The process that led to the creation of the continents. Earth crust is a clear bimodal in thickness. Ocean is usually about 4 mi (7 km) thick, varying mainly due to the temperature of the mantle below the ridges of sea-floor spreading, when was the crust. However, the thickness of a typical 22-25 mi (probability km) Continental Plate is ultimately controlled through agents of erosion, sedimentation and isostatic adjustments — by sea level. Oceanic crust is created at spreading Ridges, Continental Plate in Subdukcja zones. To the mantle, but the ocean is growing less, will be played about 30 times faster than the Continental Plate. in this connection, the continents, having regard to the average age of almost 2 billion years and the maximum age 4 billion years provide only directly accessible register covering most of the Earth's history. However, they are structurally more complex than the ocean swimming pools because of their Great antiquity and weak Rheology.