Chapter 8 The Earth

How do we know that planet Earth really revolves and rotates? What is Aberration and what does it prove about the Earth? What is a Foucault Pendulum and what does it prove about the Earth? What is centrifugal force, what does it say we should observe about the Earth and what does this prove What is the Coriolis Effect, what does it prove about the Earth and give an example with a description of what is happening?

What is the structure of the interior of the Earth 8.2 How do we determine the age of the Earth? What are the three basic types of rocks and how are they formed? Give a basic description of the oceans and the continents

What is the structure of the interior of the Earth 8.3 What have we done to look at the interior of the Earth? What is the density and pressure like in the Earth’s interior and what are the consequences of the high pressure? What is heat flow, what causes it and what is the proof of this flow?

What is the structure of the interior of the Earth The Earth’s Magnetic Field – page 161 – in 1600 William Gilbert proposed the earth acted like a huge magnet that aligned the small magnets in compasses – Materials lose their magnetic properties when heated to 800K – Must be generated by a dynamo, must have materials the conduct electricity – Proof comes from changes in the earths magnetic field, the evidence is trapped in lava flows

What is the structure of the interior of the Earth Seismology – page 162 Question : What is the device that records earthquakes, what does it record, and how is this helpful to scientist? Internal Structure – page 163 – Seismic study have led us to a model of the earths interior: Crust, Mantle, and Core – At the crust and mantle seismic waves move faster, Lithosphere is below the crust but ridged, and below that is the Aesthenosphere which is partially melted – The core is broken into two areas, A liquid zone and a solid zone – mainly iron and nickel because of the high density

What is the structure of the interior of the Earth Plate Tectonics – page 164 Question: How long ago was plate tectonics accepted ? When was the first evidence noticed? Who first suggested the theory, and what was his ideas?

What Causes earthquakes, mountain ranges and volcanoes Seafloor Spreading – page 165 – The evidence of Wegener's ideas did not come until the 1960, when there where magnetic and mapping efforts conducted over the ocean floor – Harry Hess proposed that evidence suggested that the ridges where areas that allowed magma from the mantle to ooze up and solidify to form new ocean crust. – The magnetic flipping and rock age was the evidence that proved him right

What Causes earthquakes, mountain ranges and volcanoes Plate Motion – page 166 Questions : What are the three types of plate Boundaries? What is the function of each? Rate of Crustal Motion - Page 168 – The magnetic record indicates a motion of about 2 to 3 centimeters per year, this has been conformed by radio telescopes in Europe and North America – It has taken 200 million years for the Atlantic to form, no evidence found of other satellites in the solar system

Where did the Earth’s oceans and atmosphere come from and how they have changed with time Atmosphere – page 168 – The layer of gas that provides the air we breath, protection from ultraviolet radiation, protection from the cold of space……a unique system in our solar system – The composition is currently 78% nitrogen, 21% oxygen 1% argon and traces of everything else…..this has not always been the case. – Thermal Structure – draw figure 8.23 page 169 – The greenhouse effect is important for our survival, it cools us in the day and warms us at night by reflecting and trapping heat from the sun

Where did the Earth’s oceans and atmosphere come from and how they have changed with time Human Changes – page 170 Questions : Are there natural changes going on and how are they different from man made? Carbon Dioxide: What are the principle greenhouse gases, how to they get into the atmosphere, are they any drawbacks to the evidence? Aerosols : Why are they a problem, what is the effect, Is there a benefit Ozone : What is the threat, what is the damage, why would I care?

Where did the Earth’s oceans and atmosphere come from and how they have changed with time Magnetosphere – This is part of the earths atmosphere that is mainly magnetic fields – The Van Allen belts is a region of charged particles that surround the earth, look at figure 8.27 page 173 – The solar winds hit the magnetosphere at 1.6 million miles per hour, this distorts the field into a tear drop around the earth – Friction between the solar wind and the magnetic field in the tail cause charged particles to hit the atmosphere and form the Aurorae

Where did the Earth’s oceans and atmosphere come from and how they have changed with time Evolution of the Earth – Earliest evolution was the formation of the planets in the solar system through accumulation – When the material first came together the density was uniform…over time the fraction and compression pulled more dense materials to the center. – The earth is cooling from the inside out, the core rotates slightly faster, the core is getting larger, it has a density 13 times that of water

Where did the Earth’s oceans and atmosphere come from and how they have changed with time – Water was released from the rocks as the rocks were liquefied and released their materials – Water was released as water vapor from volcanic eruptions into the atmosphere, then fell as rain, there was enough water on the surface by about 3.5 billion years ago – Water is always being recycled, both through the atmosphere and through convection

Where did the Earth’s oceans and atmosphere come from and how they have changed with time – The primitive atmosphere was lost to space in time or from impacts – The secondary atmosphere came from volcanic outgassing….hydrogen, water vapor, carbon dioxide and nitrogen – Most hydrogen was lost to space, water vapor fell as rain and formed the oceans, the carbon dioxide dissolved into the oceans which made carbonate acid that formed limestone – The early atmosphere was therefore mainly Nitrogen, with some carbon dioxide and water vapor – Oxygen began forming about 2 billion years from photosynthesis, as the levels increased sunlight would break the O2 down and allowed ozone to form and allowing life to form