Module 5 - The Rock Cycle Flashcards
What is extrusion?
The emission of magma onto the Earths surface where it forms a lava flow
What is weathering?
The in situ breakdown of rocks
What is erosion?
The removal of weathered material, usually by the physical action of transported fragments
What is transport?
The means by which weathered material is moved from one place to another
What are the methods of transport?
Water, wind, ice or gravity
What is deposition?
The laying down of sediment that occurs when a transporting agent loses energy
What is Burial?
It occurs when sediment is covered by younger layers of sediment accumulating on top of it
What is Diagenesis?
It defines all the processes that take place in sediments at a low temperature and pressure at or near the Earths surface
What is Recrystalisation?
The solid state process the changes minerals into new crystalline metamorphic minerals
What is metamorphism?
The changing of rocks in the Earths crust by heat and or pressure and or volatile content. It is isochemical and occurs in the solid state
What is partial melting?
The incomplete melting of rock in the lower crust or upper Mantle
What is magma accumulation?
Magma collecting within a magma chamber
When does crystallisation occur?
During the cooling of magma or lava so that solid mineral crystals form
What is an intrusion?
An igneous rock formed below the earths surface. The magma can be forced into pre-existing rocks such as along bedding planes and joints or by cutting across the existing rock
What is uplift?
The return of buried rocks to the Earths surface by tectonic forces
How long has the rocks cycle been going for?
Rocks seem permanent and unchanging but the truth is that they have been changing slowly all the time. The earth was formed 4500 Ma and some rocks have been around the cycle multiple times
What are the two processes that occur at the Earths surface?
Igneous and sedimentary
What are the igneous processes?
Magma within the Earths crust and upper Mantle can be erupted onto the surface as lava flows. If the eruption is more explosive, solid fragments called pyroclasts are produced. This process forms extrusive igneous rocks. The lava and solid fragments begin to cool at the surface and the lava becomes rock when crystals form from the magma and it becomes solid (crystalisation)
What are sedimentary processes?
Weathering takes place when rock is exposed to the Earths atmosphere and water. Rain, temperature changes and plants start to break it down by mechanical, chemical and biological processes. The produced fragments from weathering are removed by erosion and reduced in size during transportation. Transporting agents lose energy sooner or later e.g. Wind loses speed or a fast moving river joins a sea or lake. When this happens deposition occurs
What are the processes that occur below the Earths surface?
Sedimentary processes, metamorphic processes and igneous processes
What are the sedimentary processes?
Deposition usually occurs in lakes oceans and seas. Burial occurs as sediments are covered by more and more layers of sediments.
•as the sediments are buried more deeply and become compacted the grains of sediment are moved closer in contact due to the pressure above them
•water that circulates between the grains of sediment deposits minerals in the spaces between the grains. These and other changes that occur in buried sediments are part of the processes of diagenesis
•the growth of minerals in pore spaces and the compaction of grains results in the formation of sedimentary rocks
How are rocks effected by tectonic processes?
They can be exposed at the surface due to uplifting. Earths movements push rocks up by folding or faulting, so that rocks formed deep below the surface are now at the surface. Erosion over millions of years will expose rocks
What are the metamorphic processes like?
Metamorphism is caused when rocks are changed by heat and or pressure. It’s an isochemical process meaning that the chemical elements in the metamorphic rock are the same as those in the parent sedimentary rock. It involves recrystallisation - no melting takes place
What are the igneous processes like?
Melting is caused at depths where the temperatures are high enough, but different minerals have different melting points so that part of rock will melt whilst the rest remains solid (partial melting). Because it is hot and expanded, magma has a lower density than the rocks surrounding it and this caused it to rise and join with other rising magma. This magma accumulation creates underground magma chambers. The magma cools when it rises and forces its way onto joints or bedding planes etc. crystallisation may take place below the Earths surface surface. The rock cycle is completed when lava and pyroclasts are extruded at the Earths surface to form extrusive igneous rocks
