How did the Cluilian Trenches survive so long?

[Onasander]

trench:http://en.m.wikipedia.org/wiki/Cluilian_trench

 

I dont know of any trenches around here that lasted two centuries.... roads cut into bedrock, yeah, but not like, old trenches. For those in Europe, how have the old WW1 trenches held up? I can find old horse trails in the woods here in north America, but they are fading fast from erosion. Every fort from 200 years ago, of wood and dirt, long gone.

[Pompieus]

Traces of trenches on the battlefields of the American Civil War survive 150 years later at Wilderness, Spotsylvania and Petersburg.  Carefully preserved by the War and Interior departments of course.

[caldrail]

You can see defensive earthworks all over southern Engkland, some dating from the early Iron Age. A little eroded perhaps, but unmistakeable.

[Onasander]

Are you talking about those hugh Motte and Bailey mounds? Im talking ditches.

[Bryaxis Hecatee]

you can still see the ditches surrounding Stonehenge when you visit the place and look around you while going to the monument, instead of only starring at it. As for WW1 trenches, you can of course still see them even at ground level, although a lot was backfiled and is thus only visible from the sky. You can actually see individual artillery shell holes from the sky all along the fronts of WW1. You also have various other ditches that can be seen in many other places, including some from the roman time : think of the Antonine wall for exemple. 

 

Another typical kind of ditch is the surface iron mining ditches from the iron age you can often find in the forests of France or central Europe.