Mars Astrobiology: Recent Status and Progress - Planetary Exploration and Science: Recent Results and Advances - page 159

Fig. 8.6 The preservation and cementation of aeolian dune stratigraphy in Burns Cliff slope
in Endurance Crater are thought to have been controlled by flow of shallow groundwater. The
layers show different types of deposition of sulfate-rich sediments, with ancient dunes on the
bottom, ancient groundwater on the middle, and ancient water streams on the top of the layers.
Image by the Opportunity rover ( http://photojournal.jpl.nasa.gov/catalog/PIA07110 - NASA/JPL-
Caltech/Cornell University, December 17, 2007)
Others have disputed the strong link between amphitheater heads of valleys and
formation by groundwater for terrestrial examples and have argued that the lack
of fine-scale heads to valley networks is due to their removal by weathering or
impact gardening. Most authors accept that most valley networks are at least partly
influenced and shaped by groundwater seep processes (Fig. 8.6 ).
Groundwater also plays a vital role in controlling broad-scale sedimentation
patterns and processes on Mars. According to this hypothesis, groundwater with
dissolved minerals came to the surface, in and around craters, and helped to form
layers by adding minerals - especially sulfate - and cementing sediments. In other
words, some layers may be formed by groundwater rising up depositing minerals
and cementing existing, loose, aeolian sediments.
The hardened layers are consequently more protected from erosion. This process
may occur instead of layers forming under lakes. A study published in 2011 using
data from the Mars Reconnaissance Orbiter show that the same kinds of sediments
exist in a large area that includes Arabia Terra. It has been argued that areas which
we know from satellite remote sensing are rich in sedimentary rocks are also those
areas which are most likely to experience groundwater upwelling on a regional
scale.