Chapter 5: The Rock Cycle Plutonic rocks Formed within the Earth Intrusive e.g. granite

Chapter 5: The Rock Cycle Volcanic rocks Formed at the surface of the Earth Extrusive e.g. basalt

Chapter 5: The Rock Cycle The rock cycle Rocks continually form, change, are destroyed and reconstituted Endogenic forces – construct and modify Exogenic forces – destroy Deposition – reconstitute

Chapter 5: The Rock Cycle Magma Rock layers subduct into the crust and mantle Rock layers melt and form molten rock

Chapter 5: The Rock Cycle Rocks vary in their: Origin Formation Characteristics

Chapter 5: The Rock Cycle Three major rock groups exist: Igneous Sedimentary Metamorphic

Chapter 5: The Rock Cycle Rock Formation 1.Igneous Magma rises, cools and solidifies to form igneous rocks Magma reaches the surface, it forms volcanic rock Magma cools and hardens within the crust, it forms plutonic rock

Chapter 5: The Rock Cycle Rock Formation (continued) 2. Sedimentary Destroyed where denudation occurs on the surface Weathering Erosion Break down into sediments Sediments are then deposited and compressed

Chapter 5: The Rock Cycle Rock Formation (continued) 3. Metamorphic Modified due to either great heat or pressure or both

Chapter 5: The Rock Cycle Characteristics of the different types of rocks 1.Igneous rock Two types: I. Plutonic or intrusive rocks Formed when magma cooled down and solidified inside the Earth’s crust e.g. granite II. Volcanic and extrusive Formed when lava cooled and solidified on the Earth’s surface or close to the surface e.g. basalt

Chapter 5: The Rock Cycle Igneous rocks contain crystals Size tells length of time it took rock to cool Large crystals cooled slowly within the Earth’s crust Small crystals, cooled quickly on the Earth’s surface

Chapter 5: The Rock Cycle Granite Coarse-grained Formed when magma cooled deep within the Earth’s crust Contains minerals of feldspar, quartz and mica Varies in colour – white, grey, pink or black Crystals are large, the rock cooled slowly e.g. Wicklow Mountains

Chapter 5: The Rock Cycle Basalt Fine-to-medium-grained Ranges in colour – black to dark grey Formed when lava cooled quickly on the Earth’s surface Small crystals e.g. Antrim-Derry Plateau Giant’s Causeway Six-sided columns, hexagonal in shape

Chapter 5: The Rock Cycle Characteristics of the different types of rocks 2. Sedimentary rock Formed over millions of years Rock fragments and the remains of animals and plants compressed under pressure to form solid rock e.g. limestone and sandstone

Chapter 5: The Rock Cycle Two types of sedimentary rock i. Inorganic sedimentary rock Inorganic sedimentary rock formed from the broken down remains of pre-existing rock ii. Organic sedimentary rock Organic sedimentary rock formed from the remains of animal and plant life

Chapter 5: The Rock Cycle Limestone Organic sedimentary rock Most common type of rock in Ireland Cemented and compressed remains of fish and other sea creatures Over millions of years compressed and formed slowly into solid rock Carboniferous period Contains calcium carbonate Varies in colour - greyish white, black, dark grey e.g. the Burren in Co. Clare

Chapter 5: The Rock Cycle Sandstone Inorganic sedimentary rock Coarse Usually brown or red Formed approximately 400 million years ago Sediments laid down in layers Each successive layer compressed the next layer Cemented to form sandstone e.g. Comeragh Mountains, Co. Waterford

Chapter 5: The Rock Cycle Characteristics of the different types of rocks 3. Metamorphic rock Formation: Sedimentary or igneous rocks changed by either great heat or pressure (or both) Magma Folding Appearance, texture and chemical composition change

Chapter 5: The Rock Cycle Types of metamorphism i. Thermal heat alone rocks change in composition ii. Regional great heat and pressure over a large area fold mountain colliding plates rising magma

Chapter 5: The Rock Cycle Examples of sedimentary rock changing into metamorphic rock Limestone changes to marble, e.g. Connemara in Co. Galway Sandstone changes to quartzite, e.g. Sugarloaf Mountain, Co. Wicklow

Chapter 5: The Rock Cycle Marble Metamorphic rock Limestone Heat and pressure Various colours Connemara (green) Kilkenny (black) Cork (red) Rathlin Island, Antrim and Carrara, Italy (white)

Chapter 5: The Rock Cycle Quartzite Metamorphic Sandstone Heat and pressure Mountain building Sandstone came into contact with magma Light-coloured rock, e.g. Croagh Patrick, Co. Mayo

Chapter 5: The Rock Cycle Active plate margins Oceanic plate subducting under a continental plate Faulting, mountain building, volcanoes and earthquake activity e.g. west coast of North America Pacific plate subducting under North American plate

Chapter 5: The Rock Cycle Trailing plate margin Absence of earthquake, volcanic activity or folding Sedimentary rocks form, e.g. sandstone and limestone

Chapter 5: The Rock Cycle Quarrying case study Important resource Energy Building materials

Chapter 5: The Rock Cycle 1. Methods of quarrying I. Plug and feather drilling holes split the rock extracting large pieces, e.g. floor covering II. Explosive extracting large and small pieces of rock III. Channelling machinery cuts large slices of rock metamorphic rock such as marble

Chapter 5: The Rock Cycle 2. Positive impacts of quarrying Direct employment Construction Indirect employment

Chapter 5: The Rock Cycle 3. Negative impacts of quarrying Visual pollution Noise pollution Heavy machinery damage to infrastructure Dust pollution Water pollution Disused quarries

Chapter 5: The Rock Cycle 4. Carrara marble Tuscany, Italy White or blue-grey marble Used since the time of ancient Rome Statue of David – Michelangelo Exported all around the world Construction of buildings Warm countries Reflect light Create an air of coolness