The Renton Formation is a geologic formation in Washington (state) within the Puget Group. It preserves fossils dating back to the Paleogene period.
“He’s not alone. I hear similar concerns from fellow parents when I’m walking with my friends or at one my kids’ games.”
The [Renton Formation] sandstone is weakly cemented, most commonly with calcite, but in places matrix silt and clay act as the binding agent.
Some beds in the [Renton] formation are very soft and plastic when wet, owing to the weathering or alteration of feldspar to a montmorillonitic clay.