They sink to the bottom.
gravity
Gravity
erosion
Sediments carried by gravity are typically coarse-grained and unsorted. These sediments include boulders, cobbles, pebbles, and sand that are transported downhill by mass wasting processes such as landslides, rockfalls, and debris flows.
Water, wind, gravity, and ice can all move sediments from one place to another.
gravity
Air ,ice ,gravity ,and water
The second image shows sediments in motion. The movement is likely caused by the flow of water or the force of gravity on the slope where the sediments are located.
The action of water and gravity cause them to form in layers.
Gravity causes mass movement with sediments. Examples of this are anything with slope. Since gravity pulls everything to the center of the Earth, and natural slopes exist, gravity pulls rocks down different varieties of slopes. An example of this can be a mud slide. This can cause sediments to be pulled downward and deposited in erosion.
Sediments in sedimentary rock can be transported by wind, water, or glaciers
When gravity and friction overcome the ability of the moving water to move them.