The processes that have shapedPresentation Transcript
The Processes That Have Shaped Planet Earth Mr. Bradford
How Do We GetThe Earth’s Magnificent Features?
How The Earth Formed• The Earth formed from the same dust cloud that formed the sun.• As the dust circled around the sun it clumped and began to grow.
How The Earth Formed• Soon a proto-planet formed that swept up the remaining dust and particles in its path.
The Early Earth• The beginning of Earth was marked with volcanic action and bombardment from meteors.• Meteors added essential elements crucial for life.
The Early Earth• After a while the Earth cooled, an atmosphere formed and the crust solidified.• Volcanic (outgassing) activity contributed to the atmosphere.• Comets and Meteors contributed the the water on Earth.
What is the Earth Made Of ?Composition of Earths Atmosphere Composition of Earth Nitrogen 78.1% Iron 32.1% Oxygen 20.9% Oxygen 30.1% Argon 0.9% Silicon 15.1% Carbon dioxide, Methane, Magnesium 13.9% Rare (inert) gases 0.1% Sulfur 2.9% Nickel 1.8% Calcium 1.5% Aluminum 1.4% Other 1.2%
Earth’s Rocks• Igneous Rocks--formed when molten magma cools and are dividedinto two main categories: plutonic (intrusive) and volcanic (extrusive).Intrusive rocks result when magma cools and crystallizes slowly withinthe Earths crust (example granite), while volcanic or extrusive rocksresult from magma reaching the surface either as lava or fragmentalejecta (examples pumice and basalt) PumiceGranite
Earth’s Rocks• Sedimentary Rock--For thousands, even millions of years, littlepieces of our earth have been eroded--broken down and worn away bywind and water. These little bits of our earth are washed downstreamwhere they settle to the bottom of the rivers, lakes, and oceans. Layer afterlayer of eroded earth is deposited on top of each. These layers are presseddown more and more through time, until the bottom layers slowlyturn into rock.
Earth’s Rocks• Metamorphic Rock--formed by subjecting any rock type todifferent temperature and pressure conditions than those in which theoriginal rock was formed. These temperatures and pressures are alwayshigher than those at the Earths surface and must be sufficiently high so asto change the original minerals into other mineral types or else into otherforms of the same minerals.
The Layers of the Earth
The Layers of the Earth• The inner core is solid iron• The outer core is liquid iron• The mantle is composed of iron (Fe), magnesium (Mg), aluminum (Al), silicon (Si), and oxygen (O) silicate compounds.• The mantle is solid but is at a temperature of 1000o C, so it can deform slowly like hot plastic.• The crust is composed of calcium and sodium aluminum- silicate minerals.• The crust is thin, cool and brittle. It can break and crack easily.
Convection• Something that is hot is less dense than something that is cool.• More dense (cooler) things will tend to sink while less dense (hotter) things will tend to rise.
Convection in the Earth• The convection process happens in the Earth as well.• The cooler, denser crust will sink to the bottom, while the hotter, less dense inner regions will rise to the top.• When convection happens on the Earth it drives a process known as Plate Tectonics.
Plate Tectonics• The Earth’s crust is broken into different segments.• These different segments are called plates.• There are seven major plates.• These plates move (slowly) over the earth, crashing and grinding against each other.
Continental Drift• In the past all the continents were one large continent named Pangaea.• Plate tectonics contributed to the breakup of Pangaea into the continents we have today.• The continents continue to move about 5 to 10 cm per year.
Effects of Plate Tectonics• Earthquakes happen when two plates rub against each other.• Ridges form when two plates move apart from one another.• Volcanoes and trenches other mountains form when two plates collide.
Earthquakes• The boundary where two plates rub against each other is called a transform boundary.• Earthquakes occur along this boundary also called a fault.
Earthquakes• San Andreas Fault, California
Ocean Ridges• Ocean ridges form when two plates pull apart from on another.• This is known as a divergent boundary.• Hot magma will rise up at this boundary, solidify, and form underwater mountain ranges.
Volcanoes• A convergent boundary is where two plates collide.• When plated collide, one plate usually gets subducted, or pushed beneath the other plate. This is known as a subduction zone.• Volcanoes and earthquakes form near these subduction zones.
VolcanoesAs the subducted platesinks, it will grow hot,melt, and form magmawhich will rise underpressure and form anearthquake.When the pressuregrows strong enough itwill erupt
Diagram of a Volcano
Mt. St. Helens Before May 18, 1980
Mt. St. Helens After May 18, 1980
Effects of Volcanoes on Earth Volcanic soil is ideal for plant growth. Volcanoes added much needed water vapor to Earth’s atmosphere in the beginning. Large eruptions can cause a mass extinction of plant and animal species. This happens mainly from the ash that lingers in the atmosphere for long periods of time, blocking the sun. Some of the poisonous gas will rain down in the form of acid rain.
Hot Spot Volcanoes Hot Spot volcanoes are less violent than those near subduction zones. The crust slowly moves over a “hot spot”—an area of magma formation. The movement will create a string of volcanic islands that The Hawaiian islands were formed will cool and flourish with life. (and are still being formed) by a hot spot volcano.
The Pacific Ring of Fire
Mountains Mountains can form when two plates collide causing one or both plates to rise up. Other Mountains are formed when a plate under pressure will swell, fold and fault.
Mountains—Folding and Faulting
Folding and Faulting
Mt. Everest Mt. Everest is the highest mountain in the world. It is 29,028 ft. (5 ½ miles) high. Mt. Everest is part of the Himalayan mountain range which was formd when the the Indo-Australian plate collided with the Eurasian plate.
Mountains Other mountains are formed by the erosion of high plateau regions, leaving the harder parts standing above the surrounding area.
Glaciers A glacier forms when the annual snowfall exceeds the amount of snow and ice lost due to melting. Snow thus accumulates year after year. The snow at the bottom is compacted into ice (firn). Eventually the weight of the snow and ice becomes so large that the glacier begins to slowly fall (drift) downhill. The glacier carves a path in the landscape and leaves debris in behind.
Glaciers• Glaciers carve mountains and valleys• Much of the shapes we see in mountain ranges is a result of glaciers.
Glaciers—Cirques Cirques— steep bowl- like depression carved in the side of a mountain by a glacier’s snow field.
Glaciers—Horns Horn—a sharp, pointed peak carved by three or more opposing cirques cutting into the mountain.
Glaciers—Hanging Valleys Hanging Valley—the intersection of two valleys which were carved by glaciers. One of the valleys is larger and deeper than the other. The smaller valley “falls into” or “hangs” over top of the larger valley. Waterfalls often occur at these intersections.
Agents of Erosion Erosion is the breaking down of a material. Wind, Water and Chemicals are the main agents of erosion. These also help carve out our Earth.
Wind Erosion Wind will blow small debris (sand and other particles) that will carve out features in rocks, mountains and anything else in its path.
Water Erosion Rain and rivers, over time, carve away at rocks. Rivers will cut into the landscape and can form valleys and canyons over time. Oceans constantly shape the shores and eat into cliffs.
Wind and Water
Chemical Erosion Chemicals put into the atmosphere will come down in the form of acid rain and alter and destroy some landforms. Other chemicals will seep into the ground and waters change the composition of their contents.
Other Types of Erosion Water freezing in cracks and expanding Roots of plants growing into crevasses and growing to the point that the crack or crevasse widens and breaks. Human activity. Building, cutting down, blowing up, etc.