A Scottish lass, Kirsty Millican who wrote a thesis on the subject....

https://ponderingthepast.wordpress.com/2018/07/15/in-praise-of-cropmarks/

When we lived in Chelmsford, I remember looking out on the green in front of the house and seeing circles of a darker green grass, and we were'nt too far away from a neolithic cursus, it is just there like turning the pages of a history book.

http://www.themodernantiquarian.com/site/4252/springfield_barnes_cursus.html