Journey to the Center of the Earth

Scientists that study the Earth Geologists: Scientists that study the forces that make and shape planet Earth. They study the chemical and physical characteristics of rock. Geologists study the processes that create Earth’s features and search for clues about Earth’s history. Geology is the study of the planet Earth.

Scientists that study the Earth Paleontologists: These scientists study the forms of life existing in former geologic periods. The science of Paleontology helps us learn about the history of different species that have inhabited Earth. Information we have regarding dinosaurs, wooly mammoths, trilobites, and other extinct species come from fossil formations found and studied by paleontologists.

Forces that Cause Surface Changes Constructive Forces: Shape the surface by building up mountains and landmasses. (Example Surtsey-2 Miles) Destructive Forces: Slowly wear away mountains and eventually every other feature on the surface. (Example: Weathering)

How do we know about the interior of the Earth? Any ideas???? (Hint it is not because we sent Brendan Frasier down there)

How do we know about the interior of the Earth? We know about the composition of the interior of the Earth because of Seismic Waves. (Earthquake Waves) The speed of these seismic waves and the paths they take reveal how the planet is put together. P (primary) waves can travel through every layer of the earth. In solids, these waves generally travel almost twice as fast as S waves and can travel through any type of material. S (secondary) waves can only travel through solids.

P and S Waves The arrival of the P and S waves differs as shown the seismograph reading to the right. The difference in arrival times of these two types of waves can help scientists locate the epicenter of earthquakes.

Layers of the Earth There are 4 main layers to the Earth. Crust, Mantle, Outer Core, and Inner Core. As you go towards the center of the Earth the temperature and pressure increases greatly.

The Crust The crust includes rocks, mountains, soil and water. The crust is the smallest layer of the earth. (Apple Example) There are two types of crust oceanic crust (Basalt which is an igneous rock) and continental crust (rocks like Granite which is an igneous rock)

The Mantle The mantle is a layer of hot rocks The mantle is solid but has liquid like characteristics. (It’s kind of like Silly Putty) The mantle is the largest of the layers of the earth It is mainly composed of silicon, oxygen, iron, and magnesium.

The Outer Core The outer core is a layer of molten metal that surrounds the inner core. In spite of enormous pressure the outer core behaves like a thick liquid. Currents in the liquid outer core force the solid inner core to spin at a slightly faster rate than the rest of the planet. These currents in the outer core create the Earth’s magnetic field. This is why you can use a compass and the Earth is protected from some of the harmful rays of the sun. Composed of mostly Iron and Nickel

The Inner Core The inner core is a dense ball of solid metal. It is also mainly composed of iron and nickel. Temperature range is probably between 2,000-5,000 degrees Celsius. The center of the inner core is thought to be as hot as the surface of the sun.

Temperature, Pressure, and Density Increasing On average for every 40km you dig deeper into the earth the temperature increases by 1 degree (Celsius). Mantle varies in temperature from 870-2000 degrees Celsius. Cores vary in temperature from 2,000-5,000 degrees Celsius. If it is 100 degrees Fahrenheit then it is 37 degrees Celsius.

Temperature, Pressure, and Density Increasing The deeper you go into the various layers of the earth the greater the pressure in the surrounding rock. Pressure is the force pushing on a surface or area. Because of the weight of the rock above, pressure inside Earth increases as you go deeper. The density which is the mass divided by volume also increases as you go further into the earth.

Plate Tectonics Plate Tectonics is the geological theory that states that pieces of Earth’s crust are in constant, slow motion, drive by convection currents in the Earth’s mantle. No plate can budge without affecting the other plates surrounding it. As the plates move, they collide, pull apart, or grind past each other. Discussion of Convection Currents. (on the board) Short Convection Current Video

Plate Boundaries Map

Plate Tectonics Plate movements cause volcanoes to erupt, mountain ranges to be formed, and earthquakes to occur. Plate Tectonics are responsible for the deformation of Pangaea. Plate Tectonics Introduction Plate Tectonics Evidence Movement of Earth's Tectonic Plates The Man Behind Plate Tectonics

Plate Movement The earth is divided up into 16 plates. Along these plate boundaries is where much of the geological interactions such as earthquakes, mountain formation, and volcanoes occur.

Evidence of Plate Tectonics Mountain ranges and sea floor basins line up between continents. Certain ancient fossils (Mesosaurus and Lystrosaurus) are found in places now separated by oceans. Coal deposits in arctic areas. Glacier scratches on rocks in deserts.

Transform Plate Boundaries Along transform boundaries, crust is not created nor is it destroyed. A transform boundary is where two plates slip past each other, moving in opposite directions. Earthquakes occur frequently along these boundaries. San Andreas Fault is an example of a transform plate boundary.

Divergent Plate Boundaries The place where two plates move apart or diverge, is called a divergent boundary. Most divergent boundaries occur at the mid-ocean ridge such as the one found in the Atlantic Ocean. The Atlantic Ocean is currently growing an average of 3cm a year. This is about the rate at which your fingernails grow. Volcanoes can occur at divergent plate boundaries because the weak crust can have magma from the mantle seep upwards.

Divergent Plate Boundaries Some divergent plate boundaries occur across continents. When divergent plate boundaries occur across continents they are called rifts. There is a giant rift across Africa called the Great Rift Valley which may someday split the eastern part of Africa away from the rest of the continent.

Convergent Plate Boundaries The place where two plates come together, or converge, is called a convergent boundary. When two plates collide the density of the plates determines which one comes out on top. Oceanic crust which is made of basalt is more dense than continental crust which is made mostly of granite. When 2 plates carrying continental crust collide, neither is dense enough to force the other plate on top of itself. This is how giant mountains are created as giant plates collide with neither of them going under or over the other plate. Volcanoes often times occur under plate boundaries when a process called subduction occurs. This occurs when an oceanic plate is more dense then the continental plate it is hitting into.

Trenches When an oceanic plate and a continental plate converge. The oceanic plate subducts under the continental plate. This action causes deep sea ocean trenches as well as volcanic activity

Trenches Mariana Trench is the deepest trench in the world. It is about 1580 miles long and 43 miles wide. It’s deepest point is about 7 miles down. This is why even though the Atlantic ocean is growing every year that same land is being recycled in the Pacific Ocean.

Tsunamis A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean. This is generally caused by earthquakes, volcanoes, or underwater explosions. Hollywood Tsunami Video

The Earth is Old!!!!!!!! The earth is approximately 4.6 billion years old. It is broken up into different Era’s and Period’s that are generally ended by mass extinction events. For example the Cretaceous Period ended 65 million years ago (mya). This period marked the end of the age of the dinosaurs.

Geological Time Scale

Some Important Geological Era’s and Period’s Pre-Cambrian is an era that covered from 4.6bya to 570mya. There is a very limited fossil record from this period of time. Most of the organisms found are stromatolites. Stromatolites were ancient archaebacteria that built up small rock masses. From 4.6bya to 2.5bya there was very little from oxygen in the atmosphere. The only organisms that existed were anaerobic organisms. Around 530mya an event called the “Cambrian Explosion” occurred where the fossil record shows a large amount of diversity in the fossil record with a great variety of organisms.

Some Important Geological Era’s and Period’s The Paleozoic Era covers from 570mya-225mya. It includes the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian Periods of Geological Time. During this Era some of the most abundant organisms were trilobites (arthropod-similar to crustaceans), echinoderms, sharks, early reptiles, and ferns.

Some Important Geological Era’s and Period’s The Mesozoic Era spanned from 225mya-65mya and included the Triassic, Jurassic, and Cretaceous Periods of time. These periods of time are well known for all species of dinosaurs, early birds (archaeopteryx), mammals, and flowering plants.

Some Important Geological Era’s and Period’s The Cenozoic Era which spans from 65mya ago to present time. It includes the Tertiary and Quaternary Periods. This period includes such organisms such as large carnivores, mammals (us), grass lands, mammoths, and saber toothed tigers.