Glacier Landforms

Wave Erosion Shorelines are being constantly eroded by waves, tides, and chemical weathering. Sea cliffs are produced by wave erosion. Resistant rock areas that project from the shore are called headlands. Rock platforms beneath the water are called terraces, and are either built up by waves depositing sediment, our are made by the erosion of the stone on top of them.

Beaches A beach is a deposit of any kind of sand or rock fragments along a shoreline. Most beaches have a raised section called the berm, caused by waves, and sand bars, which are collections of sand, formed underwater.

Longshore Currents Water moving along the shore are longshore currents, a current parallel to the shoreline. A long, narrow deposit of sand connected at one end to the shore is called a spit. A ridge of sand connected an offshore island to the mainland is called a tombolos.

Coastlines Sea levels are constantly changing, such as during the last ice age, where sea levels were 140 m lower than today, and coastlines were drastically different. The tectonics of the earth also change coastlines, especially along plate boundaries.

Submergent Coastlines When the sea level rises, or the land sinks, the previous coastline is submerged. Beaches will begin to form, valleys become bays and inlets, and high points on submerged land become islands. Estuaries, a river opening where fresh and salt water mix, often form when this occurs.

Emergent Coastline The opposite also occurs. When the sea level falls, the previously submerged land becomes an emergent coastline.

Barrier Islands Barrier Islands are long, narrow ridges of sand, over 100 km long, parallel to the coastline, somewhere between 3 to 30 km offshore. The area between the shore and the barrier island is called a lagoon.

Coral Reefs Fringing Reef: A coral reef around the coast of an island. Barrier Reef: A reef around the remnants of a volcanic island, much farther away from land. Atoll: A reef surrounded a completely submerged island.