Leaving Cert Geography Rocks

Inorganic sedimentary rocks

Rocks formed from broken down particles of other rocks

Batholith

A mass of rock formed when a large body of magma cools inside the crust

sill

a slab of volcanic rock formed when magma squeezes between layers of rock

Lithification

sediments are compressed and water is squeezed out leaving only minerals

chalk

pure limestone

Coal

formed when dead vegetation is compacted by deposits of sand, silt and clay before it has decayed

The lower down in the earth's crust a stratum is

the older it is

Sandstone can be found in the

macgillycuddy reeks

Sandstone is an

inorganic sedimentary rock

Deposition

Process in which sediment is laid down in new locations

Cementation

The process in which dissolved minerals crystallize and glue particles of sediment together

Compaction

the process by which sediments are pressed together under their own weight

Shafting

Vertical tunnels are built to access and then excavate minerals that are underground and otherwise unreachable

Examples of sedimentary rocks

Limestone and sandstone

Examples of igneous rocks

granite and basalt

examples of metamorphic rocks

marble and slate

Marble can be found in

Connemara

Basalt can be found in

The giants causeway

When rocks form quickly the crystals are

Small

shafts

Vertical tunnels

dimension stone

Cut stone, used for surface veneers, toilet partitions, flooring, stair treads

Aggregates

Sand gravel and stone

Metamorphic rocks

are formed when igneous or sedimentary rocks are subjected to great heat and/or pressure.

As it changes form metamorphic rock is

compacted into a smaller volume

Metamorphic rocks are

more resistant to weathering or erosion than the original rock

Metamorphic rocks are formed in one of two ways.

Regional metamorphism or Contact metamorphism

Regional metamorphism

Friction at convergent plate boundaries creates great heat and pressure which change the composition and texture of rocks

Contact metamorphism

changes the composition and texture of rocks in a small surrounding area

Marble Characteristics:

coarse-grained hard rock

Marble Formation

formed when limestone or chalk changes as a result of regional metamorphism

During metamorphosis, calcite minerals in limestone are re-crystallised creating

a denser composed of interlocking calcite crystals