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Geology. The study of Earth. We d ivide g eology into two categories:. Physical Geology: To understand Earth’s long history. To understand the changes it has undergone.
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Geology The study of Earth
We divide geology into two categories: Physical Geology: To understand Earth’s long history. To understand the changes it has undergone Historical Geology: To establish a timeline of the vast number of physical and biological changes that have occurred in the past and may occur in the future
The Formation of Our Galaxy • It is believed that our solar system formed 4.56 billion years ago. That is 4,560,000,000 years ago. It all started with the remnants of a defunct or dead star.
Formation (continued) • The star exploded and there was a tremendous amount of dust and small particles floating around. Called a solar nebula • The particles and dust began to spin. The heavier particles stayed closer to the center than the gaseous particles.
Particles Collide • As the particles rotated around a center area, they banged into each other. • These central particles formed billions of small “planetesimals”. These were about 1 km in diameter. • Gravity began to pull the heavier particles toward the middle The Sun Ignited!!!!
What Happened Then? • When the sun ignited, it began a process called fusion. This is where hydrogen gets pushed together and form a new material helium. It also releases a tremendous amount of energy. • The energy pushed the gas particles far away, while the heavier planetesimals were not as affected.
Over Millions of Years • The solid planetesimals collided to make bigger bodies (Earth and Venus) • The gaseous area collided together to form some of the larger outer planets.
What about Earth? • Earth was a mix of radioactive elements, iron, nickel and assorted others. It was getting bombarded by other smaller particles and was expanding quickly. - The heat from the collisions and the radioactive decay caused some melting in the interior of the Earth
The Layers of Earth • This heat allowed some of the materials to melt and the denser ones would move to the center. • The less dense materials would “float” to the top. • This sinking and floating is still occurring today. • The center of our Earth is very hot with much molten iron and nickel.
Atmosphere and Oceans • Trapped gaseous materials are allowed to escape the core today and they still do through volcanic eruptions. • These eruptions that have occurred, much more frequently earlier, have pushed out enough gaseous materials to form our atmosphere. • Because we have an atmosphere that condenses, we have water, and oceans.
Homework Complete questions 1-7 on page 5 Also complete the key concepts and vocabulary for the first 3 sections of Chapter 1.