I want to point readers to the (virgin) plains which have been far from man-made structures, without any changes over the years. In its original Persian version, for virgin I used an adjective which is only used for humans and horses! But I do not know whether or not it makes sense in English to do the same. Surely virgin has many equivalent meanings in Persian like noble, original and gentle not only the meaning on ground of having sex or not.
There are some similar compositions like: virgin prairies, noble plains & noble prairies.
Please write me which of above is best for the purpose mentioned; and if you have a better term I would be grateful to know it.