Isostasy(2) The principle of isostasy governs the rise or subsidence of the crust until mass is buoyantly balanced Because of isostasy, all parts of the lithosphere are in a floating equilibrium a Low-density wood blocks float high and have deep“ roots;” whereas high- densit blocks foat low and have shallow“ roots
Isostasy (2) ◼ The principle of isostasy governs the rise or subsidence of the crust until mass is buoyantly balanced. ◼ Because of isostasy, all parts of the lithosphere are in a floating equilibrium. ◼ Low-density wood blocks float high and have deep “roots,” whereas high-density blocks float low and have shallow “roots
Earth's Surface: Land versus water The ocean covers 71 percent of Earth's surface Land occupies only 29 percent. Sea level fluctuates over time When climate is colder and water is stored as ice Sea level falls The shoreline moves seaward When climate gets warmers a The ice melts Sea level rises a The shoreline advances inland
Earth’s Surface: Land Versus Water ◼ The ocean covers 71 percent of Earth’s surface. ◼ Land occupies only 29 percent. ◼ Sea level fluctuates over time. ◼ When climate is colder and water is stored as ice: ◼ Sea level falls. ◼ The shoreline moves seaward. ◼ When climate gets warmer: ◼ The ice melts. ◼ Sea level rises. ◼ The shoreline advances inland
CEAN ARC OCEAN South pole 8- Equator Equa Land hemisphere Water hemisphere 46. 4% Land 11.6% Land 53. 6% Water 88. 4% Water
Earth's Surface: Land Versus Water (2) a Undersea mid-ocean ridges form a continuous feature more than 60.000 km long. a Mid-ocean ridges mark where two oceanic blates spread apart a New lithosphere forms in the gap a Passive margins have few earthquakes and little volcanic activity
Earth’s Surface: Land Versus Water (2) ◼ Undersea mid-ocean ridges form a continuous feature more than 60,000 km long. ◼ Mid-ocean ridges mark where two oceanic plates spread apart. ◼ New lithosphere forms in the gap. ◼ Passive margins have few earthquakes and little volcanic activity
180°150°120°90°60°30°0°30°60°90°120°150°180° 80° 60° 60° 40° 20 Equator 20 40° 40 g he overflowing Ocean
The overflowing Ocean