text: what is a jetty - how does it differ from a dock?   a jetty is something that is natural... like earth or rock's that strech out into the water where a dock is man made. a great well known piece of art is spiral jetty by: robert smithson a very cool earthwork's artist that has a piece of his art in the great salt lake of utah.  http://www.robertsmithson.com/earthworks/spiral_jetty.htm