2 How it all started: Pangaea Pangaea was fully assembled by the Early Permian Period, some 270 million years ago. It began to break apart about 200 million years ago, during the Early Jurassic PeriodPangaea was a “supercontinent” consisting of all the current continents, except they were all together in one single large landform and slowly began to break apart
3 Slow Changes:Formation of Mountain Ranges: mountains can form many different ways:Earth’s tectonic plates crash together and because of the huge energies involved, the plates crumble and form mountainsMountains may form along fault lines-blocks of Earth are uplifted and tilted as two plates grind togetherMagma from beneath the Earth’s surface is pushed upward, but does not crack through, leaving behind a dome shaped mountain made up of hard rock
4 Slow Changes(cont.) Formation of Ocean Basins/Rift Valleys: They were formed from the break-up of Pangaea and drifting continentsA Tectonic plate carrying a continent splits apart, heat from magma comes up from deep within the earth, weakening/stretching the crust of the plate.Crust fractures on the sides allowing sections of the plate to drop, resulting in a basin/valley
5 Rapid Changes Volcanoes/Eruptions 2 types of Eruptions -Explosive: These eruptions happen when the magma is so thick that gas can not escape easily, the pressure rises and the gas eventually makes the magma explode-Flowing:These eruptions are less dangerous, since the magma in this case is less dense/ thinner the gas can escape and the magma does not explode, just runs outHow is a volcanic eruption caused?Magma, also referred to as lava, comes from deep within the earths surface and slowly rises to the volcano.Magma continues to fill the volcano and eventually will fill up and result in an eruptionWatch this video ->
6 Rapid Changes (cont.)Earthquakes -Caused by the movement of plates under earths surface -Occur along Fault lines -Shifting plates create energy called seismic waves - Shifting plates can slide against each other, pull apart or even push together As seen in the background picture, earthquakes cause devastating damage, areas closest to fault lines are effected the most since seismic waves are strongest close to the fault line.
7 The Surface is always changing… Earth is constantly changing, not only from the tectonic plates, but also the wearing and building up of earth’s surface.It can change in multiple ways includingWeatheringDeposition(part of erosion)Erosion
8 WeatheringWeathering- causes the disintegration of rock near the surface of the earth2 types of weathering-Mechanical-any of the various weathering processes that cause physical disintegration of exposed rock without any change in the chemical composition of the rock: Collision between rock surfaces can cause mechanical weathering.Chemical-any of the various weathering processes that cause exposed rock to undergo chemical decomposition, changing the chemical and mineralogical composition of the rock: Oxygen and acids are agents in chemical weathering.Watch this to help explain even better-The picture you see in the background is Mt.Rushmore. This is a perfect example of weathering, the rocks surrounding the faces are cracked and constantly being worn down by natural forces
9 Erosion/Formation of Rocks Erosion is the process in which weathered particles are picked up and moved from one place to anotherThe part of the erosion process in which sediment is placed in a new location is called depositionNatural forces such as wind, water and ice cause erosion by wearing down the earths surface
10 Types of Rocks 1.Igneous Rocks- are crystalline solids which form directly from the cooling of magma (heat is released as the magma sits and hardens)2.Sedimentary Rocks-These rocks are formed by the build up of dirt particles and sediment, they are compacted slowly over time as more layers of sediment deposit3.Metamorphic Rocks-Rocks in which the minerals which make up the rock become unstable and out of equilibrium with the new environmental conditionsAny rock can become a metamorphic rock with the right conditions
11 FossilsA fossil is remains of an organism which lived long ago which has been preserved in rock/soilFossils are the skeleton or bones of the organism imprinted into the rockFossils prove that organisms have evolved over time because animals/organisms today are similar to the fossils, but with changes or adaptations
12 Proof the Earth has evolved over time? The earths continents “fit together like a jigsaw puzzle”EarthquakesNatural surroundings and changes, mountains rising, basins forming, The Grand Canyon, etc.Fossils of animals have been found of animals which lived on land in South America and the SAME species in Africa, which means they had to be relatively close to another at one pointClimate ChangeFossils of extinct plants and animals, also fossils that are similar to todays mammals, plants, organisms etc.
13 Questions Kayla’s Questions- Can you explain why earthquakes occur? Contrast Pangaea and what the current world looks like in terms of continents.Lea’s Questions-1.Compare and Contrast Mechanical and Chemical Weathering2. If you were moving to a different part of the world, then would you want to be living near or farther away from a fault line? Why?