Earthwork (noun)

A fortification or other construction made of earth, such as a bank, trench, or rampart.

Origin:

From earth + work.

Examples:

1. The ancient city was protected by earthworks.
2. The construction of the earthworks required a lot of manual labor.
3. The earthworks were used for defensive purposes.
4. The earthworks were built to protect the city from invaders.
5. The earthworks were an important part of the city's history.