a geologist points excitedly at distinct horizontal bands of different colored rock layers visible in the cliff wall. She uses a magnifying glass to examine the clearly separated bands of gray, brown, and reddish stone. The exposed rock face reveals multiple distinct layers stacked on top of each other from different time periods. Her research partner takes detailed notes while looking at the same layered rock formation. Other team members gather around with tools, all focused on studying the visible rock layers. multiple layers or series of layers of rock in the ground