July 8, 2016July 8, 2016July 8, 2016AF Carpinelli1 The Earth’s Interior

July 8, 2016July 8, 2016July 8, 2016Source: AF Carpinelli2 The Earth’s Interior –How Earth’s interior took on the characteristics it has… –How we know about the interior of the Earth… –The layers of the Earth as defined by composition

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli3 The Differentiated Earth… Earth shows differentiation Earth shows differentiation –Separation into layers due (in this case) to differing densities –Just like separation shown here

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli4 How Did Earth Become Differentiated? Earth became differentiated very early in its history (around 4.5 billion years ago) during the Great Bombardment Earth became differentiated very early in its history (around 4.5 billion years ago) during the Great Bombardment As material from space hit the young Earth, the heat from the impact melted the Earth leading to a magma ocean As material from space hit the young Earth, the heat from the impact melted the Earth leading to a magma ocean

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli5 The Iron Catastrophe The Iron Catastrophe is the name given to this event The Iron Catastrophe is the name given to this event –Heavy elements (iron, nickel) sink to the center of the Earth –Lighter elements (silicon, oxygen) rise to the surface

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli6 Demo – How Earth Became Differentiated Describe the demonstration you just saw and heard. Describe the demonstration you just saw and heard. –What position were the marbles in originally? –What brought about the change? –Where did the marbles end up? Why?

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli7 So, What’s the Big Deal? This early layering led to the way our planet functions today AND to the way life developed! This early layering led to the way our planet functions today AND to the way life developed!

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli8 How Do We Know About Earth’s Interior

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli9 How Do We Know About Earth’s Interior Three ways, actually! Three ways, actually! –First, volcanic data brings some of the interior up to us. –Second, density information…  Since the overall density of the Earth is 5.5 g/cm 3 and the density of the surface is 2.2 g/cm 3, the interior must be denser! –Third, seismic (earthquake) waves act like an “ultrasound” and give a picture of the interior

How Do We Know About Earth’s Interior Most of our knowledge of Earth’s interior comes from the study of P and S earthquake waves Most of our knowledge of Earth’s interior comes from the study of P and S earthquake waves –Travel times of P and S waves through Earth vary depending on the properties of the materials –S waves travel only through solids July 8, 2016July 8, 2016July 8, 2016AF Carpinelli10

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli11 Earth’s Layers Earth’s layers are defined two ways Earth’s layers are defined two ways –Layers defined by Composition are the core, mantle, and the crust (oceanic and continental) –Layers defined by Physical Properties (behavior) are the inner core, the outer core, lower mantle, asthenosphere, and lithosphere

Layers defined by Composition July 8, 2016July 8, 2016July 8, 2016AF Carpinelli12

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli13 Layers Due to Composition Core Core –Innermost layer of the Earth –Composed of nickel and iron  Metallic, not rocky like the other layers –Very dense – more than 6x the density of the surface –Makes up one-third of Earth’s mass and is 3480 km thick (of 6400 km total)

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli14 Layers Due to Composition Mantle Mantle –Middle layer of the Earth –Rocky, rather than metallic like the core –Composed of mafic minerals (silicates high in magnesium and iron (Fe)  High quantities of peridotite –Makes up 48% of the thickness and 67% of Earth’s mass

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli15 Layers Due to Composition The Crust The Crust –Outermost layer of the Earth –Rocky, mostly silicates –Two types  Oceanic (most of the crust) – made of mafic rocks – mostly basalt  Continental – made of felsic rocks – mostly granite

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli16 Layers Due to Composition –Oceanic crust is very thin – only about 7 km on average – and is very young (180 million years on average)  Denser than continental rock by about 0.3 g/cm 3 –Continental crust is thicker – up to 75 km thick – and up to 4 billion years old  Question – since oceanic crust is denser, what happens when oceanic and continental crust interact?

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Layers of the Earth based on Composition (Chemical) vs. Physical Properties (Behavioral/Mechanical) July 8, 2016July 8, 2016July 8, 2016AF Carpinelli19

Sea Floor Spreading with Bill Nye July 8, 2016July 8, 2016July 8, 2016AF Carpinelli20

July 8, 2016July 8, 2016July 8, 2016AF Carpinelli21 Summarize… What does differentiation mean? What does differentiation mean? Why did Earth become differentiated? Why did Earth become differentiated? In what two ways are Earth’s differentiated layers defined? In what two ways are Earth’s differentiated layers defined? Identify one property each of the core, mantle, and crust. Identify one property each of the core, mantle, and crust.