ashfall
/ˈæʃˌfɔl/Definitions
1. noun
the falling or deposit of ash, typically from a volcanic eruption or wildfire
“The town was blanketed with a thick layer of ashfall from the nearby volcano.”
2. noun
a layer or deposit of ash, especially one that has accumulated over a long period
“The archaeologists carefully excavated the ashfall to uncover the ancient city.”