Pit Chain on Arsia Mons - "Annie" (EDM - Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)

Caption NASA:"This small Pit located in the middle of the Chain was discovered by a team of scientists from the U.S. Geological Survey and Arizona State University using data from the THEMIS camera onboard the Mars Odyssey Spacecraft during a search for possible Cave Entrances. They informally named this pit "Annie".
A section of the HiRISE image over "Annie" has been specially processed to enhance the contrast in the shadowed areas. This shows that the Pit is is largely filled with wind blown materials. Shadow measurements indicate that the Floor is about 112 meters (367 feet) below the Rim".