Legal standing of easement only shown on an unrecorded plat

I wanted to add that any document that is called in a deed is as much a part of that deed as if it was copied into the deed.

However, don't mix up a "public" easement that may need to be recorded and accepted by the public body with an easement that benefits other owners in a subdivision. And no dates were given, so maybe the unrecorded subdivision was done before there were recording laws for subdivisions. Laws that require recordation of subdivisions and easements don't invalidate previous subdivisions and easements.