chapter 2

Earth has a stratified atmosphere. What does that mean? What are the two dominant elements comprising the atmosphere? Does the composition of the atmosphere change with elevation?

Earth has atm that is stratified Layers Nitrogen > Oxygen Stratified Atm doesn't change much Constant composition

What is element is the core dominantly made of? Is the core solid or liquid or both?

BOTH inner is solid outer is liquid

Solar wind, what is it, and what protects us from it?

Amount of matter greatly increases approaching the sun. The sun ejects after outward into space as the solar wind. Solar wind Magnetic and electric charged particles Steam in all directions Consist of protons Electrons Only a small percentage of solar wind hits earth Dipole Magnetic field serves as protection

Earth's dimensions: No need to memorize the numbers, but you should know which layers are big (volume-wise) and which are small.

Crust smallest Mantle - largest Core middle

What causes air pressure? Where is it highest? Lowest?

Decreasing with increasing alt Higher alt lower pressure Caused by the weight of overlying material

What is the Brittle-Ductile transition?

Defined by a significant change in rock physical props (viscosity) Also by as the depths below which earthquakes don't occur

Density of earth...what does density tell us about rocks on the surface? Near the core? Is density uniform?

Earth's mass and vol given a whole earth density of 5.5 Typical rocks at surface have density 2-3 g/cm^3 Near core If density increased towards center then a significant of mass would be at outer edges Then centrifugal (not centripetal) force would cause the planet to become a disk Not true If center was liquid earth would rise and fall like the tides Earthquakes provides energy trans as seismic waves Velocity of waves change with density

What does felsic, mafic, and ultramafic mean? Know at least one rock name for each of these.

Felsic- more silica(less fe/mg) Less dense Granite Mafic = less silica(more fe/mg) More dense Gabbro Basalt Ultramafic - rare of surface (peridotite) Most common in earth because it's in mantle Range felsic/ intermediate(balance of mafic and felsic)/ mafic/

What generates the magnetic field on Earth?

Geodynamo - flow in the liquid iron outer core

What causes the Aurorae?

Ions escape Van Allen belt Van Allen belts two belts in inner mag field where high energy cosmic rays are trapped escaped ions are pulled to poles and create light in upper atm Borealis is northern australis southern

Does lithosphere = crust? Does asthenosphere = mantle?

Lithosphere Consist of crust and... No because there is a part of the mantle the upper cooler part that is lithospheric Does not convect, strong Asthenosphere Part of mantle that is hot enough for rock to become soft and flow Not liquid, weak Boundary between two LAB Lithosphere asthenosphere boundary

Earth has a dipole magnetic field. Know its features and what it protects us from.

Magnetic field grows stronger as separating distance decreases particles deflected by earth's field distort shape of earth's magnetic field in space van allen belts two belts in inner mag field where high energy cosmic rays are trapped Protections from solar rad Particles caught put on north southern lights

The Mantle: What is the composition? What is the general rock type? What is the density relative to the crust?

Mantle Upper trans Lower Solid rock later 2885 km thick 82% of earth's vol Ultramafic peridotite Below 100~150 km rock is hot enough to flow Convection hot mantle rises cold sinks

What is convection and where does this happen on Earth?

Method of heat transfer Dense things sink Cold is more dense Heat is less so rises Causes circular convection makes convection cells Causes pressure gradients which create wind Atm and inside of earth undergo convection

What is the Moho?

Moho is lower boundary of crust Marked by change in velocity of seismic P waves Change in composition 1909 by andrija mohorovic

Are there dominant elevations on Earth? Why?

Most land is 0-2km above sea level Most of the seafloor is 3-5km below sea level Because of topography?

Is Earth's composition uniform? What is the dominant element that comprises the bulk Earth? What are the two dominant elements in the crust?

Water and land Not flat has topography Below and above sea level Mostly iron > and oxygen > silicon > mag = other Crust O2 and silicon

The Crust: How many basic types? What are the compositions? What are the general rock types for each? Which is more/less dense? Which is thicker/thinner?

crust Ocean 3.0 density 7-10 km Mafic avg rock basalt/gabbro More dense floats lower Continental 2.7 density 35-40km Felsic avg rock granite Less dense floats higher Varying thickness

*Know the layers of Earth: crust-mantle-core, lithosphere-asthenosphere. Which are solid? Which are liquid? What layers are based on composition? What layers are based on how they react to stress (how the deform)?

crust Ocean 3.0 density 7-10 km Mafic avg rock basalt/gabbro More dense floats lower Continental 2.7 density 35-40km Felsic avg rock granite Less dense floats higher Varying thickness Mantle Upper trans Lower Solid rock later 2885 km thick 82% of earth's vol Ultramafic peridotite Below 100~150 km rock is hot enough to flow Convection hot mantle rises cold sinks Core inner - solid iron nickel Radius 1220 13 dense outer - liquid iron nickel sulfur 2255 thick Density 10-12 Lithosphere Brittle portion of earth interior Non flowing, rigid Material that moves plates Crust and upper mantle Asthenosphere Ductile portion of earth's interior Shallower under oceanic lithosphere Deeper under continental lithosphere Flows as a soft ductile solid <2 percent melt