The Mid-Atlantic ridge is also
classified as a slow-spreading ridge, which are
typically very broad and have a deep
central rift valley.
Some rifts within the Mid-Atlantic Ridge are up to 6 miles (10 kilometres) wide and 2 miles (3 kilometres) deep. It also consists of numerous seamounts ( undersea mountains formed by volcanic activity): approximately 85 million of them, with over 2.5 million of them greater than 600 feet (200 metres) in height. The average height is around 180 feet (60 metres).