A sediment layer is one band of silt, sand or mud in rock. Count the sediment layers.
Each marks material that settled at a particular time, so the sequence is a calendar. A sediment layer of ash or iridium can date a single catastrophic year across the world.
1nounsediment layerOne band of silt, sand or mud in rock, marking material that settled at a particular time.
“The pale sediment layer was volcanic ash from one eruption.”
sediment layer is a layer.
Practised in Dinosaurs & Prehistory