How long will it most likely take for the processes in the rock cycle to change most of Granite Mountain into sediment?

The process of the rock cycle in changing most of granite mountain into sediment can take millions of years

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen