The scientists determined that the depression was a volcanic vent, and the bright ring around it was pyroclastic, remnants of lava that had been spewed outward, much like a volcanic fountain on Earth.

• 科学家确定凹陷处是一个火山口，并且在它附近明亮的圆环是火山碎屑岩，是火山喷发出岩浆的残余，很象地球上的火山喷口。