Earthworks were constructed in a great variety of forms depending upon their functions. Provisional earthworks, constructed for long term occupation, can be highly engineered, complex geometric forms with several lines of defense. At the other end of the spectrum are hasty entrenchments. These can be a single line of works along the crest of a hill, or a rifle pit used by a single soldier. The primary threat to earthworks is erosion.
Erosion is the movement of soil from one location to another, by water, wind, or gravity.
This can be detrimental to earthworks in two ways. Besides reducing the size of and destroying the form of parapet walls, erosion can also fill in and obscure trenches. Most erosion is caused when the vegetation which serves to hold soil in place is damaged or removed. This can be caused by both natural phenomena and human impacts. These impacts can effect earthworks existing under different conditions in different ways.