Interesting!
However, I've also found lots of apparent modern "aimless dirt moving" -- including a 3.5 mile long curving "dirt ridge", with regularly-spaced spoil dirt dump piles aligned on top of it. Only thing I can think of is an attempt at an earthen-fill dam -- in a place with no water...
If any of you do manage to locate some of these "gates", please ping me -- and include the Google Earth coordinates. Thanks!