What process is responsible for building successive fossil layers on earth

The process that is responsible for building successive fossils layers on earth is called DEPOSITION.
Deposition refers to the process by which sediments are added to a particular land form. There are different types of sediments and they are made up of different elements. A sediment can be in form of rocks and mineral debris, a precipitate formed from dissolution of a mineral in water or remains of other plants and animals. As these sediments are added to the foundational fossils layers, they form deposits which result in building up of successive layers.

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water