1. Clines Cline means ‘rapid change in’ Thermocline is a rapid change in temperature Pycnocline is a rapid change in density

2. Three Layered Ocean –Surface Layer – 100-200 m thick Much of it is mixed by wind, waves and currents, so it’s known as the mixed layer. There often exists a seasonal thermocline, or region of rapid temperature change, in this layer –Intermediate Layer- from 200m to 1,500m Characterized by the permanent thermocline, the zone of transition between warm surface water and the cold water below. Do not confuse with seasonal thermocline. The permanent thermocline rarely breaks down and is a feature of the deep ocean, not of shelf regions. –Deep and Bottom Layers- below 1500m Technically these are two different kinds of water but they are both uniformly cold at about 4  C.