Headlands are characterised by high, breaking waves, rocky shores, intense erosion, and steep sea cliff. Headlands and bays are often found on the same coastline. A bay is flanked by land on three sides, whereas a headland is flanked by water on three sides.
A beach forms when waves deposit sand and gravel along the shoreline. and pebbles. Over time they are worn smooth from being rolled around by waves. The rocks usually reflect the local geology.
flat fertile flood plains. (v) Sand dunes are low hill-like structures formed by the deposition of sand in the deserts. (vi) Beaches are formed when the sea waves deposit sediments along the shores of the sea.
Hydraulic action is the erosion that occurs when the motion of water against a rock surface produces mechanical weathering. Most generally, it is the ability of moving water (flowing or waves) to dislodge and transport rock particles.
Organic weathering happens when plants break up rocks with their growing roots or plant acids help dissolve rock. Once the rock has been weakened and broken up by weathering it is ready for erosion. Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind or gravity.
Continual erosion and deposition narrows the neck of the meander. Often during a flood the river will cut through the neck. The river continues on its straighter path and the meander is abandoned. New deposition seals off the ends and the cut-off becomes an oxbow lake that will eventually dry up.
When there is a very high discharge (usually during a flood), the river cuts across the neck, taking a new, straighter and shorter route. Deposition will occur to cut off the original meander, leaving a horseshoe-shaped oxbow lake.
An oxbow lake is a U-shaped lake or pool that forms when a wide meander of a river is cut off, creating a free-standing body of water. In South Texas, oxbows left by the Rio Grande are called resacas. In Australia, oxbow lakes are called billabongs.
An oxbow lake starts out as a curve, or meander, in a river. A lake forms as the river finds a different, shorter, course. The meander becomes an oxbow lake along the side of the river. Oxbow lakes usually form in flat, low-lying plains close to where the river empties into another body of water.
Such valleys can be up to 100 km (62 mi) long, 4 km (2.5 mi) wide, and 400 m (1,300 ft) deep (its depth may vary along its length). Tunnel valleys were formed by subglacial water erosion. They once served as subglacial drainage pathways carrying large volumes of melt water.
