Cup marks are manmade:

http://en.wikipedia.org/wiki/Cup_and_ring_mark

http://www.window2baku.com/eng/Ancient/9cupmarks.htm

http://www.stonepages.com/news/archives/003233.html

http://azer.com/aiweb/categories/magazine/ai111_folder/111_articles/111_cart_ruts.html

http://www.pasthorizons.com/index.php/archives/11/2010/standing-stone-cup-marks-may-represent-star-constellations