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The Submarine Canyons
Presentation · March 2011
DOI: 10.13140/RG.2.2.19047.65446
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2. 1
SUBMARINE CANYONS
By Prof. A. Balasubramanian, University of Mysore
INTRODUCTION
Continents and oceans are the two first order relief features of the world. Continents are bordered by seas
and oceans. Beaches form the interface between land and the water along seas and oceans. The coastline
is the boundary between continental and oceanic masses. The ocean floor is uneven. The surface beneath
the oceanic waters is characterized by a lot of relief features. The structure, configuration and relief
features of the oceans also vary from each other. On the basis of Bathymetry and other studies, the
morphology of Ocean basins include:
* Continental margins encompassing Continental shelf & Continental slope,
* Deep ocean basins encompassing Abyssal plains , hills, trenches & Mid-oceanic ridges.
Continental shelf is the first morphologic unit of the oceans located adjacent to the coastline.
It is an extension of the land beneath the ocean surface. The width of the shelf zone ranges from 60 to
more than 1500 km. The water depth of this region may go upto 150 m. At present, continental shelf
comprises 6% of Earth’s total area. 70% of the continental shelves are covered with thick deposits of silt,
sand, mud and sediments derived from the land.
The continental Slope begins at the outer edge of the continental shelf. The slope is much steeper than the
shelf. It plunges down to a depth of 4 km. The width may range from 20 to 100km. The slope may range
from 5°to more than 60°.
The boundary of the continental shelf on the ocean side is determined by an abrupt change in the slope
and a rapid increase in depth. This particular portion is called as the continental shelf break.
Continental slopes are the longest and highest slopes on the earth. The slope may be straight or curved.
The most outstanding features of the continental slopes are the presence of features like submarine
canyons.
These are geologically significant, oceanographically important underwater features.
In this episode, the following aspects are explained:
1. The land beneath oceans
2. Submarine Canyons
3. Characteristics of submarine canyons
4. Origin and types
5. Distribution of submarine canyons

3. 2
1. THE LAND BENEATH OCEANS
New technologies and the development of highly maneuverable submersible crafts have allowed scientists
to go down to explore the deep oceans of the world.
Based on these studies, the world’s marine provinces can be divided into two major parts as
1) the continental margin and
2) the deep-sea basins.
The Continental margin represents the edge of continents under the sea or ocean.
A schematic profile of the continental margin to the deep-sea shows the following zones:
1. The coastal plain is the first part of the waters edge. It includes the beaches, mainly covered by
unconsolidated sediments. These are subjected to wave energy that moves these sediments by converging
on headlands.
2. The inner and outer continental shelf. It is about 70 km wide, bordering the continent –topography. It
generally resembles that of the coastal plain. It has a gentle slope of about 0.1 degree (1.9m/km).
Sediments are transported across this shelf by the oceanic currents.
3. The continental slope is rather steep slope with 4 degrees (76m/km), following the continental shelf
break. Some slopes are cut by the submarine canyons. These canyons are spaced closer together as the
slope increases. Deep-sea fans are also formed where these canyons empty out their sediments onto the
deep-sea floor.
4. The upper and lower continental rise comes next. These are usually smooth due to sediment cover. The
slope may be of 0.5 degrees (9.5m/km).
The final part is the Deep-ocean Basin.
The schematic profile of an ocean basin shows the following ten features:
1. Submarine volcanoes.
2. Seamounts are isolated submarine hills, steep sides, volcano-shaped - more than 1 km in relief.
3. Mid-ocean rises and ridges.
4. Abyssal plains.
5. Knolls - or abyssal hills (mostly in Pacific) 30-1,000m in relief, several nm wide, origin unknown, very
common less than 1000m elevation, not completely smooth.
6. Trenches - mostly in the Pacific - mark the transition between the continents and the ocean basins.
These are steep sided - as deep as 11000m. Some are "higher" than the Mt. Everest from the base.
7. Island arcs - on landward side of trenches - areas of active mountain building - often with high
mountains on the adjacent continent.
8. Fracture zones in the oceans are generally east-west oriented. They extend several 1000km across the
major Oceans.
9. Guyots or flat topped seamounts. These gets eroded seamounts during exposure at the surface. They are
more than 1 km in relief.
10. Atolls
The continental shelves are very significant zones for human and marine life. These zones are known for
their mineral deposits and for the occurrence of oil and natural gas. The continental shelf and slope
constitute the Continental margins. Submarine canyons are cutting across the continental margins and act
as feeders to the deep oceans.
2. SUBMARINE CANYONS

4. 3
Canyons are long, narrow and deep valleys of major and very old rivers. As the name implies Submarine
Canyons are deep narrow valleys of the continents extending inside the oceans.
A submarine canyon is a steep-sided valley on the sea floor of the continental slope.
Many submarine canyons are found as extensions to large rivers; however there are some that have no
such association.
Canyons cutting the continental slopes have been found at depths greater than 2 km below sea level.
They are formed by powerful turbidity currents, volcanic and earthquake activity.
Many submarine canyons continue as submarine channels across continental rise areas and may extend
for hundreds of kilometers.
Submarine canyons serve as major conduits for transporting sediment from land and the shelf to the deep-
sea floor. Undersea canyons are prominent erosional features along both the U.S. Pacific and Atlantic
continental margins.
Similarly, the distinction between submarine canyons and submarine erosional channels is not
straightforward. Thus, alternative terms, such as gullies, channels, troughs, trenches, fault valleys, and sea
valleys, have been used for submarine canyons.
A submarine canyon may begin as a river pours into the ocean, eroding a channel in the shallow
continental shelf. But much of the carving may be done by torrents of muddy water stirred up by storms,
earthquakes, or other big events.
Submarine canyons also develop along the slopes of many islands (for example, Hawaii).
They are associated with deep siliciclastic margins (Fig. 2) as well as shallow carbonate platforms.
Smaller erosional features on the continental slope are commonly called gullies (Fig. 2); however, there
are no standardized criteria to distinguish canyons from gullies.
.
Canyons are long, narrow and deep valleys of major and very old rivers. As the name implies submarine
canons are deep narrow valleys of the continents extending inside the oceans. Mostly they form the
extensions of continental river systems at their old stage. Submarine canyons are located on the
continental shelves and slopes. They are characterized by steep vertical walls resembling the continental
canyons with tributaries entering into it. Due to their existence under oceanic water, these are called as
submarine canyons. Some are associated with the mouth of large rivers and some are not connected with
any rivers. On the basis of morphogenetic processes, these are classified into
a) Glacially eroded canyons and
b) Non-glacial canyons.
The non-glacial submarine canyons are more in number than the glacial types in the oceans. These are
also widely spread over in all the oceans. Most of them are located in front of the mouths of the major
rivers. The longitudinal course of submarine canyons is usually sinuous. The gradient of submarine
canyons are steeper than the continental canyons. Most of them are several km wide at their heads and
their average length may be about 10 to 16 km.
These are hundreds of submarine canyons existing in the continental shelf and slope regions of many
oceans. The depth of these canyons vary from 600m to 3000m.
3. CHARACTERISTICS OF SUBMARINE CANYONS
Characteristics of submarine canyons:

5. 4
1. A typical canyon starts as a steep, narrow gorge cutting across the continental shelf and then
extends down the continental slope to greater depths of over 2000m.
2. The walls are generally steep and high in proportion to its width and ranging in age from
Mesozoic to Tertiary era.
3. The transverse section is v-shaped and the canyons have widening courses associated with
structural features like faults.
4. The longitudinal profiles show steeper gradient at the head, and gradually decreased to lower
regions without in any case form cliff-type features,
5. The submarine canyons have tributaries which usually begin at the continental slopes and leading
into the shelf forming dendrite pattern.
6. Canyons have rock falls of all degrees of harness including granitic and quartzite rocks, and
sedimentary rocks.
7. The canyons are distributed worldwide occurring near the coast and off the coast and also in
ocean basins.
Sediments of canyons:
The floors of these canyons show the presence of graded beds of
Coarse sand
Fine silt and
Fragments of plants and invertebrates transported from shallow water.
In some places, the graded sediments have also shown features like ripple marks which suggest the role of
relatively a strong current.
Deep sea fans:
Many of the Canyons deposit their sediments at the bottom of the continental slopes in the form of a fan
like conical structure. These are called as Deep sea fans. They are similar to alluvial fans seen along the
foot hills of mountains where the valley floors deposit the sediments. In many instances, it has been seen
that the volume of the fan is greater than the size of the canyon itself. Submarine canyons are found to be
the pathways for transport of huge volume of sediments due to their location.
The age of submarine canyons are yet another features to be understood. These are inferred by the age of
the rocks through which the canyons are cut. It has been observed that most of these submarine canyons
cut across the rocks of Cretaceous, Eocene, Miocene, Pliocene and Pleistocene sediments.
Submarine canyons are also major hotspots of biological production and fisheries catch
Scientists have found abundant life in many of these chasms, from their rims down to the bottoms of their
steep cliffs. This abundance may be due in part to nutrients from the rivers that feed the canyons.
In fact, submarine canyons are an important source of nutrients and sediments in the deep ocean.
They’re also a major source of pollution.
Until a few years ago, for example, New York and New Jersey dumped raw sewage into the Hudson
Canyon, which funneled it into the deeper Atlantic waters. Much of the sludge may still be inside the
canyon -- making the Hudson not only one of the world’s largest canyons, but one of its nastiest, too,
they say.
Submarine canyons resemble river canyons on land, usually having steep, rocky walls. They are found
along most continental slopes. Those of the Grand Bahama Canyon, which are thought to be the deepest,
cut nearly 3 mi (5 km) deep into the continental slope. Most submarine canyons extend only about 30 mi
(50 km) or less, but a few are more than 200 mi (300 km) long
Modern submarine canyons vary considerably in their dimensions. The average lengths of canyons has
been estimated to be about 34 mi (55 km); although the Bering Canyon is more than 680 mi (1100 km)

6. 5
long and is the world's longest submarine canyon. The shortest canyons are those off the Hawaiian
Islands, and average about 6 mi (10 km) in length. Submarine canyons are characterized by relatively
steep gradients. The average slope of canyon floors is 309 ft/mi (58 m/km). In general, shorter canyons
tend to have higher gradients. For example, shorter canyons of the Hawaiian group have an average
gradient of 766 ft/mi (144 m/km), whereas the Bering Canyon has a slope of only 42 ft/mi (7.9 m/km).
Submarine canyons are the most important conduits for funneling sediment from continents to oceans.
Submarine canyons, however, are zones of sediment bypassing, and little sediment accumulates in the
canyon until it ceases to be an active conduit.
To understand the potential importance in the rock record of any given submarine canyon, it is necessary
to understand sediment-transport processes in, as well as knowledge of, deep-sea turbidite and related
deposits that moved through the canyons.
There is no straightforward correlation between the final volume of the sedimentary deposits and size of
the associated submarine canyons.
Comparison of selected modern submarine canyons together with their deposits emphasizes the wide
range of scale differences between canyons and their impact on the rock record.
4. ORIGIN AND TYPES
Many mechanisms have been proposed for the formation of submarine canyons.
Most of them were debated during the 1940s and 1950s.
Origin of Submarine Canyons:
There are divergent opinions about the origins of submarine canyons. Majority of them consider that
these are of recent age of Cenozoic era and quaternary period. The major theories put forward are:
1. Diastrophic theory
2. Subaerial erosion theory
3. Submarine density current theory
4. Turbidity current theory
The Diastrophic theory explains the origins due to tectonic movements of the rocks like faulting warping
and sinking of the sea floor. Tensional forces lead to the formation of faults and graben on the continental
margins. The troughs of these zones later became submarine canyons.
The sub aerial erosion theory was put forward on the basis of the resemblance of these canyons to the
continental canyons in shape and depositional patterns. Deep cutting action of rivers forming such
features is a normal concept in geomorphology.
The submarine density current theory attributes the role of density currents originated in front of the river
months to form such canyons inside the seas and oceans.
The turbidity current theory attributes to the role of currents with fine sediments in creating these
erosional canyons. A turbidity current is a mass of water highly charges with materials in solution (or)
suspension. This flows with turbulent motion down the slope with normal marine waters. Agitation of
wave action on the shore is a serious mechanism of erosion.
Each submarine canyon has its own geology structure and morphological components of oceans and seas.
The submarine canyons are characterized by a lot of variations in their basement topography, bathymetry,
dimension and other ecological properties.

7. 6
Three types of submarine canyons have been identified:
1. Fairly small gorges which originate near the edge of continental shelf and run down into the
slope.
2. Canyons of river mouths extending from shelf to slopes.
3. Canyons having dendrite drainages which are deeply incised into the edges of shelf and slope.
The oceanographer canyon of New England shelf is an example for this. It goes upto 20 km inside edge
of the shelf and 150 km inside the sea. The floor has an average gradient of 1 in 23, with a v-shaped cross
section.
The Congo canyon is an example for this type. It extends about 30 km up the estuary of the river Congo.
The canyon is v-shaped and can be traced form 200 km and a depth of 2500m. The Canyon floors are
covered by silt and clay.
The Monterey canyon of southern California is a typical example of this type. It extends upto 75 km
offshore and the depth is about 3000m. The profile is similar to that of the Grand canyon of Colorado.
Subaerial erosion:
One basic theory was that the canyons of the present today were carved during glacial times, when sea
level was about 125 meters below the present sea level and the rivers flowed to the edge of the
continental shelf.
However, while many (but not all) canyons are found offshore from major rivers, subaerial river erosion
cannot have been active to the water depths as great as 3000 meters where canyons have been mapped, as
it is well established (by many lines of evidence) that sea levels did not fall to those depths.
Turbidity Currents:
The major mechanism of canyon erosion is now thought to be turbidity currents and
underwater landslides.
A turbidity current is a current of rapidly moving, sediment-laden water moving down a slope.A turbidity
current moves because it has a higher density and turbidity than the fluid through which it flows.The
sediments from the submarine canyon are then deposited on the deep-ocean floor.The erosional work
repeatedly carried out by these muddy torrents is thought to be a major force in the excavation of
submarine canyons
Turbidity currents are dense, sediment-laden currents which flow downslope when an unstable mass of
sediment that has been rapidly deposited on the upper slope fails, perhaps triggered by earthquakes. There
is a spectrum of turbidity- or density-current types ranging from "muddywater" to massive mudflow, and
evidence of both these end members can be observed in deposits associated with the deeper parts of
submarine canyons and channels, such as lobate deposits (mudflow) and levees along channels.
Mass Movements:
Mass wasting, slumping, and submarine landslides are forms of slope failures (the effect of gravity on a
hillslope) observed in submarine canyons. Mass wasting is the term used for the slower and smaller action
of material moving downhill; and would commonly include the effects of bioerosion:
the burrowing, ingestion and defecation of sediment performed by organisms. Slumping is generally used
for rotational movement of masses on a hillside. Landslides, or slides, generally comprise the detachment
and displacement of sediment masses. All are observed; all are contributory processes.
It is now understood that many mechanisms of submarine canyon creation have had effect to greater or
lesser degree in different places, even within the same canyon, or at different times during a canyon's
development. However, if a primary mechanism must be selected, the downslope lineal morphology of

8. 7
canyons and channels and the transportation of excavated or loose materials of the continental slope over
extensive distances require that various kinds of turbidity or density currents act as major participants.
In addition to the processes described above, submarine canyons that are especially deep may form by
another method. In certain cases, a sea with a bed significantly below sea level is cut off from the larger
ocean to which it is usually connected. The sea which is normally repleted by contact and inflow from the
ocean is now no longer replenished and hence dries up over a period of time, which can be very short if
the local climate is arid. In this scenario, rivers that previously flowed into the sea at a sea level elevation
now can cut far deeper into the bottom of the bed now exposed.
TheMessinian Salinity Crisis is an example of this phenomenon; between five and six million years ago,
the Mediterranean Sea became isolated from the Atlantic Ocean and evaporated away in roughly a
thousand years. During this time, the Nile River delta, among other rivers, extended far beyond its present
location, both in depth and length. In a cataclysmic event, the Mediterranean sea basin was flooded. One
relevant consequence is that the submarine canyons eroded are now far below the present sea level.
TYPES:
On the basis of morphogenetic processes, these are classified into
a) Glacially eroded Canyons and
b) Non-glacial Canyons
The non-glacial submarine canyons are more in number than the glacial types in the oceans. These are
also widely spread over in all the oceans. Most of them are located in front of the mouths of the major
rivers. The longitudinal course of Submarine Canyons is usually sinuous. The gradient of submarine
canyons are steeper than the Continental Canyons. Most of them are several Km wide at their heads and
their average length may be about 10 to 16 Km.
5. DISTRIBUTION OF SUBMARINE CANYONS
Submarine Canyons exist in almost all the three major oceans.
The following are the submarine canyons of the Pacific Ocean:
1) Bering Canyon
2) Monterey Canyon
3) Navarin Canyon
4) Pribilof Canyon
5) Scripps Canyon
6) Zhemchug Canyon
Three of the largest submarine canyons in the world are incised into the Beringian (North American)
margin of the Bering Sea.
Zhemchug Canyon has the largest cross-section at the shelf break and greatest volume of incision of slope
and
shelf.
1) The Bering Canyon, which is farther south in the Bering Sea, is first in length and total area.
In contrast, the largest submarine fans—e.g., Bengal, Indus, and Amazon—have substantially smaller,
delta-front submarine canyons that feed them.
The Bering Canyon is the longest of the Bering Sea canyons. It extends to about 400 km across the
Bering shelf and slope. It is confined at its eastern edge by the Aleutian Islands. The width of the canyon
at the shelf break is about 65 km. It is about two-third in dimension than that of the Zhemchug Canyon
and Navarin Canyons. Due to its great length, the Bering Canyon has the largest area. At a depth of 3200
m, the Bering Canyon reaches the Aleutian Basin.

9. 8
2) Monterey Canyon is the largest and deepest submarine canyon off the Pacific Coast of North
America. The canyon has three tributaries at its upper reaches in Monterey Bay, near California.
They are:
a) Minor Soquel canyon to the north
b) Main Monterey Canyon , with its head aligned east-west off Moss Landing
c) Carmel Canyon to the south.
Carmel canyon is the main tributary. It joins with the main canyon at an axial depth of 1800m. The
sinuous courses of Monterey canyon goes upto 2900m.
3) The Navarin Canyon is a submarine canyon in the Bering Sea. It is just as wide but less than half
as deep as the Zhemchug Canyon, which is the largest canyon in the world.
The Navarin Canyon is the third-largest to cut through the Beringian margin. It is the second-largest in
area. Though these canyons were not directly formed by rivers, it is postulated that when the sea level was
low during the Ice Ages, rivers such as the Yukon and the Kuskokwim may have shaped in part the heads
of these canyons. At the shelf break, it is approximately 100 kilometres (62 mi) wide.
4) Pribilof is a long submarine canyon rising from the Bering Abyssal plain on the floor of the
Bering Sea. It is located southeast of the Pribilof Islands, near Alaska. It runs across the edge of
continental slope and is 426 km long with walls 1800 m high. It is believed to have been formed
when large masses of sediments supplied by Alaskan and Siberian rivers slumped down the slope
of the shelf region.
5) Scripps Canyon is a shallow marine canyon in the Pacific Off La Jolla, in California. The valleys
are 12m deep. The maximum depth goes upto 300m. Due to its shallowness and closer to the
Scripps Institution of Oceanography, it has been thoroughly studied.
6) Zhemchug Canyon is a giant underwater canyon located in the middle of the Bering Sea. This
submarine canyon is the largest canyon in the ocean. The canyon has a vertical relief of 2600
meters dropping from the shallow shelf the Bering Sea to the depths of the Aleutian Basin.
Zhemchug Canyon is deeper than the Grand Canyon. Zhemchug Canyon has two main branches,
each larger than typical continental margin canyons such as the Monterey Canyon.
What makes the Zhemchug Canyon the largest canyon in the world is not only its great depth, but its large
cross-sectional area.
Zhemchug Canyon is the largest submarine canyon in the world, based on drainage area (11,350 km2
) and
volume (5800 km3
).
Zhemchug Canyon is important habitat for many species of ocean wildlife.
Submarine Canyons of the Atlantic Ocean:
The Atlantic ocean has the following major submarine canyons:
1) Amazon canyon
2) Hudson canyon
3) Veracruz Canyon.
4) Congo Canyon
5) Great Bahama Canyon.
1) The Amazon Canyon is a submarine canyon within the Amazon Fan in the Atlantic Ocean. It is
located approximately 322 km from the mouth of the Amazon River, near South America. It
covers an area of 2,250 km2
. It was formed in the mid to late Miocene period. The canyon is
believed to have formed through mass failures, and subsequently evolved through underwater
erosion. Because of its relatively small size, the canyon has been extensively mapped.
2) The Hudson canyon is another large submarine canyon incised into the Atlantic Continental slope
and outer shelf off New York Harbour, U.S.A. It is extended from the Hudson river. The

10. 9
canyon is about 80km long with its fan goes to a depth of 3000m. It’s a conduit for moving
sediments, nutrients, and pollution from the land to the deep ocean. Hudson Canyon is a
pathway from land to sea, extending over 400 nautical miles seaward from the New York/New
Jersey harbor, across the continental margin, and out to the deep ocean basin extending 300 miles
beneath the sea. The canyon was formed during the last Ice Age, over 10,000 years ago, when
the sea level was about 121.9 m lower and the mouth of the Hudson River was near the edge of
the continental shelf, about 160.9 km east of its present site. The river discharged sediment that
helped carve the canyon aided by underwater avalanches of mud and sand.
3) The Veracruz Canyon is an underwater canyon located off the eastern coast of Mexico in the Gulf
of Mexico not far from the port city of Veracruz. It is considered for drilling to obtain oil in and
around Veracruz Canyon.
4) Congo Canyon, a large submarine canyon incised into the South Atlantic continental shelf and
slope of equatorial Africa. The head of the canyon lies 28km inland, up the Congo Estuary. It has
a depth of 21m. The canyon crosses the entire shelf for 85km offshore. It cuts across the
continental slope and goes upto a depth of 2650m.
5) Great Bahama Canyon is located off the Bahamas, in the Atlantic Ocean. It lies northeast of the
Great Bahama between Great Abaco and Eleuthera Islands. Two main branches merge to form
the submarine canyon. The vertical wall of the canyon goes upto 4285m from the canyon bed to
the surrounding sea bed. It is 225 km in length.
Submarine canyons of the Indian Ocean:
Indian ocean has a few notable submarine canyons. They include:
1) The Perth Canyon
2) Swatch-of-No-Ground (SoNG)
1) The Perth Canyon is a submarine canyon located on the edge of the continental shelf off the coast
of Fremantle, Western Australia. It is located at approximately 22 kilometres west of Rottnest
Island. It was carved by the Swan River, probably before the Tertiary, when this part of the
continental shelf was above sea level. It is an average of 1.5 kilometres deep and
15 kilometresacross, making it similar in dimension to the Grand Canyon. It occupies an area of
2,900 square kilometres and ranges in depth from 700 to 4,000 metres. Within a few kilometers,
its depth drops from 200 metres down to 1,000 metres, and then it continues as a deep gully all
the way out to the 4,000-metre depth. It contains the world’s largest plunge pool – a depression in
the canyon which is 2 kilometres long, 6 kilometres across, and 300 metres deep.
2) The Swatch-of-No-Ground (SoNG) is a submarine canyon in the northern Indian Ocean. It
supports a fairly well described group of fauna that includes one of the world’s largest known
populations of Indo-Pacific bottlenose dolphins , a possibly resident population of Bryde’s
whales , and large groups of spinner and pantropical spotted dolphins. The distribution of these
species is stratified according to environmental characteristics, with Bryde’s whales and
bottlenose dolphins concentrated in relatively shallow waters close to the canyon head where
upwelling is maximized
CONCLUSION:
Submarine canyons are believed to contain vast reserves of methane hydrates, a promising clean-burning
natural energy source believed to reside in near freezing temperatures under high pressures within sea
floor sediments, although no technology yet exists to extract the methane.
These methane deposits are dispersed under the ocean floor over millions of square miles in this and other
areas of the world.
Some scientists speculate that the methane gas pockets in the underwater shelves could cause undersea
landslides that might produce tsunamis.

11. 10
Physical and biological processes that are common in submarine canyons are mass wasting, turbidity
currents, bottom currents, and bioerosion, mass wasting and turbidity currents being the more important.
Submarine Canyons support a fairly well described group of fauna that includes one of the world’s largest
known populations. The distribution of these species is stratified according to environmental
characteristics.
Marine geology originally focused on marine sedimentation and the interpretation of bottom samples. The
advent of the concept of seafloor spreading, has broadened its scope.
Many investigations of the oceanic ridge system,
the magnetism of rocks on the seafloor,
geochemical analyses of deep brine pools, and
seafloor spreading and continental drift
may be considered within the general realm of marine geology.

12. 11
Perspective view of Los Angeles margin bathymetry looking toward the northeast showing submarine
canyons, U.S. Pacific Continental margin. Note side-by-side occurrence of sinuous San Gabriel Canyon
and braided Newport Canyon near the shelf edge. Vertical exaggeration is 6×. MT = mass transport or
mass wasting (for example, slides, slumps, and debris flows). (U.S. Geological Survey)
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