Wind or water erosion can cause the sand to move from one place to another. The wind carries it by picking it up (just like the same affect with pollen) and it drifts to somewhere new. Water smashes against the shoreline and breaks it apart. It can then carry it outward with the waves or back into the ocean.
All in all: WATER OR WIND EROSION
The wind causes movement
Sand dunes in every desert are in almost constant movement. They are simply hills of sand and the wind changes them easily and often.
in what direction do sand dunes move
Sand dunes are cause by the movement of sand by the wind or water.
Sand dunes move inland through a process called wind erosion. As wind blows across the surface, it picks up loose grains of sand and carries them inland. Over time, the movement of sand grains creates a gradual shift in the position of the dune. This process can be influenced by factors such as wind speed, direction, and the presence of vegetation.
As you move sheets over sand, especially in a geological context, the friction and pressure can lead to the compaction and cementation of sand particles, resulting in the formation of sedimentary rocks like sandstone. This process can also create structures such as ripples or dunes on the surface. Additionally, the movement can lead to the formation of layers that record environmental changes over time.
Wind and water can move sand, with wind causing the grains to be transported in a process called saltation, and water moving sand through processes like erosion and sediment transport.
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Sand movement is erosion because it deals with the transportation of already weathered materials. However it is worth noting that the movement of sand can also cause weathering as the moving sand particles can act as an abrasive causing mechanical weathering.
The sea mounts help us understand the movement of tetonic plates because when the tetonic plates move's the earth's crust making little formations of sand underwater.
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Longshore currents shift sand and move water parallel to the shoreline