This fascinating icy plains region -- resembling frozen mud cracks
on Earth -- has been informally named "Sputnik Planum" (Sputnik Plain) after the Earth's first artificial satellite.
Mud cracks on the top of the muddy limestone and large-scale erosional features (Fig.
5), as demonstrated by mud cracks and palaeokarst surface above the second unit.
The team believes that thermal fracture and desiccation fracture (formed like mud cracks
in a dry lake bed) may be launching small dust particles that are then picked up by sunlight and pushed into the tail.
2 billion-year-old mud cracks
, 800-million-year old algal reefs, and 270-million-year-old fossils.
Above the basal conglomerate of the Tapeats, the rest of the formation is composed of sand about 200 feet thick, with bedding containing sedimentary structures typical of tidal flat, beach, and shallow-shore environments that include ripple marks, mud cracks, and raindrop prints (Fig.
Mud cracks are sedimentary structures that form by the shrinkage of wet mud when it dries out.
Ripple marks and mud cracks are preserved in the Precambrian Bass, Hakatai, Dox, and Nankoweap Formations.
The fractures resemble mud cracks
on Earth, which form when water-soaked soil dries and contracts, notes rover researcher John Grotzinger of the Massachusetts Institute of Technology.
The parched mud cracks
, and the top layers turn black and shrivel like burned bacon.
Fossilized rippling and evidence of mud cracks
indicate that over 100 million years ago the river, in what is now China's Szechuan Province, went through dry and wet cycles.