1 - Earth’s Layers The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick pieces (Plates) that drift on top of the soft, underlying mantle.

2 - The Crust Outermost layer 5 – 100 km thick Made of Oxygen, Silicon, Aluminum

3 - The Mantle Layer of Earth between the crust and the core Contains most of the Earth’s mass Has more magnesium and less aluminum and silicon than the crust Is denser than the crust

4 - The Core Below the mantle and to the center of the Earth Believed to be mostly Iron, smaller amounts of Nickel, almost no Oxygen, Silicon, Aluminum, or Magnesium

Convection is like a boiling pot. Heated soup rises to the surface, spreads and begins to cool, and then sinks back to the bottom of the pot where it is reheated and rises again. 5 - Plate Tectonics The Earth’s crust is broken into pieces also called Plates. The plates (pieces) are moving. The plates’ movement is driven by cooling of Earth (convection). Modified from USGS Graphics ? ? ?

6 - Plate Tectonics Greek – “tektonikos” of a builder Pieces of the lithosphere that move around Each plate has a name Fit together like jigsaw puzzles Float on top of mantle similar to ice cubes in a bowl of water

7 - What are the two types of tectonic plates? 1)Lithosphere 2) Asthenosphere

8 - What is the Lithosphere? Lithospheric plate The 100-km-thick surface of the Earth; Contains crust and part of the upper mantle; It is rigid and brittle; Fractures to produce earthquakes.

9 - What is the asthenosphere? Asthenosphere: Is the hotter upper mantle below the lithospheric plate; Can flow like silly putty; and It is an elastic solid, NOT liquid!! USGS Graphics

10 - Different Types of Boundaries 1) Transform (2) Divergent (3) Convergent

11 - Three Basic Types of Plate Boundaries Divergent Convergent Transform USGS Graphics Using hands to show relative motion

12 - Three Basic Types of Plate Boundaries Divergent Convergent Transform USGS Graphics

13 - Divergent Boundary – Arabian and African Plates

14 Divergent Boundary – Iceland

15 -Convergent Boundary – Indian and Eurasian Plates

16 - Transform Boundary – San Andreas Fault

There are a dozen large lithospheric plates (smaller plates not shown). Some plates have continents; some don’t. All are in motion Tectonic Plates

There are thousands of small earthquakes every day. “Strong” earthquakes ( about magnitude of 7) occur once a month. Magnitude of over 8 occur about once/year Earthquakes

Notice that the earthquakes coincide with plate boundaries, and the deepest quakes (blue) are in subduction zones. Modified from USGS Graphics 19 - Earthquakes & Plate Boundaries

Modified from USGS Graphics Volcanoes also tend to occur along the plate boundaries Volcanoes & Plate Boundaries

Plates move 1-10 centimeters per year (about the rate of fingernail growth) How fast are the plates moving?

Review Name the 3 main layers of the Earth What is a tectonic plate? Name the three different types of plate boundaries and one location on Earth for each one

Review Name the 3 main layers of the Earth – Crust, mantle, core What is a tectonic plate? – Pieces of the lithosphere that move around Name the three different types of plate boundaries and one location on Earth for each one – Divergent, Convergent & transform

What type of boundary is this?

What type of plate boundary is this?