What four processes were at work on protoplanet earth, and what did each do?

A protoplanet is a large planetary embryo that originated within a protoplanetary disc and has undergone internal melting to produce a differentiated interior. Protoplanets are thought to form out of kilometer-sized planetesimals that gravitationally perturb each other's orbits ... Such embryos weresimilar to Ceres and Pluto with masses of about 10^ 22