Our planet is shaped by a variety of cyclic changes that happen over and over (sometimes with different results) and unidirectional changes that involve changes that are unlikely to repeat. which events represent examples of unidirectional change?

Some examples of unidirectional change could be the progressive evolution of the solid Earth from a homogeneous compilation of planetesimals to a stratified planet, the forming of the oceans, the change in atmospheric composition, and the evolution of life.