| As many
interesting geological features as there are on land, nearly as many exist within, under,
and at the boundaries of the
oceans. Mountains, valleys, volcanoes, islands, plains, canyons -- all
exist in similar form in the marine realm. They also use
remote sensing technology to map the ridges and valleys. It has been
written that the ocean bottoms are the most active
places on Earth, from a geological perspective.
Conditions at many of these sites make it
difficult for marine geologists to visit and study. Before the technological advances
of only a few decades ago -- piloted submersibles, remotely operated
vehicles (ROVs), and programmable acoustic
instruments attached to ships -- oceanographers could only speculate
about the very existence of underwater geological
features. Such advances have not only proven the existence of
underwater features, they have made it possible to develop
accurate maps and detailed, 3-D computer models of the seafloor.
Geological oceanographers study the
formations, composition, and history of the seafloor. They examine sediments,
including physical characteristics such as size, shape, color, and
weight; chemical characteristics, such as composition and
how sediments interact with the environment; and other factors,
including sediment age, origin, distribution, and transport. By
combining their knowledge of marine chemistry and physical
oceanography, marine geologists help piece together
information about how the Earth formed and how the movement of plates
and continents results in events such as volcanoes
and earthquakes. Also, marine geologists work with biologists and
chemical oceanographers to learn more about historical
climate records and animal and plant life by examining sediment and
rock cores for fossils and analyzing sediment
composition using radiocarbon dating and other methods.
Related
Occupations
* Seismology
* Ocean Drilling
* Ocean Mining, Oil and Gas Exploration
* Coastal
Geology
Some of the major areas of specialization within
the field of geological oceanography are described below:
Seismology
Marine seismologists map the Earth's interior
structure by looking at changes in the way sound travels through the planet's
various layers. These sound patterns appear as "waves."
Seismic energy travels as an elastic wave, meaning that it can be
reflected from the seafloor ("reflection") or it can
penetrate through the seafloor and the layers within the Earth's interior and
be bent as it travels ("refraction"). An important tool used
by marine seismologists to "read" patterns of sound waves is the
seismogram. You have probably seen examples of seismograms, which
depict measurements of earthquake patterns. The
instrument that records these measurements is called a seismometer.
Though it's hard to imagine, there are thousands of
microearthquakes beneath the ocean floor each day!
Ocean Drilling
The international Ocean Drilling Program (ODP),
successor to the Deep Sea Drilling Project (DSDP) begun in 1968, is a
partnership of scientists and governments created to explore the
Earth's origin and evolution beneath the seafloor. Aboard the
drill ship JOIDES Resolution, researchers from around the world gather
samples of sediment and rock from below the ocean
floor. (The "JOIDES" part of the ship's name stands for
Joint Oceanographic Institutions for Deep Earth Sampling.)
Important discoveries made by the ODP include a
new understanding of the causes and history of ice ages, the evolution of
the continental margins, Earth's tectonic processes, marine
sedimentation, and the origin and evolution of oceanic crust.
Investigators involved in the ODP may specialize in sedimentology (the
study of matter that settles to the bottom of the sea),
paleontology (the study of fossil plants and animals and of the rock
formations in which these fossils are found), petrology
(the study of the origin, occurrence, structure, and composition of
rocks), geochemistry, geophysics, and paleomagnetics.
Ocean
Mining, Oil and Gas Exploration
Ocean manganese nodules -- small, dark, and
round-shaped nodules that contain manganese, nickel, copper, cobalt, and
other minerals -- are found along the floor of the Atlantic and
Pacific oceans. The nodules were first discovered on the famous
oceanographic Challenger expedition of the 1870s. Steel production
requires millions of tons of manganese annually. Though
ocean mining for manganese nodules has generated a great deal of
interest, several factors have served as obstacles,
including the difficult ocean terrain, the high cost, and political
and international difficulties relating to its legality.
Similar problems associated with oil and gas
exploration have caused international and national debate. While no one knows
the exact extent of the oil and gas deposits in the ocean,
oceanographers have made important discoveries about these
potential reserves. The cost of exploring these sites is high. And,
even if oil or gas reserves are found, recovering the
resources is not always pursued due to the high cost of developing the
site or other reasons.
Partnerships between scientists and industry are
important in the area of oil and gas exploration; oil companies constantly
seek new reserves, while science makes it possible for companies to
locate, analyze, and reach the resource. Current
production takes place in the oceanic areas of continental margins,
such as the Gulf of Mexico and the North Sea.
Coastal Geology
An increasingly important area of marine geology
is coastal geology. Throughout history, the human population has shown a
tendency to settle along the world's 273,000 miles of coastline. The
effects of humans inhabiting our shores and coastlines
have become increasingly apparent. Coastal pollution and waste
disposal are creating problems and costing government and
industry billions of dollars in research and remediation efforts.
Although the percentage of people living on the coast is
expected to remain fairly constant over the next few decades, total
numbers are expected to increase as population continues
to increase.
In addition to human effects on our shores,
natural coastal processes such as rising sea level, erosion, and sediment
transport, and storm-related events such as flooding, severe erosion,
and storm overwash make our coastal areas dynamic
environments. Often, humans react by attempting to protect structures
situated along the coast, including homes,
businesses, and roads, even when these structures are located on land
forms, such as barrier beaches, that are "temporary"
in a geologic sense of time. To protect these structures, coastal
engineers have developed and constructed seawalls, jetties,
groins, and bridges. More recently, natural or "soft
solutions" such as constructed wetlands and salt marshes have been
developed to slow the effects of coastal processes. Coastal geologists
and coastal engineers, working with oceanographers
from each of the disciplines, will be instrumental in forming policy
and management options to minimize the conflicts between
coastal development and natural processes.
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