Rocks Presentation PDF

# Rocks ## Intrusive Rocks - **Granite** - **Colour:** Range of colours, including black, grey, pink and cream - **Texture:** Coarse grained - **Formation:** Formed when molten magma pushes its way into the crust and cools and hardens there, under the surface. Granite has large crystal...

# Rocks ## Intrusive Rocks - **Granite** - **Colour:** Range of colours, including black, grey, pink and cream - **Texture:** Coarse grained - **Formation:** Formed when molten magma pushes its way into the crust and cools and hardens there, under the surface. Granite has large crystals because the molten magma cooled very slowly over millions of years. These crystals include the minerals quartz, feldspar and mica. Granite is eventually exposed at the surface when rock lying over it is worn away. - **Use:** Used in a variety of everyday products such as counter tops in kitchens because of its hardness and durability. - **Example:** Found in the Mourne Mountains in the east of Ireland. ## Metamorphic Rocks - **Marble** - **Colour:** White/red/green/black - **Texture:** Smooth - **Formation:** Formed when limestone is put under great heat or pressure due to plate movement or when molten magma comes in contact with limestone. It's a very hard rock that can vary in color. - **Use:** Can be cut to whatever size is required and polished to make its appearance appealing, used to make monuments, floor tiles, fireplaces and ornaments. - **Examples:** Found in Co. Antrim (white), Co. Cork (red), Connemara, Co. Galway (green) and Co. Kilkenny (black). - **Quartzite** - **Colour:** White/grey - **Texture:** Granular (grainy) - **Formation:** Formed when sandstone is put under great heat or pressure due to plate movement or when molten magma comes in contact with sandstone. It's an extremely hard rock and is found on the top of many of Ireland's mountains because it's not easily broken down. - **Use:** Used in objects such as counter tops and road chippings, and to make glass. - **Examples:** Croagh Patrick in Co. Mayo and the Great Sugarloaf in Co. Wicklow. ## Extrusive Rocks - **Sandstone** - **Colour:** Reddish/brown - **Texture:** Coarse grained - **Formation:** Formed from sand that has been worn away from the Earth's surface. This sand is carried by the wind and rivers and then deposited as sediment in seas, lakes and deserts, where the layers build up over time. The layers are compressed and cemented together to form sandstone. - **Use:** Used in patios and as a building material in the construction industry. - **Examples:** Found in MacGillycuddy's Reeks in Co. Kerry and the Galtee Mountains in the south of Ireland. - **Limestone** - **Colour:** Grey - **Texture:** Coarse grained - **Formation:** Formed about 350 million years ago when Ireland was located close to the equator. Limestone is made from particles of shells and the remains of skeletons of sea creatures. When these particles sink to the seabed they are called sediment. The sediment piled up at the bottom of a warm, shallow sea over millions of years. The weight of the upper layers of sediment compressed and cemented the lower layers of sediment into strata (layers) of solid rock. - **Permeable:** Water can pass through it. - **Soluble:** Dissolves in water. - **Use:** Often used to make monuments. It is used in the construction of buildings, and to make cement. It is also ground down into lime and added to soil to improve soil fertility. - **Example:** The most common type of rock in Ireland. It is found in The Burren, one of the biggest tourist attractions in the west of Ireland. - **Basalt** - **Colour:** Grey/black - **Texture:** Medium grained - **Formation:** Formed when lava spreads out over the surface of the Earth's crust due to volcanic activity. It then cools and hardens. Basalt has tiny crystals which cannot be seen without the use of a microscope. This is because the lava cooled and hardened very quickly in the open air when it reached the surface. - **Use:** Used for road chippings due to its hardness. The landscape created by basalt can also be a tourist attraction. - **Example:** Found in the Antrim-Derry Plateau in the north-east of Ireland. The Giant's Causeway is part of this plateau. As the lava there was so thick, when it cooled it contracted to form the hexagonal (six-sided) shapes that can be seen today.