the hands moving
Most of the time, change, especially global change, happens gradually -- so gradually in fact that we barely notice that anything's different. Time passes, one day changes for another, but we don't usually notice the hands moving.

what does "so gradually in fact that we barely notice that anything's different. Time passes, one day changes for another, but we don't usually notice the hands moving" mean?

Question

the hands moving
Most of the time, change, especially global change, happens gradually -- so gradually in fact that we barely notice that anything's different. Time passes, one day changes for another, but we don't usually notice the hands moving.

what does "so gradually in fact that we barely notice that anything's different. Time passes, one day changes for another, but we don't usually notice the hands moving" mean?

Answer

"The hands moving" here refers to those of a clock. It means that on the time scale of a human life, geological change is so gradual that we don't notice it.