Figure 1. Mid-Atlantic Ridge emerges as the South American and African plates pull apart at the "slow" rate of approximately 30 millimeters per year. The axis of the ridge is marked by a 2 km deep rift valley, which is typical of most slow-spreading ridges. The map reveals a 12 km jog of the rift valley, a second-order discontinuity, and also shows a first-order discontinuity called the Cox transform fault. Colors indicated depths of from 1900 (pink) to 4200 meters (dark blue).