1 Earths Layers The Earths rocky outer crust

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

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 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.

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.

USGS Graphics 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!!

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

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

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

13 - Divergent Boundary – Arabian and African Plates Arabian Plate Red Sea African Plate

14 Divergent Boundary – Iceland

15 -Convergent Boundary – Indian and Eurasian Plates Eurasian Plate Indian Plate

16 - Transform Boundary – San Andreas Fault

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

18 - Earthquakes 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.

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

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

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

Review • Name the 3 main layers of the Earth • What is a tectonic plate? • Name 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 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 boundary is this?

What type of plate boundary is this?