Astrobiology Magazine contacted Dr. Rebecca Williams, lead author of the study, with some additional questions about his research:
Astrobiology Magazine: Is there any other process that could have created these formations? Why is flowing water the most likely explanation?
Williams: The rounded shape of the pebbles is a testament to a transport process, either wind or water. Rocks that exceed a few mm in size are too large to move by wind. The typical pebble size is around 1 cm, and the largest rocks are 4 cm across. Thus, at this size, fluvial transport is the most likely process.
AM: How widespread are these features in the Curiosity landing site? Are they commonly seen in the area that the rover has explored so far?
Williams: We've encountered a half-dozen outcrops of these water-transported conglomerated during our journey across Bradbury Rise. These are patchy occurrences and we are hoping to find more exposures as we travel back across this terrain en route to Mount Sharp. The MSL science team has a number of hypotheses for how these conglomerates relate to other rocks in this area, including the ones we have drilled near Glenelg, and seeing additional conglomerates will help refine our understanding of the overall ancient environment.
AM: Why is the study area named 'Hottah'?
Williams: The MSL science team names rocks and other science targets for ease of reference. Generally the names are for noteworthy geological sites on Earth. At noteworthy sites, we also pay tribute to the memory of individuals who have contributed significantly to the mission.
AM: How can you tell the depth and flow rate of the water that created these features?
Williams: Using what we know about the physics of water flow and the motion of rocks in rivers, we can estimate the minimum water flow conditions required to move rocks of this size on Mars.