The rock cycle (1)

Sedimentary RockSedimentary rocks form at or near the earth's surface at relatively low temperatures and pressures primarily by: deposition by water, wind or ice precipitation from so

The Rock Cycle

By:

Sarah Dowling Rupa Kamboj Joy Kim Tony Tavlian Jean Young

Basics The Rock Cycle is a group

Metamorphic rock can change into igneous or sedimentary rock

Sedimentary Rock

Sedimentary rocks form at or near the

earth's surface at relatively low

temperatures and pressures primarily by: deposition by water, wind or ice

precipitation from solution (may be

biologically mediated)

growth in position by organic processes (e.g., carbonate reefs )

Metamorphic Rock

Metamorphic Rock is formed when rocky material

experiences intense heat and pressure in the crust of the

Pause Here

Sediment can either be:

Material, originally suspended in a liquid, that settles at the bottom of the liquid when it is left standing for a long timeMaterial eroded from preexisting rocks that is transported

by water, wind, or ice and deposited elsewhere

Plutonic and Volcanic Rock

Volcanic rocks, a.k.a extrusive rocks or lava

rocks, crystallize when the magma reaches the earth’s surface cooling quickly.

Plutonic or intrusive rocks crystallize within the crust of the earth, and as a result plutonic rocks cool at a much slower pace then volcanic rocks

Melting is the result of continued heating

Leads to production of magma and new igneous rocks which are formed when the the magma cools

This process depends on the size of the reservoir that it drains and the relative intensity or activity of plate tectonics

Heat and Pressure

Metamorphic rocks trapped underground are still subject to enormous heat from rising magma, or heated water, and pressure Sometimes the heat can get so intense the rocks actually melt

Pressure comes from the incredible weight of material

surrounding the rock on all sides

The pressure pushes new minerals into the rock and drives other minerals out; the result, of course, is that the rock is chemically changed

The process in which rocks are broken down by chemical and/or physical mechanisms into smaller particles

There are three types of weathering

Physical weathering: physical action which breaks up rocks An example of this is freethaw weathering

Chemical Weathering: when the rock is attacked by chemicals An example of this is how acid rain breaks down limestone

Biological weathering: occurs when rocks are

weakened and broken down by animals and plants A tree root system that is slowly splitting rocks is an

example of this type of weathering

Erosion is the wearing away of exposed surfaces by agents such as wind, moving water and ice These agents usually contain weathered rock debris Rock fall under gravity is also erosion

Erosion influences orogenesis by changing the topography and hence the thickness of the deforming orogen, which, in turn results in modification of the gravitational force

relative to the tectonic driving force Whereas efficient

erosion tends to localize deformation within a relatively narrow belt, decrease in erosional efficiency causes

deformation to propagate toward more distal sites

A rock that gets caught up in the subduction zone may get dragged down with the oceanic plate

As the rock gets dragged down, they undergo metamorphism

Some parts of the rocks get taken all the way down to the

mantle where they slowly mix with the rest of the mantle – this

is the only way that rocks formed on the continent get recycled with the mantle

The result of this pressure

is a compaction of the sediment

it is squeezed together causing a reduction in pore space and a sticking together of the grains

Under pressure, some chemical sediments, like halite, may recrystallize into a solid state

The water flows through

the sediment and some of

these minerals precipitate

on the grain surfaces

With time, this

intergranular material

effectively glues the

sediment together into a

cohesive solid- a

sedimentary rock

Because certain rocks are created under the Earth’s surface A process called uplifting occurs through orogeny and volcanic

process, which then bring rocks to the

surface The rock is eventually becomes

recycled again.

This process occurs when the particles created by weathering are carried by ice, air, or water to a region of lower energy known as a sedimentary basin

Decomposition takes place when a lowering

of hydraulic energy, organic biochemical

activity, or chemical changes occur.

When hot conditions that caused magma to melt will cool, either

because the source of heat subsides or the magma moves into cooler regions of the Earth

When it gets cool enough the minerals that will make up the rock

begin to crystallize and form an intergrown mass of crystals

If the crystals begin to form deep in the Earth where it is relatively warm the magma cools slowly allowing the crystals to grow relatively large.

If the magma reaches the surface, the lava cools quickly and the

crystals do not have time to grow very large

If the crystals cannot grow at all and volcanic glass is formed

An earthquake is the shaking of

the Earth’s surface caused by

the rapid movement of the

Earth’s rocky outer layer

Earthquakes occur when energy

stored within the Earth, usually

in the form of strain in rocks,

suddenly releases

This energy is transmitted to

the surface of the Earth by

earthquake waves or seismic

tremors.

Most earthquakes are

caused by the sudden slip

along geologic faults

because of movement of

the Earth’s tectonic plates

The rocky tectonic plates move very slowly, floating

on top of a weaker rocky layer

As the plates collide with each other or slide past each other, pressure builds

up within the rocky crust Earthquakes occur when pressure within the crust increases slowly over hundreds of years and finally exceeds the strength of the rocks

The Earth is made up of plates.

There are 2 kinds of plates:

Near the surface, it is composed of rocks that are felsic (made

up of minerals including feldspar and silica)

Deeper in the continental crust, the composition is mafic

(made of magnesium, iron, and other minerals)

Oceanic Plate

Oceanic crust makes up 60 percent of the earth’s solid surface

Oceanic crust is thin and dense Oceanic crust averages between 5 and 10 km

(between 3 and 6 mi) thick

It is composed of a top layer of sediment, a middle layer of rock called basalt, and

a bottom layer of rock called gabbro

Basalt and gabbro are dark-colored igneous, or volcanic, rocks

It is constantly produced at the bottom of the oceans in places called mid-ocean ridges—undersea volcanic mountain chains formed at plate boundaries where there

is a build-up of ocean crust

This production of crust does not increase the physical size of the earth, so the material produced at mid-ocean ridges must be recycled, or consumed, somewhere else

Oceanic crust is continually recycled so that its age is not greater than 200 million years

Plate collision where the oceanic plate (crust) will slide beneath the continental plate (crust) because it is more dense than the continental plate

A plate collision where the continental plates (crusts) collide Thus, they have to go up.