a few years ago my son and his best friend, who were about 8 at the time, constructed a sculpture in my driveway from large smooth stones, bricks, and cement blocks. i loved that sculpture both for the sponteneity they exibited while building it and the artistic expression of two little boys.
so when i ran across escher's flickr stream (richard shilling) it became one of my frequent stops. he makes art from nature in the vein of andy goldsworthy and is a talent in his own right.
you can get to the flickr photos of his work at http://www.flickr.com/people/escher1/
it's a destination well worth checking out, as is his blog at www.jrlandart.blogspot.com.
richard also has a book titled "land art." i will definitely be putting this on my wish list!
Land Art by Richard Shilling
enjoy! and while you are at flickr, don't forget to take a look at my photos there, too! http://www.flickr.com/photos/paperwerks/