Penitentes are dazzling natural-forming ice columns, or more accurately ice blades, that stick up at sharp angles towards the sun. Rarely found except at high altitudes, they can grow taller than a human and form in vast fields.
The following 4 photos were taken by me in Jan 2009 on a mountain slope somewhere between "Plaza Argentina" base camp and high-camp 1, in Argentina's Mt Aconcagua - highest mountain in South America.
First, an entire slope of penitentes with a trail through it
On the slope now
More of the tall penitentes
For more pictures on my Aconcagua climb, visit: http://mntviews.blogspot.com/2009/01/2009-jan-argentina-aconcagua.html