Earth: Inside and Outside Exam Review Geologistare scientists who study the forces that make and shape the earth. Constructive forcesand destructive forcesare the forces responsible for shaping the surface of the earth. Constructive forcesbuild new landforms (ex: mountains). Destructive forceswear away existing landforms (ex: erosion). 1
Earth is made up of 4 different layers. As you move inward, towards the center of Earth, temperature and pressure increase. The 4 layers of the Earth are the crust, mantle, outer core, and inner core. The crust is the thinnest layer. The crust is made up of oceanic crustand continental crust. Oceanic crust is more dense and made mostly of basalt. Continental crust is less dense and made mostly of granite. The mantleis made of molten rock called magma. Convection currentsin the magma cause the continental and oceanic plates to move. 2
The core of the Earth is divided into the inner core and outer core. The inner core is a solid, dense ball of iron and nickel. Although the inner core is the hottest, the intense pressure keeps the metal in solid form instead of liquid form. The outer core is a layer of molten metal. The convection currents in the outer core cause the inner core to spin creating Earth s magnetic field. Continental Drift The Earth s crust is broken into 7 plates. When all the plates were joined, it was called a super continent or Pangaea. Alfred Wegeneris the German scientist who developed the theory of Continental Drift. Evidence to support Wegener s theory include landforms, fossils, and climate. 3
The continents move due to seafloor spreading. Seafloor spreading adds new ocean floor when magma breaks through the ocean crust along the mid-ocean ridge. The old ocean floor is pushed back under the continents through a process called subduction. The old rock is melted and turns back into magma in the mantle. Seafloor Spreading 4
Seafloor Spreading and Subduction Plate tectonicscombined the ideas of seafloor spreading, continental drift, and the existence of the continental and oceanic plates. There are 3 types of plate boundaries: divergent, convergent, and transform. Divergent boundaries are places where the plates move apart or away from each other. These types of plates create rifts. 5
Convergent boundariesare places where plates move towards each other. These type of plates create mountainsand trenches and cause volcanic eruptions. Transform boundariesare places where plates slide past each other. These type of plates cause earthquakes. 6
Earth s Soil Soil is created from loose, weathered parts of Earth s crust. Soil is made of humus, water, weathered rocks/minerals, and air. Loamis a type of soil that is made up of equal parts of sand, silt, and clay. Parent rockdetermines the texture of the soil Basalt parent rock will create fine textured soil. Graniteparent rock will create coarse textured soil. Rocks and Minerals Minerals are naturally occurring, inorganic solids with a definite crystal structure and chemical composition. Minerals make rocks. Rocks are identified by color, texture, and mineral composition. There are 3 types of rocks: igneous, sedimentary, and metamorphic. 7
Igneous rocksform from cooling lava (outside the earth) or magma (inside the earth). Sedimentary rocksform from the remains of dead plants/animals and particles of other rocks being pressed together. Metamorphic rocksare created from already existing rocks that are exposed to heat, pressure, and/or chemical reactions that change them into something new. The Rock Cycle 8