How can changes in sea level create raised marine terraces?

A marine terrace is a rock terrace that forms when a wave-cut platform—a gently sloping ledge eroded by wave abrasion at the base of a sea cliff—is raised above sea level.12

This process occurs when the relative position of the sea and the land changes, effectively ending the active wave erosion that originally created the platform. These features can be created through two primary mechanisms:2

• Coastal Uplift: Tectonic activity can physically raise a section of the coastline, lifting the wave-cut platform out of the reach of the tides.2
• Sea Level Lowering: A global drop in sea level—often associated with the storage of water in large ice sheets during glaciations—can leave previously submerged platforms exposed above the water line.342

Because these terraces mark former positions of the shoreline, they are valuable geological tools used to calculate the history of coastal uplift or fluctuations in sea level over time. When a coast experiences multiple intermediate stillstands of sea level, it may produce a series of these terraces at different elevations.2