| || | 30 Jan 2008 Layering and Slope Streaks in Henry Crater
Named after a 19th century French astronomer, Henry Crater is a
165 kilometer (103 mile) diameter impact crater, located in
Arabia Terra on a portion of the Martian highlands extending
into the northern hemisphere. This observation shows multiple
layers on the edge of a mound on the floor of the crater, which
is distinct from others in the immediate vicinity. The layers
represent the eroded remains of sedimentary rocks that formed
from sediments deposited within the crater sometime after its
formation. The origin of the sediments on the crater floor in
not known but may be windblown dust and sand. The layers exhibit
differences in degrees of hardness and resistance to erosion
with resistant layers forming cliffs and more easily eroded
layers forming ledges. Several dark streaks are visible on
slopes (see subimage). Slope streak formation is among the few
known processes currently active on Mars. Streaks are believed
to form by downslope movement of