Mars Home to Ancient Lakes Sat. A topography profile of the Gale Crater, along with an image of the central mound stratigraphy.
Massive units appear as one bulky rock layer with no clearly defined horizontal bedding.
In a few cases, these types appear together, with the massive unit always perched on top of the bedded unit. Thin mesa units, with surfaces ranging from smooth to pitted, to ridged and grooved, are almost always found on top of eroded massive or layered sedimentary rock. A paper on the images will appear in this Friday's issue of the journal Science . The findings were to be reported at a NASA news conference Thursday, after an embargo on the information lifted. That embargo was lifted today, after other news organizations published accounts of the study.