Plate motion rates are measured in mm and cm per year.
Geologic events take time.
Lots of time. Given the great age of the Earth and the extraordinary long time intervals geologic processes take, it is clear that we must develop a notion of geologic time very different from our usual perception of time. It establishes the geologic time scale, one of geology's greatest products, that allows geologists worldwide to place local rocks into a global sequence. Lets look at what each of these can provide us. Stratigraphers use the layering in sedimentary rocks to infer the sequence of geologic events by applying two basic principles.