Potassium 40 dating rocks
One reason is that mudstone is a sedimentary rock—formed in layers over a span of millions of years from material that eroded off of the crater walls—and thus the age of the sample drilled by Curiosity really represents the combined age of those bits and pieces.Although the potassium-argon method has been used to date rocks on Earth for many decades, these types of measurements require sophisticated lab equipment that could not easily be transported and used on another planet.Farley had the idea of performing the experiment on Mars using the SAM instrument.At 80 million years ago, wind would have caused this scarp to migrate across the surface and the rock below the scarp would have gone from being buried—and safe from cosmic rays—to exposed," Farley explains.
Geologists have developed a relatively well-understood model, called the scarp retreat model, to explain how this type of environment evolves.
Cosmic rays are known to degrade the organic molecules that may be telltale fossils of ancient life.
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