The Floor of Eos Chasma (edm - Natural Colors; credits: Lunar Explorer Italia)

An Eroded Crater exposes compositional differences below the Surface: the bluish tones are probably fresher, boulder-rich exposures of Basalt and the lighter-toned material near the base of the crater wall may have a different composition.
The bottom of the crater is filled with material that is similarly-toned to the Surface of Eos Chasma, and was likely eroded and transported there by the wind.