While it is slightly off your topic, I was looking for ventifact images the other day, and I came across the following:
First, some fun vocabulary words:
Ventifact: a wind abraded rock,
Einkanter: one polished face
Dreikanter: two polished faces
Zweikanter: two curved faces intersecting at a sharp edge
Here's a cool one, from this page (which has some great pictures of sliding rocks as well):
Antarctica has some great examples, like the pictures at 77DegreesSouth. If we ever see a ventifact like this on Mars, we are going see people going nuts.
<img src="http://huey.colorado.edu/77DegreesSouth_Images/photos%20report%208/11-Ventifact.jpg";
The next one is the kind of thing I'd try to climb to have lunch on (I found it here):
From Operation Neko's photo page is this strange, gouged out ventifact:
From Carol Landis, another weird one:
These are some figures from a pre-MER discussion of wind related features on Mars from the Journal of Geophysical Research.
It is by no means a comprehensive view of odd ventifacts, and while I did not find a nice four sided pyramid, I would not be surprised to see them. I'm not sure from that perspective that that ventifact it is four sided or semi-tetrahedral. Are they (4 sided) more common on Mars than they are on Earth? Hard to do stats from a quick google image search.
I'm reviewing my own slides to see if there is anything as good as these.
But you are right, wind erroded forms are cool!
jms
Space/Science » in reply to Pyramids! Pyramids everywhere on Mars!
Some terrestrial ventifacts: