Trench

A trench is a type of excavation or depression in the ground. A trench is generally defined by being deeper than it is wide (as opposed to a wider gully or ditch), and by being narrow compared to its length (as opposed to a simple hole).^[1]

Trench shoring is often used in trenchworks to protect workers and stabilise embankments.

Types and uses of trenches

Geology

Some trenches are created as a result of erosion by rivers (which may have long since become dry), others are created by geological movement of tectonic plates, such as rift valleys or more commonly oceanic trenches. Some oceanic trenches include the Mariana Trench and the Challenger Deep. The latter form is relatively deep (ca. 10 km), linear and tiny, and is formed by plate subduction when plates converge.^[2]

Construction

In the civil engineering field of construction or maintenance of infrastructure, trenches play a major role. They may be created to search for pipes and other infrastructure that is known to be underground in the general area, but whose exact location has been lost ('search trench' or 'search slit'). They are also used to place underground easily damaged and obstructive infrastructure or utilities (such as gas mains, water mains or telephone lines). A similar use for higher bulk would be in pipeline transport. Finally, trenches may be created as the first step of creating a foundation wall.

Military

Soldiers in a trench during the Gallipoli Campaign of World War I

Trenches have often been dug for defensive purposes. In the pre-firearm eras, they were mainly a type of hindrance to an attacker of a fortified location, such as the moat around a castle (this is technically called a ditch). An early example of this can be seen in the Battle of the Trench.

With the advent of accurate firearms, trenches were used to shelter troops. Trench warfare and tactics evolved further in the Crimean War and World War I, until systems of extensive main trenches, backup trenches (in case the first lines were overrun) and communication trenches often stretched dozens of kilometres along a front without interruption, and some kilometres further back from the front line.

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Archaeology

The "trench method" is used for searching and excavating ancient ruins or to dig into strata of sedimented material to get a sideways (layered) view of the deposits – with a hope of being able to place found objects or materials in a chronological order. The advantage of this method is that it destroys only a small part of the site (those areas where the trenches, often arranged in a grid pattern, are located). However, this method also has the disadvantage of only revealing small slices of the whole volume, and modern archeological digs usually employ combination methods.^[3]

References

^ Code of Federal Regulations, Title 29, Volume 8, Page 374 (Code revised as of July 1, 2003, via Compliance Magazine's website)^{[dead link]}
^ Ocean trench (glossary from Student Resource Center website, Houghton Mifflin college division)
^ Archaeology – People! Magazine, Winter 1998

External links

Trenching and Excavation (a NIOSH Safety and Health Topic, Centers for Disease Control and Prevention)
Trench Safety Awareness (a NIOSH Publication, Centers for Disease Control and Prevention)

[1] Code of Federal Regulations, Title 29, Volume 8, Page 374 (Code revised as of July 1, 2003, via Compliance Magazine's website)^{[dead link]}

[2] Ocean trench (glossary from Student Resource Center website, Houghton Mifflin college division)

[3] Archaeology – People! Magazine, Winter 1998

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