I've got a sinking feeling...
The river that has carried me along has now reached the sea - I think I'm being dumped.
Particles of rock cannot be transported forever. Rivers reach the sea, the wind stops blowing and glaciers melt - they dump the load of particles they were carrying. This process is called deposition.
During deposition particles of rock are laid down in layers. Heavier particles are normally dumped first and then covered by finer material. Layers of sediment build up over time. These layers form a sedimentary sequence.