea Trench
• Trenches define one of the most important
natural boundaries on the Earth’s solid surface,
that between two lithospheric plates. There are
three types of lithospheric plate boundaries:
divergent (where lithosphere and oceanic crust
is created at mid-ocean ridges), convergent
(where one lithospheric plate sinks beneath
another and returns to the mantle), and
transform (where two lithospheric plates slide
past each other).
Length North to South: 11,000 miles
Deepest point: Mariana Trench at 35,797 feet
Meaning of 'Pacific': 'Peaceful'
Average Depth: 14,000 feet
Islands in the Pacific: About 25,000
Temperature: 32 °F to 84 °F