What is a Trench?

Mary McMahon
Mary McMahon

A trench is a long depression in the ground which is deeper than it is wide, with a width which is significantly smaller than its length. Trenches may be constructed artificially for a variety of purposes, and they also occur naturally. Essentially, a trench is an oversized ditch, with some trenches having some extra features.

Ocean trenches are most often located parallel to volcanic islands, at the boundary of two tectonic plates.
Ocean trenches are most often located parallel to volcanic islands, at the boundary of two tectonic plates.

In nature, trenches are most abundant in the ocean, where they are known as ocean trenches. Ocean trenches are formed by the buckling, folding, and spreading of the sea floor, and some of them can get extremely deep. In the case of abyssal trenches like the Mariana Trench, ocean trenches can also sometimes harbor interesting and distinctive animals. Natural trenches on land are formed through a variety of process, in some cases eroding and expanding to turn into valleys and other large natural features.

Trenches are often dug in order to accommodate utility lines.
Trenches are often dug in order to accommodate utility lines.

Humans have been constructing trenches for a variety of purposes for thousands of years. One of the earliest uses of the trench is in fortifications for warfare, as investigations at some archaeological sites have revealed. Trenches have also been utilized in agriculture to transport water for irrigation. Trenches continue to be used for these purposes in many regions of the world. Trenches are also used to make fencing and dividing lines between fields.

Trenches played a prominent role in strategy during the First World War.
Trenches played a prominent role in strategy during the First World War.

Trenches are also sunk for the purpose of installing utilities. Keeping gas, electric, and phone lines underground reduces clutter aboveground, with the earth acting as natural insulation. Utility workers may also sink search trenches to determine the location of utility lines if they aren't exactly sure about where to look. Road workers often sink search trenches to determine the precise location of underground utilities, which is why they periodically tear up chunks of the road, spray paint obscure markings, and then replace the sections again.

One of the earliest uses of trenches was in warfare.
One of the earliest uses of trenches was in warfare.

Archaeologists also utilize trenches in their work. In order to investigate sites in an orderly way, archaeological teams start by sinking a series of shallow trenches, and then work their way slowly down, sifting the soil as they go to look for artifacts. Creating archaeological trenches can be a painstaking process, as the goal is to preserve the site as much as possible while uncovering it and taking notes on the locations where artifacts are found. Many archaeological sites bear the evidence of multiple civilizations which simply built on top of each other, making it critical to keep the layers of a site separate so that the provenance of artifacts is not confused.

Trenches have been utilized in agriculture to transport water for irrigation.
Trenches have been utilized in agriculture to transport water for irrigation.
Flamethrowers were first used by the German army to clear out trenches during World War I.
Flamethrowers were first used by the German army to clear out trenches during World War I.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

claire24

I'm trying to think of ways that natural trenches would be formed on land. Would the trails left by glaciers be considered trenches, or are they too big?

I would think that rivers would be another form of natural trenches. Is this true?

rosoph

I never knew that a trench has to be deeper than it is wide. What is it called if the width and depth are the same?

I also never knew that the ocean is full of trenches. How big do these trenches actually get?

Thank you for sharing all of these interesting facts.

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