The deltas suggest a river transported clay minerals into the basin from a watershed.
Because of abundant solar ultraviolet radiation at the surface, organic molecules might not be preserved as well as clay minerals.
The next step is to try to staunch the flow proper with drilling mud, a mixture of water and clay minerals.
They're layered and their composition is consistent with clay minerals being present.
But here's the catch: Clay minerals are easily dissolved in acidic water.
The clay minerals must have been formed at relatively low temperatures.
The scientists said the locale was almost certainly a primordial lake bed, rich in clay minerals, where the water many eons ago wasn't too salty or alkaline for life to thrive.
Armed with more sophisticated analysis tools than earlier rover teams, Curiosity scientists have been able to conclusively find the first on-the-ground evidence for the presence of abundant clay minerals within those drilled rocks.
Observations from orbit have identified clay and sulfate minerals in the lower layers, indicating a wet history.
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On thermal satellite images, the soil here seemed to retain its heat unusually well a sign that it might contain clay or other hydrated minerals.
Using filters on the rover's Mast camera (Mastcam) and an instrument which shoots neutrons into the ground to probe for hydrogen, researchers have detected more hydrated minerals near the clay-bearing rock than at locations Curiosity visited earlier in its mission.
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Such helium was found inside fullerenes in well-studied, clay sediments that contain extraterrestrial iridium and highly shocked minerals resulting from an asteroid impact 65 million years ago.
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