The researchers studied how the coastline of Guichen Bay in South Australia has changed over time. They used aerial photos and ground-penetrating radar to look at the layers of sediment that make up the beach ridges. They found that the beach has been growing outward into the ocean, but the rate of growth has slowed down over time. This is because the beach is reaching deeper water, so it needs more sediment to keep growing. The amount of sediment added to the beach has stayed consistent, even though the rate of growth has decreased. This shows that the beach is filling up with sediment at a steady pace.