Earth - History

Question 1

When did Earth form?

Answer 1

4.5 BYA

Question 2

Protoplanetary Disk

Answer 2

This is an accretion disk feeding a central star

Question 3

How did Earth emerge?

Answer 3

Dust and gas in protoplanetary creating planetismals by electrostatic and gravitiation influence, which gradually collied and accrete

Question 4

How did the moon form?

Answer 4

Earth collision with Theia, a mars-sized planet.

Question 5

What does Earth composition depend on?

Answer 5

Density differences and gravitational influences

Question 6

What was the early earth composed of?

Answer 6

The core like heavy elements like iron and nickel, whilst the crust/mantle composed of silicates, water and air, which are buoyant.

Question 7

How much of the Earths volume and mass is the core?

Answer 7

16% and 32% respectively.

Question 8

Bullen Discontinuity

Answer 8

This separates the liquidic outer core from the solid inner core

Question 9

What is the inner and outer core seperated by?

Answer 9

The Bullen discontinuity.

Question 10

How does Earth density change with depth?

Answer 10

Crust is 3cm^3, 5cm^3 and the core about 12cm^3

Question 11

How much of the Earths volume and mass is the mantle?

Answer 11

85% and 67%

Question 12

Function of the mantle

Answer 12

Convection currents drive tectonic activity, and forms the crust

Question 13

Peridotites

Answer 13

Ultrabasic or ultramafic intrusive rocks, being dense and coarse-grained texture, as layered igneous complex

Question 14

Fracture Zones

Answer 14

Valleys that cut across midocean ridges, providing passage for flow of cold bottom water between basins

Question 15

Xenoliths

Answer 15

Fragments of mantle brought to Earths surface during eruptions

Question 16

How does the crust form?

Answer 16

Partial melts from the mantle

Question 17

Seismic Waves

Answer 17

These are waves eminating from a source like explosision and shock waves, until reflected from a surface.

Question 18

P Waves

Answer 18

Waves where particle motion is parallel to wave motion

Question 19

S(Shear) Waves

Answer 19

Waves where particle motion is perpendicular to wave motion.

Question 20

Where does the lower mantle stretch from?

Answer 20

The seismic discontinuity to the core-mantle boundary (660km to 2900km)

Question 21

What is the lower mantle composed of?

Answer 21

SiO2, MgO, FeO and CaO

Question 22

Process of mantle convection?

Answer 22

Emerge from coolness from surface relative to interior, with thermal convection, cold material sinking being dense whilst hot is light and rises.

Question 23

Wilson Cycle

Answer 23

Models opening/closing of ocean basins, with tectonic subduction and divergence as supercontinents assemble and dissassemble.

Question 24

Process of Wilson cycle…

Answer 24

A stable craton with a hotspot rising beneat it, heating it and causing upward swelling, where it may split
Creates an ocean basin between them which can widen thousands of miles.
Subduction zone form in ocean basin
Collision of contients inevtiable

Question 25

Continental Crust

Answer 25

This is a granite, sedimentary and metamorphic rock layer forming contients and shallow seabeds

Question 26

Oceanic Crust

Answer 26

Resides under oceans formed at oceanic ridges at divergent plate boundaries.

Question 27

Composition of oceanic crust?

Answer 27

Basalt, troctolite and habbro(25% igneous and 75% sedimentary)

Question 28

Composition of continental crust?

Answer 28

Gabbro and granitoids(95% igneous and 5% sedimentary)

Question 29

When does isostasy emerge?

Answer 29

Density differneces in continental crust and mantle

Question 30

What is the crust mineral and ion concentration?

Answer 30

88.1% iron, and 11.9% in oxygen, silicon and aluminium.

Question 31

Why are silicate ions important?

Answer 31

Weathering of them forms soils and sands

Question 32

What is quartz composed of?

Answer 32

Silicon dioxide with a tetrahedral framing, minerlisatg which forms sands

Question 33

Dominant rock fo the upper mantle

Answer 33

Peridotite made up of olivine and pyroxene

Question 34

What catalyses magma generation?

Answer 34

H2O addition, increasing temperatures or decreasing pressure

Question 35

Bowen Reaction Series

Answer 35

Decsribes the crystalisation and cooling, forming distinct minerals based on type of mother insults

Question 36

What are the phases of bowen series?

Answer 36

Ultramafic
Mafic
Intermediate
Felsic

Question 37

Ultramafic

Answer 37

Ingeous rocks with less thant 45% silica and high Mg, Fe , Co and Ni.

Question 38

Mafic

Answer 38

Igneous rocks with 45-55% silica, dominant in Fe and Mg, typically black.

Question 39

Intermediate

Answer 39

55-65% silica and 5-20% quartz

Question 40

Felsic

Answer 40

More than 65% silica, like granite and rhyolite.