Introduction to Earth Science Unit 6 APES Lecture Introduction to Earth Science

Geologic Time Overview Precambrian Paleozoic Mesozoic Cenozoic

Questions How many extinctions have occurred/are occuring? Where did the oxygen come from about 2.7 bya? During what PERIOD was the majority of coal formed? What event proceeded the development of multi-celled organisms?

Earth Compositon Core: Intermost zone; Made up of Nickel and Iron. Inner Core solid; Outer Core Liquid Mantle--molten rock or magma--circulates by convection currents. Asthenosphere: Outer part of mantle—semi molten—ductile Lithosphere: Brittle, outermost layer. Includes the crust.

Theory of Plate Tectonics Plate Tectonics--Earth’s Lithosphere is divided into plates, most of which in constant motion-- This is called the tectonic cycle--build up and break down lithosphere... Oceanic plates--primarily oceans Continental plates--primarily land masses

Type of Plate Contact Divergent Plate Boundaries: Fig a-oceanic plates move apart.--sea floor spreading. Convergent Plate Boundaries. Plates move towards each other. Oceanic plates heavier metal--iron crust... In plate tectonics, a convergent boundary, also known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide. As a result of pressure, friction, and plate material melting in the mantle, earthquakes and volcanoes are common near convergent boundaries. When two plates move towards one another, they form either a subduction zone or a continental collision. The nature of a convergent boundary depends on the type of plates that are colliding. Where a dense oceanic plate collides with a less-dense continental plate, the oceanic plate is typically thrust underneath because of the greater buoyancy of the continental lithosphere, forming a subduction zone. At the surface, the topographic expression is commonly an oceanic trench on the ocean side and a mountain range on the continental side. An example of a continental-oceanic subduction zone is the area along the western coast of South America where the oceanic Nazca Plate is being subducted beneath the continental South American Plate.

Plate Contact 2 Collision of two continental plates--The Himalayan Mountain Range was formed by the collision between two continental plates... Transform faults-c--plates slide sideways.

Plate Tectonics 2 Movement driven by convection cells Seafloor spreading Subduction--the heavier oceanic plate slides underneath the lighter continental plate

San Andreas Fault

Consequences of Movement As volcanos move over geologic hot spots, can form volcanoes. Hawaiian Islands...

Questions What kind of plate boundary formed the Rocky Mountains? What type of boudary would be the San Andres Fault? What type of boundary is formed by the Himalyas? What is an oceanic trench?

The Himalayas

Convection and Earth Layers

Rock Cycle