Charlie, the quote below is direct from the page "About This Gallery" whose link is at the top of the Landscape Gallery page...
"NPN's Earth, Sea & Sky™ landscape image critique gallery is dedicated to photos of natural landscapes, seascapes, and celestial images showing no evidence of hand-of-man."
So, to answer your question directly: The answer is no, there no guideline for the amount of 'land' for an image in the gallery.
Discussion
3 replies"NPN's Earth, Sea & Sky™ landscape image critique gallery is dedicated to photos of natural landscapes, seascapes, and celestial images showing no evidence of hand-of-man."
So, to answer your question directly: The answer is no, there no guideline for the amount of 'land' for an image in the gallery.
--P
Sandy
Charlie