What is a submarine canyon?

A submarine canyon is a steep-sided valley that cuts into the continental slopes and rises of the oceans. They resemble canyons formed by rivers on land and are typically V-shaped with rocky walls that can be thousands of meters high. These canyons act as conduits, transporting sand-sized sediments from continental margins to the deep sea. Many submarine canyons have tributaries at their heads but not as many in their lower courses. The principal agents responsible for their formation are marine processes, notably the erosion and transportation of sediments by turbidity currents. Some are associated with present rivers, like the Hudson Canyon off New York City.

Where are submarine canyons usually found?

Submarine canyons are narrow, steep-sided valleys that cut into the continental slopes and continental rises of the oceans. They can start within continental slopes or on a continental shelf. Unlike deep-sea trenches, which form when one tectonic plate slides beneath another, submarine canyons are found along most continental margins, as well as the slopes of the Hawaiian Islands and possibly other ocean islands. They are rare on continental margins that have extremely steep continental slopes or escarpments.

How are submarine canyons formed?

Submarine canyons are steep-sided valleys that cut into continental slopes and rises, resembling land canyons but with steeper slopes and narrower floors. Their formation has been debated, but the prevailing theory suggests subaerial erosion started the process, specifically during the Pleistocene Epoch's glacial periods when sea levels were lower. However, subaerial erosion alone couldn't have created the deep canyons seen today. Marine processes, especially turbidity currents that erode and transport sediments, are considered the primary agents responsible for their formation. These currents are often triggered by slumping rock material near the canyon heads.

What types of materials are often found inside submarine canyons?

Submarine canyons typically contain a variety of materials, acting as conduits that transport sediments from continental margins to the deep sea. Common materials found inside submarine canyons: Sediments Submarine canyons carry sand-sized sediments from continental margins to the deep sea. Sand and mud During low sea levels, rivers empty directly into the heads of canyons, carrying sand and mud. Shelf molluscan fragments Core samples from abyssal plains contain shelf molluscan fragments carried through submarine canyon systems. Turbidites Deposits from turbidity currents, often consisting of sands and silts, with some containing gravels, can be found in submarine canyons. Hemipelagic sediments Sediments deposited on continental shelves and rises accumulate rapidly. Marine Organisms The remains of both shallow-water and deep-water marine organisms can be found in these deposits.

How do submarine canyons affect ocean currents and marine life?

Submarine canyons are steep-sided valleys that cut into continental slopes, acting as conduits that transport sediments from continental margins to the deep sea. These canyons influence ocean currents by guiding and accelerating them, which can affect sediment distribution and nutrient availability. They also play a vital role in supporting marine life, creating unique habitats and serving as feeding grounds for diverse species. The movement of water and sediment through these canyons can impact the distribution and abundance of organisms, contributing to the overall biodiversity of the marine environment.

Why are submarine canyons important for scientific research and ocean exploration?

Submarine canyons are vital to scientific research and ocean exploration because they act as conduits, transporting sediments from continental margins to the deep sea. The study of the seafloor, including canyons, allows geological processes to be seen more clearly than on land due to the lack of weathering and erosion. These undisturbed sediments hold a historical record of past climates and the state of the ocean. Researchers use acoustic signals, explosives, and gravity and magnetic fields to examine the seafloor and its underlying structure. Sampling equipment such as dredges and coring devices help collect materials for examination.

submarine canyon

Introduction References & Edit History Related Topics

Images

Diagram showing the transition from land to deep ocean, with labeled features including coastal plain, shoreline, continental shelf, continental slope, submarine canyon, seamounts, continental rise, and abyssal plain, illustrating the structure of the continental margin.

Diagram showing the physiographic divisions of the continental margin, including labeled features such as coastal plain, shoreline, continental shelf, continental slope, continental rise, submarine canyon, and abyssal plain.

At a Glance

submarine canyon summary

Quick Facts

Key People:: Francis P. Shepard

Related Topics:: canyon

See all related content

continental margin The broad, gentle pitch of the continental shelf gives way to the relatively steep continental slope. The more gradual transition to the abyssal plain is a sediment-filled region called the continental rise. The continental shelf, slope, and rise are collectively called the continental margin.

submarine canyon

geology

Written and fact-checked by

Britannica Editors

History

Top Questions

What is a submarine canyon?
A submarine canyon is a steep-sided valley that cuts into the continental slopes and rises of the oceans. They resemble canyons formed by rivers on land and are typically V-shaped with rocky walls that can be thousands of meters high.

These canyons act as conduits, transporting sand-sized sediments from continental margins to the deep sea. Many submarine canyons have tributaries at their heads but not as many in their lower courses. The principal agents responsible for their formation are marine processes, notably the erosion and transportation of sediments by turbidity currents. Some are associated with present rivers, like the Hudson Canyon off New York City.
2 Britannica Sources
1. canyon
2. submarine canyon
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Where are submarine canyons usually found?
Submarine canyons are narrow, steep-sided valleys that cut into the continental slopes and continental rises of the oceans. They can start within continental slopes or on a continental shelf. Unlike deep-sea trenches, which form when one tectonic plate slides beneath another, submarine canyons are found along most continental margins, as well as the slopes of the Hawaiian Islands and possibly other ocean islands. They are rare on continental margins that have extremely steep continental slopes or escarpments.
2 Britannica Sources
1. canyon
2. submarine canyon
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How are submarine canyons formed?
Submarine canyons are steep-sided valleys that cut into continental slopes and rises, resembling land canyons but with steeper slopes and narrower floors. Their formation has been debated, but the prevailing theory suggests subaerial erosion started the process, specifically during the Pleistocene Epoch's glacial periods when sea levels were lower.

However, subaerial erosion alone couldn't have created the deep canyons seen today. Marine processes, especially turbidity currents that erode and transport sediments, are considered the primary agents responsible for their formation. These currents are often triggered by slumping rock material near the canyon heads.
2 Britannica Sources
1. canyon
2. submarine canyon
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What types of materials are often found inside submarine canyons?
Submarine canyons typically contain a variety of materials, acting as conduits that transport sediments from continental margins to the deep sea.

Common materials found inside submarine canyons:
- Sediments Submarine canyons carry sand-sized sediments from continental margins to the deep sea.
- Sand and mud During low sea levels, rivers empty directly into the heads of canyons, carrying sand and mud.
- Shelf molluscan fragments Core samples from abyssal plains contain shelf molluscan fragments carried through submarine canyon systems.
- Turbidites Deposits from turbidity currents, often consisting of sands and silts, with some containing gravels, can be found in submarine canyons.
- Hemipelagic sediments Sediments deposited on continental shelves and rises accumulate rapidly.
- Marine Organisms The remains of both shallow-water and deep-water marine organisms can be found in these deposits.
5 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How do submarine canyons affect ocean currents and marine life?
Submarine canyons are steep-sided valleys that cut into continental slopes, acting as conduits that transport sediments from continental margins to the deep sea. These canyons influence ocean currents by guiding and accelerating them, which can affect sediment distribution and nutrient availability. They also play a vital role in supporting marine life, creating unique habitats and serving as feeding grounds for diverse species. The movement of water and sediment through these canyons can impact the distribution and abundance of organisms, contributing to the overall biodiversity of the marine environment.
2 Britannica Sources
1. canyon
2. submarine canyon
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Why are submarine canyons important for scientific research and ocean exploration?
Submarine canyons are vital to scientific research and ocean exploration because they act as conduits, transporting sediments from continental margins to the deep sea. The study of the seafloor, including canyons, allows geological processes to be seen more clearly than on land due to the lack of weathering and erosion. These undisturbed sediments hold a historical record of past climates and the state of the ocean. Researchers use acoustic signals, explosives, and gravity and magnetic fields to examine the seafloor and its underlying structure. Sampling equipment such as dredges and coring devices help collect materials for examination.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

submarine canyon, any of a class of narrow steep-sided valleys that cut into continental slopes and continental rises of the oceans. Submarine canyons originate either within continental slopes or on a continental shelf. They are rare on continental margins that have extremely steep continental slopes or escarpments. Submarine canyons are so called because they resemble canyons made by rivers on land.

Unlike deep-sea trenches, which are found in areas where one tectonic plate slides beneath another, undersea canyons are found along the slopes of most continental margins. They also occur along the slopes of the Hawaiian Islands and possibly certain other ocean islands. The majority of these V-shaped depressions have steep, rocky walls thousands of metres high. Those of the Grand Bahama Canyon, which are thought to be the highest, rise nearly 5 km (3 miles) from the canyon floor. The walls of the Grand Canyon of the Colorado River, by comparison, measure about 1.6 km (1 mile) high. Most submarine canyons extend only about 48 km (30 miles) or less in length, but a few are more than 320 km (200 miles) long. They usually are many kilometres in width; for instance, the Grand Bahama Canyon measures 37 km (23 miles) at its widest point.

A relatively large number of submarine canyons are located directly offshore of river canyons of adjacent land areas and may have once been connected to extensions of the latter. In most cases, however, the characteristics of the submarine variety and those of the nearby land canyons are quite distinct. The submarine canyons, for example, tend to have steeper side slopes, much higher gradients, and considerably narrower floors. Moreover, the drainage pattern of submarine canyons differs from that of their terrestrial counterparts. The submarine canyons have a substantial number of tributaries at their heads but generally do not have as many tributaries in their lower courses as do the land canyons. Even so, many submarine canyons end in a series of distributary channels through the continental rise, and these channels often emerge in the deep sea on abyssal plains that are found adjacent to the continents, especially in the Atlantic basin.

Submarine canyons act as conduits to bring sand-sized sediments from the continental margins to the deep sea. During lowstands of sea level, rivers empty directly into the heads of many Atlantic canyons. Sand and mud are carried down these systems, many times bypassing the slope-rise system to be carried directly out onto the abyssal plains of the ocean floor. Core samples taken in abyssal plains in the Atlantic Ocean off North Carolina show distinctive shelf molluscan fragments in gravity-flow deposits that have traveled hundreds of kilometres and that can be traced back through the Hatteras submarine canyon system. During highstands of sea level, the submarine canyons off the east coast of North America are many tens of kilometres from the coastline, and the downslope movement through them is slowed down dramatically or perhaps even ceases. On the west coast of the continent, where active tectonism results in a narrow margin backed by high mountains, a situation exists today that is roughly analogous to the one that prevails on a passive margin during lowstands of sea level. Submarine canyons originate close to the coast, intersecting the longshore current system and siphoning off sand to basin floors in the Borderland—that is, the continental margin of southern California and northern Baja California.

For years the origin of submarine canyons has been the subject of much debate among investigators. Various ideas have been proposed, but prevailing theory favours subaerial erosion as the starting point for a good number of undersea canyons. Such erosion is thought to have begun with the lowering of sea level during the glaciations of the Pleistocene Epoch (about 2,600,000 to 11,700 years ago). It is perceived, however, that subaerial erosion alone could scarcely have excavated deep canyons that extend down to the seafloor. Evidence seems to suggest that the principal agents responsible for the formation of submarine canyons are marine processes, most notably the erosion and transportation of sediments by turbidity currents activated by the slumping of unconsolidated rock material near the heads of the canyons.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by John P. Rafferty.