1. Plural of alluvium; fine sediment (clay, silt, sand) deposited by flowing water, especially in river valleys and deltas.
Usage: technical/geological; plural form

Examples

• The river deposited rich alluvia across the floodplain each spring.
• Geologists studied the layers of alluvia to understand the region's ancient climate.
• The fertile soil in the delta consists mainly of alluvia from upstream erosion.
• Archaeologists found pottery shards buried in the alluvia near the riverbed.
• The alluvia in this valley indicate centuries of water flow and deposition.