All the spheres on earth overlap with each other so that any changes occur in one sphere may affect the other.
EXPLANATION:
The four spheres of earth are Land (the lithosphere), water (hydrosphere), air (atmosphere), living things (biosphere). The living organisms receive sunlight, heat, and gases from the atmosphere and water from the hydrosphere.
All these spheres are interlinked with one other and assembles in a single location at the time of overlapping. Life would not be there on earth if all these spheres do not interact or overlap with each other.
Examples of the earth overlapping is given below;