Abrasion (geology)

In addition to chemical and physical weathering of hydraulic action, freeze-thaw cycles, and more, there is a suite of processes which have long been considered to contribute significantly to bedrock channel erosion include plucking, abrasion (due to both bedload and suspended load), solution, and cavitation.

Bedload transport consists of mostly larger clasts, which cannot be picked up by the velocity of the streamflow, rolling, sliding, and/or saltating (bouncing) downstream along the bed.

Suspended load typically refers to smaller particles, such as silt, clay, and finer grain sands uplifted by processes of sediment transport.

Grains of various sizes and composition are transported differently in terms of the threshold flow velocities required to dislodge and deposit them, as is modeled in the Hjulström curve.

[citation needed] Coastal abrasion occurs as breaking ocean waves containing a sand and larger fragments erode the shoreline or headland.

[7] Seawalls are sometimes built-in defense, but in many locations, conventional coastal engineering solutions such as sea walls are increasingly challenged and their maintenance may become unsustainable due to changes in climate conditions, sea-level rise, land subsidence, and sediment supply.

[citation needed] Glacial abrasion is the surface wear achieved by individual clasts, or rocks of various sizes, contained within ice or by subglacial sediment as the glacier slides over bedrock.

While plucking has generally been thought of as a greater force of geomorphological change, there is evidence that in softer rocks with wide joint spacing that abrasion can be just as efficient.