Villaman,

You have created a monster, thanks for the education.

Ok same image as above area A. This is the eruption site. How do I know it is the eruption site? I look at the change I characteristics of the surface material in conjunction with other areas like B.

B. This is a micro-gully. Similar to crater gullies just on a smaller scale. This just happens to extend from the eruption site.

C. Back was pattern from eruption site. The material that was in the hole had to go somewhere and here it is.

http://www.flickr.com/photo_zoom.gne?id=1342229688&size=o

Hope this helps, Darwin