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A Journey to the Center of the Earth The Science of Geology •  Geologists: scien.sts who study the forces that make and shape Earth, and search for clues about Earth’s history • “Geo” = earth
“ology” = the study of • Forces that change Earth’s surface are either • Construc2ve: shape surfice by building mountains and landmasses • Desctruc2ve: wear away mountains and surface features • There are currently 7 con.nents make up of layers of rock, and surrounded by oceans. Finding Evidence •  Geologists study Earth’s interior by indirect observa.on (we can’t get down there!) • They use seismic waves made by earthquakes to find out about the structure of Earth • From this geologists know the Earth is made up of dis.nct layers Our Journey to the Center • Condi.ons change as you move from the outermost layer, to the innermost layer • Temperature: • First 20 meters (60 feet) are cool • APer that, the temperature rises 1 C for every 30 meters (120 feet) • Pressure: (the force pushing on an area) • Pressure increases as depth increases Composi2on of the Earth •  Divided into three layers based on the compounds that make up each layer: 1.  the crust, 2.  the mantle, and 3.  the core 1.  The Crust •  The Crust • outermost layer of Earth made up of mountains, soil and water • 5 to 100 km thick • Thinnest layer of the Earth. • Two Types: • Con2nental – thicker, less dense; made of mostly granite • Oceanic – thinner, denser, made up of basalt rock 2. The Mantle •  The Mantle • Between the crust and the core. • Much thicker than the crust • Has two layers within the first 200km: • Lithosphere • Asthenosphere • The rest of the mantle is solid 3. The Core •  The Core • Central part of the Earth • Made up of two parts: • Inner Core • Outer Core • Makes up about 1/3 of Earth s mass, but only 15% of its volume (so it’s VERY dense!). •  It’s made mostly of iron (Fe) and a liale nickel (Ni) Earth’s Physical Structure ‐ Breaking it Down Further The Earth is divided into five physical layers, each with their own set of physical proper.es: 1.  The lithosphere 2.  The asthenosphere 3.  The mesosphere 4.  The outer core 5.  The inner core #1 ‐ The Lithosphere •  The outermost, rigid layer of the Earth. •  Made of two parts: • the crust • the rigid upper part of the mantle. •  Divided into about 20 pieces that are called tectonic plates. #2 ‐ The Asthenosphere •  A plas.c (flexible) layer of the mantle on which the tectonic plates move. •  Made of solid rock that flows very slowly, heated by convec.on currents in the mantle #3 ‐ The Mesosphere •  The strong, lower part of the mantle between the asthenosphere and the outer core. •  The prefix meso‐ means middle. (It’s called this because it is the middle of the five layers.) #4 & #5 ‐ The Outer & Inner Core The Earth s core is divided into two parts: •  Outer Core: mostly molten metal that behaves like a thick liquid •  Inner Core: the solid, dense ball of metal. The pressure squeezes iron atoms together, making them solid • about 6,380 km beneath the surface. Earth’s Magne2c Field •  Currents in the outer core force the solid inner core to spin • The inner core spins slightly faster than the Earth rotates • This spinning of the metal core creates Earth’s magne.c field • This is why compasses work and point toward North