Deltas

* Deposition: The primary force creating deltas is the deposition of sediment carried by rivers as they enter a larger body of water (like a lake or ocean). The water slows down, losing energy, and the sediment settles out.

* Water Flow: The flow patterns of rivers and currents within the larger body of water influence the shape and size of the delta.

Dunes

* Wind: Wind is the dominant force shaping dunes. It picks up sand grains, carries them, and deposits them in areas of lower wind velocity, creating characteristic dune shapes.

* Gravity: Gravity plays a role in the downwind movement of sand grains and the formation of dune slopes.

* Vegetation: Plants can stabilize dunes and influence their development, especially with their roots.

Canyons

* Erosion: The primary force behind canyon formation is erosion by water (rivers) or ice (glaciers).

* Weathering: Weathering (processes like freezing and thawing, chemical breakdown) breaks down rocks, making them more susceptible to erosion.

* Tectonics: Uplift of land masses (due to tectonic plate movement) can create a relative increase in elevation, making a river cut down more rapidly, creating canyons.

* Gravity: Gravity pulls water downhill, contributing to the erosive power of rivers and the deepening of canyons.

Summary

* Deltas: Primarily deposition of sediment by rivers.

* Dunes: Primarily wind erosion and deposition of sand.

* Canyons: Primarily erosion by water (rivers) or ice (glaciers), aided by weathering and tectonic uplift.