Hi,
1. It spreads over the ground.
Is the above sentence correct?
2. It spreads on the ground.
What is the difference between (1) and (2)? These sentences are OK, although you'd obviously need a context in which you'd say something like this. Sometimes, you could probably interchange them. Other times, maybe not.
eg The mist spread over the ground means that the mist was close to but slightly above the ground.
Best wishes, Clive