Seamount
Topic: Oceans: Hydrological Cycle, Relief of the Ocean Floor, Temperature and Salinity · NCERT: Class 11, Ch 12 "Water (Oceans)"
Meaning
A seamount is an underwater mountain with a pointed top. It is volcanic, which means it was built by lava erupting on the sea floor. It rises about 3,000–4,500 m from the floor but does not reach the sea surface. Seamount chains often form as a plate moves over a hotspot, a fixed plume of hot rock under the plate. This makes them useful evidence of plate movement.
Example
The Emperor Seamount Chain runs north-west from Hawaii in the Pacific. It formed over about 80 million years as the Pacific Plate moved over the Hawaii hotspot. The Hawaii-Emperor bend shows where the plate changed direction.
Don't confuse with
- Guyot: a guyot is a flat-topped seamount. Waves wore its top flat, and then it sank. A seamount has a pointed top.
- Mid-oceanic ridge: a ridge is a long chain of mountains with a rift valley along its centre. A seamount is a single peak.