Detailed Instructions: Given a list of steps and an additional step, determine where the step fits into the original list of steps. A correct answer, correctly places the given step into the set of steps so that it creates a new plausible set of steps. Output must be formatted as 'After step n', where n is the step number after which the given additional step is to be inserted.
Q: Steps: (1) When water freezes it becomes 10% bigger, or takes up 10% more space (2) The force of the pressure exerted on the rock surrounding it is enough to wedge the walls of the crack farther apart, thus expanding and deepening the crack (3) Clay expends when wet like ice does (4) This causes rock to break apart (5) Some plants like mosses and lichens are capable of growing without soil on bare rock (6) When they do this their roots penetrate pores and crevices and cause rocks to split apart as the roots force their way down through the rocks  
Where does the following step fit into the given list of steps: As water expands it puts great pressure on the walls of anything containing it, including any rocks which happen to be surrounding it 
A:
 After step 1. 