Tectonic plate (Noun) The pieces of the Earth’s crust that float on the mantle, causing continental drift and earthquakes and creating volcanoes, trenches, and mountains. “The Earth’s crust is divided into tectonic plates that move away, into, and around each other. Plate tectonics (Noun) The movement of the Earth’s tectonic plates. “Convergent, divergent, and transform boundaries are forms of plate tectonics.” Oceanic crust/plate (Noun) The part of the Earth’s crust found underneath oceans. “The larger the ocean, the larger the oceanic crust under it.” Continental crust/plate (Noun) A tectonic plate that carries a continent. “Convergent boundaries at continental plates create mountains.” Continent (Noun) A large piece of land. “The Earth is divided into seven main continents.” Continental drift (Noun) The movement of continental plates. “Continental drift is the reason why Pangaea once existed.” Crust (Noun) The outermost (first) layer of a planet. Usually composed of rock and is above the mantle. “The earth’s crust is measured to be 40 km.” Mantle (Noun) The layer of the Earth between the crust and core made of hot, semi-solid rock. “The Earth’s mantle is divided into the upper (under crust) and lower (above core) sections.” Core (Noun) The center of the Earth, composed of nickel and iron. The inner core is solid while the outer is liquid. “Scientists have yet to reach the core of the Earth.” Layer (Noun) The different parts of our planet: crust, upper and lower mantle, and outer and inner core. “The Earth has three main layers.” Divergent boundary (Noun) When two or more plates pull away from each other. “Rifts are created by divergent boundaries.” Diverge (Verb) When two or more tectonic plates move apart from each other. “When plates diverge, they can create a mid-oceanic ridge.” Mid-oceanic ridge (Noun) An underwater mountain range created by convection currents at divergent boundaries. “There is a large midoceanic ridge in the middle of the Atlantic Ocean.” Rift (Noun) A gap created by divergent boundaries. “A rift is made by two continental plates moving apart from each other.” Transform boundary (Noun) When two or more plates grind against each other, also called a strike-slip boundary. “Strong earthquakes are caused by transform boundaries.” Transform (Verb) When two or more tectonic plates grind against each other. “When tectonic plates transform, earthquakes and tsunamis can occur.” Grind (Verb) To rub against something. “Tectonic plates grind when they are at convergent and transform boundaries.” Earthquake (Noun) Wild and unexpected shaking of the ground caused by plate tectonics or volcanic eruptions. “Nepal experienced a strong earthquake recently.” Epicenter (Noun) The place on the crust above the exact point where an earthquake occurred. “The epicenter of an earthquake experiences the most damage.” Tremble (Verb) To shake. “The ground and buildings tremble during earthquakes.” Magnitude (Noun) The size or strength of an earthquake using the Richter scale as measured by a seismograph. “The recent Nepal earthquake had a magnitude of 7.8.” Tsunami (Noun) A large oceanic wave that moves quickly and is created by an underwater earthquake or plate tectonics. “Japan was hit by a large tsunami in 2011.” Convergent boundary (Noun) When two or more plates collide into each other. “Trenches are made by convergent boundaries.” Converge (Verb) When two or more tectonic plates move towards each other. “When plates converge mountains can be created.” Subduct (Verb) When a tectonic plate moves under another tectonic plate and create a subduction zone. “Tectonic plates subduct at convergent boundaries.” Subduction zone (Noun) A place between two plates at a convergent boundary where one plate is being pushed into the mantle. “Trenches can be found at subduction zones.” Trench (Noun) A long, narrow opening underneath the ocean. “Subduction zones create trenches.” Volcano (Noun) A mountain or hill formed by plate tectonics that has an opening that releases lava, rock fragments, hot vapor, ash, and gas. “When a volcano erupts, it affects the weather and the organisms living near it. Volcanic ash (Noun) Rock fragments, dust, and other materials released by a volcano during an eruption. “During an eruption, volcanic ash can affect the weather of an area.” Magma (Noun) Crust that has been melted into a liquid by the heat of the mantle. “Before lava leaves a volcano, it is called magma.” Lava (Noun) Hot, liquid rock released by volcanoes. “When a volcano erupts, it oozes lava.” Erupt (Verb) When a volcano releases lava, ash, gas, and other materials. “It is unsafe to be near a volcano when it erupts.” Explosion (Noun) The quick spread of energy from a source. “When a volcano erupts, it causes a big and loud explosion.” Fossil (Noun) Evidence of a past organism preserved and able to be studied. “Scientists study fossils to learn about how and where organisms lived before.” Geologic time scale (Noun) System used by scientists to organize events in the Earth’s history. “Each section of the geologic time scale lasts millions of years.” Eon (Noun) A period of time that lasts hundreds of millions to billions of years. “The Earth has only had four eons thus far.” Era/Period/Epoch (Noun) Units of geologic time that have a relative (estimated) length which depend on the geologic changes that occur in that time. “Their length of time from longest to shortest: era, period, and epoch. Stratigraphy (Noun) The study of rock layers and their fossils. “Scientists use stratigraphy to map fossils and events on the geologic time scale.” Stratum/Strata (Noun) A layer of rock. “Strata of rock are older the deeper you explore into the Earth. Radiometric dating (Noun) A method that uses radioactive isotopes to calculate the age of a fossil. “Scientists use radiometric dating to determine the exact time a fossil lived.”