Structure of the Earth Chemical Composition Earth is divided into 3 layers: crust, mantle, core Based on compounds that make up each layer Less dense elements & compounds - crust & mantle More dense elements & compounds - core Separates by composition & density

The Crust 2 Types – Continental & Oceanic Less than 1% of Earth’s mass & volume Both share common elements such as: O, Si, Al Oceanic crust has 2x as much Fe, Ca, Mg The amount and combination of the elements in oceanic crust create minerals that are more dense than those in the continental crust.

Oceanic crust is thinner AND denser than continental crust Oceanic crust is thinner AND denser than continental crust. Continental ~2.7g/cm3 Oceanic ~ 2.9g/cm3 (made of granite) (made of basalt) The deepest hole ever drilled into the continental crust was in the Kola Peninsula in Russia in 1984. It was 12,226 meters deep! (Mt Everest is only 8,850 M high so the hole is 3,376 meters deeper than Mt Everest is high!) Because the temperature of the crust increases with depth, it is impossible to drill much deeper into the crust.

Element Types General distribution by volume (Earth)

Element Types Distribution within earth’s crust only

Do Now: Compare and contrast the 2 types of crust. What are their names? Compare their densities? What are they made of? (Top 4)

The Mantle Located between the crust and the core Most of Earth’s mass & volume is located in the mantle (67% & 83% respectively) Only physical observations of mantle are when mantle rock is uplifted to the surface (land or ocean floor)

The Core Extends from below the mantle to the center of the Earth Made of mostly Fe with some Si & Ni Approx. 33% of Earth’s mass & 16% volume

Physical Structure of Earth– 5 Layers Lithosphere means “rock” made up of 2 parts Crust Rigid upper part of the mantle Divided into pieces called tectonic plates Approx 0-100km Approx 1.57% volume The average depth is used to calculate the distance from the surface of the earth to the center which is approximately 6,380km. When constructing the model, label according to the book and ADD that the avg depth is 148km.

Tectonic plates – a block of lithosphere that consists of the crust and the rigid, uppermost part of the mantle. Lithosphere- Contains the crust, rigid upper part of the mantle & tectonic plates that seem to fit like a jigsaw puzzle pieces.

Asthenosphere means “weak” Solid rock that flows very slowly Upper part of mantle Plastic layer of the mantle -“malleable” soft – bendable Pieces of the lithosphere move on top of the asthenosphere Approx 100-700km Approx 9.42% volume

Mesosphere means “middle” Magma layer Strong, upper part of the mantle Between asthenosphere and core Approx 700-2,885km Approx – 34.30% volume

Mantle/Asthenosphere/Mesosphere Convection Convection currents from the mantle/mesosphere turn clockwise or counter clockwise This energy moves the asthenosphere As the asthenosphere moves, blocks of lithosphere also move, bring tectonic plates along for the ride

Charles Hapgood Crust Displacement Theory Theory states that lithosphere is not separate pieces that slowly move independently of each other and the rest of the Earth, but move as one piece. Supported by Einstein Supported by age of Antarctic ice Supported by discovery of flash frozen animals (wolley mammoth) https://www.bibliotecapleyades.net/ciencia/ciencia _earthchanges33.htm

Core – 2 parts Outer Core Inner Core Liquid iron layer of the core Approx 2,885-5,155km Approx – 35.64% volume Inner Core Solid iron layer of the core Approx 5,155-6,371km Approx 19.09% volume

Magnetic Field The combination of a liquid iron (mostly) outer core which is moving around a solid iron inner core produces Earth’s magnetic field. Differences in temperature, pressure and composition within the outer core cause convection currents in the molten metal as cool, dense matter sinks whilst warm, less dense matter rises. The Coriolis force, resulting from the Earth’s spin, also causes swirling whirlpools. This flow of liquid iron generates electric currents, which in turn produce magnetic fields. Charged metals passing through these fields go on to create electric currents of their own, and so the cycle continues. This self-sustaining loop is known as the geo-dynamo.

Earth’s chemical & physical composition Phys Layers Chem Layers Depth of Each Layer: Depth of Each Layer: Lith – 100km Crust – 0-100km Asth – 600km Mantle – 100-2900km Meso – 2185km Core – 2900-6370km Outer – 2270km Inner – 1216km = 6371km % Volume: Lith – 1.57% Asth – 9.42% Meso – 34.30% Outer – 35.64% Inner – 19.09% = 100.02%

The Earth’s Crust, Lithosphere, and Asthenosphere Mesosphere Crust Lithosphere Mantle Asthenosphere Mesosphere

2. What layers of physical structure make up the mantle? DO NOW: Discuss with a partner & record answers on your PPT Notes Sheet 1. What layer of physical structure contains all of the tectonic plates? 2. What layers of physical structure make up the mantle? 3. What layers of composition make up the lithosphere? 1 – Lithosphere 2 – Lithosphere, Asthenosphere, Mesosphere 3 – Crust & Mantle

Differences in Tectonic Plates Some plates have: an entire continent and oceanic crust only oceanic crust partial continental & oceanic crust

an entire continent and oceanic crust only oceanic crust Some plates have: an entire continent and oceanic crust only oceanic crust partial continental & oceanic crust Tectonic plates are not neatly divided along continental lines. North American plate includes the North American continent, Greenland, and half of Iceland.

Tectonic Plates float on top of the asthenosphere in a similar way that ice floats on the surface of water. Plates cover surface of asthenosphere, touch one another, and move around. Lithosphere displaces the asthenosphere Thick tectonic plates (made of cont. crust) displace more than thin plates (made of oceanic crust)

Mapping the Earth’s Interior Seismic waves – vibrations caused by earthquakes. travel at different speeds speed depends on density and composition of material faster through solids faster through denser rock slower through liquids

Seismographs - measure the times at which different seismic waves arrive and record the differences in their speeds Scientists use the measurements to calculate the density and thickness of each physical layer of the Earth.