geo Flashcards
list the internal structure of the earth
the crust, the mantle, the outer core and the inner core
what is the crust
the crust is the thinnest part of the earth and it is also where we live. it consists of two types of crust which is continental and oceanic crust
what is the mantle
the mantle is about 1800 miles thick and it is made up of thick,rocky substances and amounts to about 85% of the total mass of earth and it is also the largest layer of earth
what is the outer core
the outer core is made up of lava. this lava is believed to be made up of iron and nickel and extends to a depth of 3000 miles beneath the earths surface
what is the inner core
the inner core extends 9000 miles towards the center of the earth. this is a solid ball made of irons and nickel.
who made the continental drift theory
german geographer alfred wegnener
convergent/ destructive plate boundaries
two crusts, oceanic and continental move towards each other. This forms deep sea trenches, volcanic activities and fold mountains
divergent/ constructive plate margin
two plates move away from each other in opposite directions. this forms mid-ocean ridges(the mid-atlantic ridge), shallow earthquakes
transform/ transcurrent
plates move horizontally or sideways in opposite directions but parallel to each other. this forms fault lines, rift valleys and violent earthquakes
what is weathering
weathering is the process whereby rocks are physically broken down or chemically modified by climatic or biological elements
the three types of weathering
physical, biological and chemical
physical weathering
the break down of rocks into smaller fragments
chemical weathering
decay of rocks caused by alternation of the mineral composition through chemical reactions with water and air
what is erosion
the process in which earthen materials are worn away and transported by natural forces such as wind or water
what are extrusive volcanic features
extrusive volcanic features are features that can be found on the earth’s surface
some extrusive volcanic features are
shield volcanoes
lava plateau
lava domes
cinder/ash cones
caldera
composite cones
explain the formation of composite cones
they fom when different types of eruptions deposit different materials around the sides of a volcano. altering eruptions of volcanic ash and lava causes layers to form.
explain the formation of shield volcano
shield volcanoes are usually constructed almost entirely of basaltic and/or andesitic lava flows which were very fluid.
explain the formation of lava plateau
these are landforms created by volcanic activity. When shield volcanoes erupt, magma flows from the earth’s mantle through fissures in the crust
explain the formation of lava domes
lava domes form from the slow extrusion of highly- viscous sillicic lava. These lavas are too thick to spread out into a lava flow.
explain the formation of caldera
this forms when magma chambers are partially emptied during large eruption and the land surface subsides
explain the formation of cinder/ash
form from ash and magma cinders partly burned, solid pieces of magma, that fall to the ground following a volcanic eruption.
what are intrusive volcanic features
this includes batholith, laccolith, sill and dyke
what is batholith
this is a very large feature formed when an underground reservoir of molten rock cools and hardens
what is laccolith
a mass of igneous rock that is intruded between sedimentary beds and produces a domical bulding of the overlaying strata
what is sill
a sill is formed when magma flows horizontally between rock layers, roughly parallel to the surface
what is dyke
this is a vertical sheet of rocks formed when magma moving towards the surface cools and hardens
