Geology of Earth Plate Tectonics

Layers of the Earth The Earth's interior is composed of three primary layers: Core Mantle Crust

The Core The Earth’s core is made of mainly iron and nickel These heavy elements were pulled by gravity to the center of the Earth 2 layers: Inner core is solid metal Outer core is liquid metal Extremely high temperature and pressure

Mantle: River of Rock Hot, soft rock. Like Silly Putty!! So hot it’s soft, but not liquid Hot rock rises up from the depths and cooler rock descends This creates very slow-moving, circular currents called CONVECTION CURRENTS

CONVECTION CURRENTS IN THE MANTLE!!!

What are these convection currents causing at the surface?

The Crust Outermost layer of the Earth. Where we live! Rocks, soil, and seabed. 5 miles thick beneath the oceans 25 miles thick beneath the continents.

The Rock Cycle: Igneous, Sedimentary and Metamorphic

Igneous Rocks Extremely common in the Earth's crust, igneous rocks are volcanic and form from cooled, hardened magma or lava.

Sedimentary Rocks “Sediments” are formed by erosion of larger rocks. They are laid down in layers over time. These small particles undergo compaction to form rock Fossils are most frequently found in sedimentary rock, which appears in layers, called strata.

Metamorphic Rocks Metamorphic rocks were sedimentary or igneous rocks that have been transformed by heat and pressure. The heat may come from nearby magma or hot, ion-rich water intruding into existing rock. It can also come from subduction, when tectonic forces draw rocks deep beneath the Earth's surface. High pressure causes rock deformation during mountain building when continental plates collide.

Metamorphic Rocks

The Rock Cycle

Plate Tectonics

Plates The plates make up Earth's outer shell Churning convection currents in the soft mantle below propel them along like a conveyor belt. The movement of the plates creates three types of tectonic boundaries.

Types of Boundaries Collide!! Depart from each other Plates move from a fraction of an inch to about 5 inches a year. A plate moving at 2 inches a year will travel about 30 miles in a million years. Convergent plates toward one another. Collide!! Divergent plates move apart. Depart from each other Transform plates move sideways in relation to each other. Sliding!!

Convergent Plates 3 Types of Convergent Plates: Continental-Continental Oceanic-Continental Oceanic-Oceanic

Convergent Plates: Continental--Continental Where continental plates collide, the crust crumples and buckles into mountain ranges (Himalayas)

Himalaya Mountain Range

Convergent Plates: Continental--Oceanic Ocean plate dives under the continental plate in a process called subduction. Overlying plate lifts up to form mountain ranges. The subducting plate melts creating active volcanoes. A deep trench runs right along the boundary

Convergent Plates: Oceanic--Oceanic Subduction Uplift (Islands form in a volcanic arc) Trench forms at boundary

Divergent Plates Divergent boundaries occur when plates move away from each other (Depart!) “Seafloor spreading” in the oceans creates new rock: Under water mountain ranges form as magma rises when a crack forms Rift Valleys are formed with oceanic ridges on either side. On land, giant troughs may form where plates are tugged apart.

A cloud of hydrothermal fluids streams from a black smoker, or mineral chimney, along the Mid-Ocean Ridge off the west coast of Mexico. Black smokers are common to spreading zones in plate boundaries

Transform Boundary Plates slide past each other. Pressure builds up and is released when the plates move. This causes a lot of shallow earthquakes! California’s San Andreas Fault

Transform Plates

Where will Los Angeles be in the future?

Not at plate boundaries: HOT SPOTS: Area of the earth where a plate moves over a magma chamber/hot spot Hawaii:

Yellowstone National Park

Review Layers of the Earth Types of Rock and the Rock Cycle Plate Tectonic Boundaries: Convergent Divergent Transform