Presentation on theme: "Our Dynamic Earth. Our Earth is made up of rock, air, water and living organisms. Rock = Geosphere Air = Atmosphere Water = Hydrosphere Living."— Presentation transcript:
Our Dynamic Earth
Our Earth is made up of rock, air, water and living organisms. Rock = Geosphere Air = Atmosphere Water = Hydrosphere Living organisms = Biosphere
Earth is composed of rock – both solid and molten – as well as various metallic elements. This solid part of the Earth, as well as the soil and loose rock on the exterior, makes up the geosphere.
The Earth’s geosphere is divided into three chemical sections: The crust, composed almost entirely of light elements, like silicon. The mantle, which is 68% of the Earth’s mass. The core, the innermost layer; it is composed of very dense elements, such as nickel and iron.
The crust makes up less than 1% of the Earth’s mass. There are two types of crust: ◦ Continental crust, and oceanic crust.
Continental crust is about km thick. It is also made up of lightweight and low density materials.
Oceanic crust is much thinner – it’s only about 5 km thick! It is also made up of heavier and denser materials.
The mantle is about 2900 km thick. It is made up of dense materials, which are rich in iron. The mantle is semifluid; the molten rock flows very slowly, which lets the solid plates move on top. ◦ Much like cereal flows on top of syrup!
Outer CoreInner Core The outer core is composed of dense liquid metallic elements. Mainly nickel and iron. The inner core is composed of solid nickel and iron. This is due to the immense pressure found at the center of the Earth.
1. The Earth’s solid elements (soil, earth and rock) are collectively called the __________. 2. The geosphere has three chemical layers. List them. 3. ___________ crust is about 5 km thick, and is made of relatively dense materials. 4. Why is the inner core solid?
The Earth can also be divided into five layers, based on its physical properties. They are: ◦ Lithosphere – rigid and solid earth ◦ Asthenosphere – plastic; made of molten rock ◦ Mesosphere – Lower mantle, transitions to the liquid outer core ◦ Outer Core – made of dense, molten iron and nickel ◦ Inner Core – made of solid iron and nickel
The lithosphere is cool, solid and rigid. It is divided into many smaller pieces called tectonic plates.
The asthenosphere is semi-fluid, molten rock. This allows the tectonic plates to move on top. This motion is essential to our Earth‘s appearance.
As discussed earlier, our crust is divided into smaller tectonic plates. These plates glide on the surface of the upper mantle. The movement of these plates can have far-reaching effects on us.
A great deal of Earth’s tectonic activity takes place at the boundaries of the tectonic plates. ◦ Tectonic activity deals with activity that affects Earth’s surface. Enormous forces are at work whenever the tectonic plates collide, pull apart, or slip beside each other.
When the plates collide with each other, earth is pressed upward and folds. This leads to the creation of mountain ranges.
When plates slide past each other, faults – breaks in the Earth’s crust – sometimes appear. The intense forces involved when this happens cause earthquakes. Most earthquakes are so minor that we can’t feel them.
The magnitude of an earthquake is the energy that is released. We use the Richter scale or the more modern moment magnitude scale (MMS) to measure this energy. The lowest magnitude that can be detected is about 2.0. The greatest magnitude that has ever been recorded is 9.5. Earthquakes that cause widespread damage typically have a magnitude of 7.0 and up.
Earthquakes can cause damage in various ways: ◦ Pressure (P) and shear (S) waves cause vibrational motion. P-waves cause up-and-down motion, and S-waves cause side-to-side motion. S-waves are much more dangerous. ◦ Earthquakes can cause tsunamis, or large tidal waves, if the originate in ocean areas. ◦ Earthquakes can liquify sandy areas, causing buildings and other structures to sink into the ground.
1. What layer of the Earth contains the tectonic plates? (2 possible answers) 2. Why can Earth’s tectonic plates move? 3. Most tectonic activity occurs along Earth’s _____________________. 4. Mountain ranges are formed when tectonic plates _________________. 5. Is it possible to never notice an earthquake? 6. Describe one way than an earthquake can cause damage.
Volcanoes are, in essence, large vents for molten rock to rise to the surface. We call this molten rock magma while it is underground, and lava once it is above ground.
Volcanic vents often form when plates move apart from each other. This can happen on the surface or underwater. Some vents appear due to weak points in the crust, called hot spots.
Volcanic eruptions occur when magma is trapped underground, and the pressure builds up to critical levels. Some volcanoes do NOT erupt, as magma is not trapped, and can flow freely.
Volcanic eruptions can have devastating effects on the Earth’s surface. ◦ Ash, dust and rock can bury building, crops and organisms. ◦ Ash can mix with water to form dangerous mudflows. ◦ Ash and dust can disrupt engines and breathing. ◦ Ash and sulfurous gases can reach the upper atmosphere. Here, they block sunlight, which reduces the average global surface temperature.
Weathering is the process of breaking rock down into smaller pieces. Erosion is the process of moving the broken rock and loose dirt elsewhere. There are many forces that cause weathering and erosion: ◦ Wind ◦ Water and mudflows ◦ Plant life ◦ Human activity
1. Volcanoes are primarily ___________________. 2. What are hot spots? 3. Why do some volcanoes NOT erupt? 4. Describe one way that a volcano can cause damage. 5. List one means of weathering and erosion on Earth.