What is the 4th dimension? i have heard that it's time, it's a from of saying characteristic. i don't know i need on this, it's bother me for the pass week.

If you want to tell a friend about a fish you caught or a tree you cut down,
you're going to tell him WHERE you were ... its position in space, 3 numbers,
'x', 'y', and 'z' ... and also WHEN you were ... its position in time, one more
number. 

Dimensions are numbers used to describe the location of a point, and the
difference in location between two points.  With four numbers, you can exactly
describe the location of anything, and its distance from any other thing, in
space and time.

Sorting by the rock cycle

Liquid. good luck : )