12.13.2016 Now and Long Ago at Gale Crater, Mars
12.13.2016 Where's Boron? Mars Rover Detects It
10.03.2016 Curiosity Self-Portrait at 'Murray Buttes'
10.03.2016 Butte 'M9a' in 'Murray Buttes' on Mars
09.19.2016 Ribbon Cutting
09.09.2016 Farewell to Murray Buttes (Image 5)
09.09.2016 Farewell to Murray Buttes (Image 4)
09.09.2016 Farewell to Murray Buttes (Image 3)
09.09.2016 Farewell to Murray Buttes (Image 2)
09.09.2016 Farewell to Murray Buttes (Image 1)
08.26.2016 Out-of-this-World Records
03.30.2016 Erisa Hines
03.30.2016 Buzz Aldrin
02.12.2016 Women in Science
02.09.2016 Adam Steltzner, a JPL engineer
01.27.2016 Night Close-up of Martian Sand Grains
01.27.2016 Curiosity Self-Portrait at Martian Sand Dune
12.17.2015 Alteration Effects at Gale and Gusev Craters
12.17.2015 Full-Circle View Near 'Marias Pass' on Mars
12.11.2015 Surface Close-up of a Martian Sand Dune
12.11.2015 Martian Sand Disturbed by Rover Wheel
11.24.2015 Carbon Exchange and Loss Processes on Mars
11.17.2015 Chemical Laptop 1
Erosion by Scarp Retreat in Gale Crater (Unannotated)This mosaic of images from the Mast Camera (Mastcam) instrument on NASA's Curiosity Mars rover shows a series of sedimentary deposits in the Glenelg area of Gale Crater, from a perspective in Yellowknife Bay looking toward west-northwest.
Curiosity's science team has estimated that the "Cumberland" rock that the rover drilled for a sample of the Sheepbed mudstone deposit (at lower left in this scene) has been exposed at the surface for only about 80 million years. The estimate is based on amounts of certain gases that accumulate in a rock when it is close enough to the surface to be bombarded by cosmic rays. An explanation for that unexpectedly young exposure age comes from improved understanding of how the layers are eroding to expose underlying layers. The explanation proposes that the mudstone is being exposed by abrasion by windblown sand, indicated by arrows (annotated version). The role for wind is strongly suggested by the undercutting of the Sheepbed layer below the Gillespie Lake sandstone.
The pattern here suggests that the Yellowknife Bay outcrop is being exposed by wind-driven scarp retreat -- the sideways erosion of a vertical face.
Mastcam took the images for this mosaic during the 188th Martian day, or sol, of Curiosity's work on Mars (Feb. 14, 2013). The 100-centimeter scale bars are about 39 inches long. A rock ledge about 8 inches (20 centimeters) high at the bottom of the scene -- where the Gillespie Lake layer meets the Sheepbed layer -- is about 50 feet (about 15 meters) from the rover's location when the images were taken. The midfield escarpment called "Point Lake" is about 118 feet (36 meters) from the rover's location. The outcrop on the near horizon, marked with a white X, is about 43 feet (13 meters) higher in elevation than the Sheepbed-Gillespie contact and at a distance of about 780 feet (240 meters).
The image has been white-balanced to show what the rocks would look like if ther were on Earth.
An annotated version of the image is available.
Image Credit: NASA/JPL-Caltech/MSSS