The Geosphere Chapter 3

Geosphere The solid part of the Earth that consists of all rock, and the soils and sediments on Earth’s surface. Located mostly in Earth’s interior. Average distance through the center of the Earth to the other side: 12,756 km

Geosphere The deepest that has been drilled is 12 km into the Earth. Scientists use seismic waves to learn about Earth’s interior. Same waves that travel through the Earth’s center during earthquakes. Altered by the nature of the materials which they travel through. Seismologists must measure the change in speed and direction of waves.

Geosphere Seismologists have learned that Earth is made up of different layers from seismic waves.

Composition of Earth Earth’s divided into 3 layers: The Crust The Mantle The Core Theses layers are made up of progressively denser material as you get nearer to the core.

Composition of Earth Crust – the thin outer layer of Earth made of light elements. Makes up less than 1% of Earth’s mass. Thinnest layer of Earth. 5 to 8 km thick beneath oceans 20 to 70 km thick beneath continents

Composition of Earth Mantle – layer beneath the Earth’s Crust. Makes up 64% of Earth’s mass. Approx. 2,900 km thick. Made of medium density rocks.

Composition of Earth Core – innermost layer of the Earth. Composed of the densest elements. Radius of approx. 3,400 km. Divided into inner and outer core.

Structure of the Earth The Earth is divided into five layers based on the physical properties of each layer. The Lithosphere The Asthenosphere The Mesosphere Outer Core Inner Core

Lithosphere 15-300 km thick. Cool, rigid, outermost layer. Consists of Crust and upper mantle. Divided into Tectonic Plates. Plates move around on top of Asthenosphere. Continental and Oceanic Crust.

Asthenosphere 250 km thick. Solid, plastic layer. Between mesosphere and lithosphere. Consists of mantle rock that flows very slowly. Allows tectonic plates to move on top of it.

Mesosphere 2,550 km thick. “middle sphere” The lower layer of the mantle between the asthenosphere and the outer core.

The Outer Core 2,200 km thick. Outer shell of Earth’s core. Consists of liquid nickel and iron.

The Inner Core 1,228 km radius. Sphere of solid nickel and iron at the center of the Earth. 4,000 – 5,000 degrees Celsius. Solid because of enormous pressure of the Earth.

Plate Techtonics Pieces of the rigid, outermost layer of the Earth (lithosphere). Glide across the asthenosphere much like ice drifts across a pond. Continents are located on tectonic plates and move around with them.

Plate Tectonics

Plate Boundaries Much of the geologic activity at the surface of the Earth takes place here. Plates separate, collide, or slip past one another. This can cause mountains to form, earthquakes, or volcano eruptions.

Mountains Where plates collide, the crust becomes thicker and eventually forms mountain ranges. Himalayas: began to form 50 million years ago. Plate containing Asia and plate containing India collided.

Earthquakes Fault: a break in the Earth’s crust along which blocks of the crust slide relative to one another. Breaks send vibrations to the ground which are known as earthquakes. Earthquakes are occurring at all times but most are too weak to feel. http://videos.howstuffworks.com/howstuffworks/236-how-earthquakes-work-video.htm

Richter scale Used by scientists to quantify the amount of energy released during an Earthquake. Magnitude: energy released. Smallest felt: 2.0 Largest felt: 9.5 Each increase of a whole number indicates 31.7 times more energy than the number before it. http://videos.howstuffworks.com/howstuffworks/236-how-earthquakes-work-video.htm

Richter Scale

Earthquake Occurance Earthquakes occur on or near plate boundaries. San Andreas Fault – runs almost the entire length of California. North America plate meets Pacific plate.

Earthquake Hazard Earthquakes cannot be predicted. Can only predict where they are most likely to occur. Determined by past and present seismic activity. South Carolina – 1886, 6.6 - 7.3, unpredicted, sand flowed like a liquid and caused lots of damage.

Volcanoes A mountain built from magma – melted rock – that rises from the Earth’s interior to the surface. Mostly at faults where plates are colliding or seperating. Can occur on land or under ocean. Majority surround the Pacific Ocean. http://videos.howstuffworks.com/discovery/29456-assignment-discovery-eruption-of-mt-vesuvius-video.htm

Volcanoes

Local Effects of Volcanoes Devastating to local economies. Cause great human loss. Clouds of hot ash, dust, and gases. Burn up everything in their path. Volcanic ash and water mix = mudflow. Breathing difficulties.

Pompeii

Pompeii The city of Pompeii is a partially buried Roman town-city near modern Naples in the Italian region of Campania, in the territory of the commune of Pompeii. Along with Herculaneum, its sister city, Pompeii was destroyed and completely buried during a long catastrophic eruption of the volcano Mount Vesuvius spanning two days in 79 AD. The eruption buried Pompeii under 4 to 6 meters of ash and pumice, and it was lost for over 1,500 years before its accidental rediscovery in 1599. 

Pompeii http://videos.howstuffworks.com/discovery/28991-assignment-discovery-pompeiis-destruction-video.htm http://videos.howstuffworks.com/discovery/7164-images-from-pompeii-video.htm http://videos.howstuffworks.com/discovery/29456-assignment-discovery-eruption-of-mt-vesuvius-video.htm

Pyroclastics Pyroclastic material is another name for a cloud of ash, lava fragments carried through the air, and vapor. Very hot.

Global Effects Can change Earth’s climate for several years. Clouds of volcanic ash and sulfur-rich gases may reach the upper atmosphere. Reduce amount of sunlight reaching Earth’s surface. Drop in temperature.

Erosion Removal or transport of surface material is called erosion. Caused by wind and running water. Moves rock and changes its appearance. The older a mountain range, the longer the forces of erosion have acted on it.

Water Erosion Both rivers and oceans can reduce dramatic changes on Earth’s Surface. Waves from ocean storms can erode coastlines. Over time, rivers can carve deep gorges into landscape.

Wind Erosion Wind can blow soil away very quickly in places where there aren’t a lot of plants. Beaches and deserts. Soft rocks erode more easily than hard rocks.