Question

How fossilation takes place under the ground

Answer 1

for fossliation it takes thousand of years and a very high pressure for a fossil to form

Answer 2

from some billons of years back... some shells and some aquatic animals' remains forms a layer in the soil and forms as fossil of them..
after; dinosaurs and some fish fossils which were on earth a some millons years ago.. also forms fossils and this is the process by which fossilation takes place under the ground

I hope this information mag be helpful to u :)