"Re: interesting Martian photos
Posted by Jonathon (206.146.129.38) on 2/7/2002 5:40:18 AM
In Reply to: Re: interesting Martian photos posted by Robert Clark on 2/6/2002 11:09:41 PM
Bob, the comparision photos you provided have two different origins by their make up. The Mars photo in question have valleys carved into the surface while the other comparision photos are dried cracked surfaces or areas of ice melt "wedging". It Mars photo appears as one would see in strip mining techniques. Also there are two faint horizontal lines extending from top to bottom on the image. I'm not sure if this is on the surface of Mars or an image processing defect."
http://www.habitablezone.com/space/messages/17716.html

Ice-wedge polygons can be of either high-centered or low-centered type. The landforms in the "Inca city":

Mars Orbiter Camera (MOC) High Resolution Images:
Rectilinear Ridges In South Polar Layered Terrain ("Inca City")
http://www.msss.com/mars_images/moc/science_paper/f5/

are perhaps of the low-centered type:

Frozen ground in the Arctic
http://www.mapcruzin.com/arctic_refuge/permpics.html

This report discusses polygons of both types on pages 10 - 15 by the PDF page numbering and mentions on page 20 that one type can transform into the other:

GUIDEBOOK TO PERMAFROST AND RELATED FEATURES
OF THE COLVILLE RIVER DELTA, ALASKA
http://wwwdggs.dnr.state.ak.us/scan1/gb/text/GB2.PDF

Bob Clark