Active Earth Flashcards
most information comes from class or national geographic
what are the layers of the earth
inner core, outer core, mantle (and asthenosphere) and the crust.
explain the rock cycle
igneous rocks are formed by cooled magma / lava.
metamorphic rocks are formed by heat and pressure applied to any type of rock.
sedimentary rocks are formed by compaction and cementation of sediment.
rocks can be destroyed by melting, weathering or erosion.
how are rocks broken down in the rock cycle: physically
rocks are broken down physically by the agents of erosion such as wind water or ice as well as weathering.
how are rocks broken down in the rock cycle: chemically
Chemical weathering changes the molecular structure of rocks and soil. For instance, carbon dioxide from the air or soil sometimes combines with water in a process called carbonation. This produces a weak acid, called carbonic acid, that can dissolve rock.
(national geographic)
weathering
the breaking down or dissolving of rocks and minerals on the surface of Earth.
(national geographic)
erosion
the geological process in which earthen materials are worn away and transported by natural forces such as wind or water
(national geographic)
sedimentation
the deposition of rock fragments, soil, organic matter, or dissolved material that has been eroded
(national geographic)
how are igneous rocks formed
from cooling molten rock
extrusive igneous rock
extrusive igneous rocks are formed by the cooling of lava
extrusive rocks cool faster and therefore have smaller crystals
intrusive igneous rock
intrusive igneous rock is formed by the cooling of magma
intrusive rocks have bigger crystals due to longer cooling times
clastic sedimentary rock
rocks primarily made from smaller broken up rocks
chemical sedimentary rock
formed by chemical precipitation dissolving minerals in the rock
organic sedimentary rock
made from organic matter which contains carbon - hydrogen bonds
how do sedimentary rocks tell as about different time periods
the sediment traps organic matter which can be used to date the matter around it. the sediment on the bottom is older than the sediment on the top.
how are metamorphic rocks formed
when other rocks go under intense heat and pressure
regional metamorphism
process that occurs over broad areas in the lithosphere, leading to the formation of metamorphic rocks with a flaky texture
(national geographic)
contact metamorphism
a type of metamorphism where rock minerals and texture are changed, mainly by heat, due to contact with magma
(national geographic)
continental drift
when tectonic plates move the continents
fossil evidence
show how plants and animals as well as landscapes have evolved
sea floor spreading
when two oceanic plates drift apart and the magma from the mantle below forms to make a new crust.
magnetic striping
volcanic rocks, such as basalt, record the polarity of the Earth’s magnetic field. In other words, they contain crystals that point to magnetic north. When the basalt cools down from a molten state, those crystals are frozen in place and are all stuck pointing in the same direction. It’s like the rock has its own compass inside!
This means that rocks formed at different times have their magnetic crystals pointing in opposite directions. They can be used to determine the polarity of the magnetic field at the time they were formed!
The stripes are symmetrical on either side of the mid-ocean ridge.
The stripes are younger close to the ridge and older further away These features can only be explained by the theory of seafloor spreading!
(education perfect)
sediment thickness
differences in the thickness of the crust around the world.
converging plate boundries
this is were a subduction zone is formed one plate (often oceanic) has begun to sink under a bigger plate (often continental) as they were moving together. this causes lots of earth quakes and volcanoes.
diverging plate boundaries
when two plates are moving away from each other eg. sea floor spreading.
transform plate boundaries
when two plates move past each other in the opposite direction. causes earthquakes.
