Term 1 (from Stile) Flashcards
(33 cards)
Define ‘cementation’
The gluing together of sediment by new mineral crystals. Cementation can cause sediment grains to stick together, forming sedimentary rock.
Define ‘compaction’
The squeezing of sediment by the weight of overlying layers. Compaction can cause sediment grains to stick together, forming sedimentary rock.
Define ‘continental crust’
Crust that lies beneath a continent. Continental crust is about 25-70 km thick and is less dence than oceanic crust.
Define ‘continental drift’
The movement of continents around the surface of Earth. Continental drift thoery was proposed by Alfred Wegner in 1912 but was widely accepted only in the 1960s.
Define ‘convergent boundary’
A place where two tectonic plates move towards each other. At convergent boundaries, mountain ranges, ocean trenches, and volcanoes can form.
Define ‘crust’
The outermost layer of Earth. The crust is made of solid rock and is 5-70 km think. It is thickest underneath the continents.
Define ‘divergent boundary’
A place where two tectnoice plates move away from each other. At divergent boundaries, rift valleys and mid-ocean ridges can form.
Define ‘erosion’
The wearing away and removal of rock. Eroded sediment is transported by wind, water, or ice.
Define ‘fossil’
The remains of traces of an ancient organism preserved in rock. Fossils provide information about how life evolved and how Earth’s surface has changed.
Define ‘igneous rock’
Any rock formed by the cooling of magma or lava. The size of the crystals in an igneous rock indicates the speed at which it cooled. The faster it cooled, the less crystals, and vice versa.
Define ‘inner core’
The innermost layer of Earth. The inner core is a solid mixture of iron and nickel at extreme pressures and temperatures.
Define ‘lava’
Hot liquid located above the Earth’s surface. When magma rises up from the underground and flows on the surface, it is called lava.
Define ‘lithosphere’
The rigid outer part of Earth, made of the crust and upper mantle. The lithosphere is divided into slow-moving tectonic plates.
Define ‘magma’
Hot liquid rock located below the Earth’s surface. Magma can rise to the surface to form volcanoes.
Define ‘mantle’
The thickest layer of Earth, between the core and the crust. The mantle is made of solid and partially melted rock. It can flow over very long timescales.
Define ‘melting’
A change of state from solid to liquid. When rock is heated deep underground, it melts to form magma.
Define ‘metamorphic rock’
Any rock that has been changed bu intense heat and pressure. Heat and pressure can change the types of minerals and the size and shape of the crystals.
Define ‘mid-ocean ridge’
An underwater mountain system where new oceanis crust forms. Mid-ocen ridges form at divergent boundaries. New oceanic crust formed from cooling lava.
Define ‘ocean trench’
A deep valley in the ocean floor formed at a convergent boundary. Ocean trenches from where one plat subducts beneath another.
Define ‘oceanice crust’
Crust that lies beneath an ocean. Oceanic crust is about 5-10 km thick and is made up of basalt, a dense volcanic rock.
Define ‘outer core’
The later of Earth that lies between the mantle and inner core. The outer core is a liquid mixture of iron and nickel. Its flow generates Earth’s magnetic field. This process is known as geodynamo.
Define ‘plate boundary’
A border between two neighbouring tectonic plates. Tectonic plates interact at plate boundaries. This can cause earthquakes and volcanic eruptions.
Define ‘relative dating’
A method to determine if one rock layer is older or younger than another layer. In a sequence of sedimentary tocks, the lowest layer has the oldest relative age.
Define ‘rift valley’
A long depression formed when a continent is pulled apart. Rift valleys form at divergent boundaries in continental crust.
