What is Earth Science?Earth Science is not so much a science as it is several sciences. When you study Earth Science you are really studying a mixture of Biology, Chemistry and Physics. Earth science has many areas of study, such as; Geology the study of the Earth's surface (rocks) and interior. Astronomy the study of the universe that the Earth is a part of. Meteorology the study of weather and the Earth's atmosphere. Oceanography the study of the earth's oceans. In this unit we will concentrate on the, ‘Chemistry bit,’ of Earth Science, i.e. Geology.
Journey to the centre of the Earth! If you started to dig a hole straight down about 13000 km later you would find yourself in Australia. What would you find on the way?
The Earth’s crust is made up of rocks and minerals. A mineral is just one pure substance. Rocks are a mixture of lots of bits of minerals together. How would you know if a material was a mineral or a rock? A mineral should be just one colour. However, even small amounts of impurity can give other colour tints. Rocks often look speckled because they are composed of many minerals.
IDENTIFYING MINERALS Use this information to identify the minerals shown on the picture cards given. MINERAL Chalcopyrite Calcite Fluorite Malachite Sphalerite Apatite Amethyst Azurite Bornite Quartz Galena APPEARANCE brassy yellow, metallic looking white-colourless, sometimes with streaks of colour colour very variable eg pale green, pale blue, cubic shape green, dull stony look black brown, metallic looking usually blue green, greasy appearance 6 sided prisms, purple deep blue red brown with streaks of blue Bright colourless glassy looking, irregular shape blue grey, metallic looking
APATITE CALCITE CHALCOPYRITE FLUORITE AZURITE AMETHYST GALENA MALACHITE QUARTZ BORNITE SPHALERITE
Different Types of Rock • There are three types of rock: • Sedimentary • Metamorphic • Igneous Each type of rock is formed in different way and have different properties.
Sedimentary Rocks. These are formed when water deposits layers of sediment (fragments of rock). Teacher Demo-muddy/sandy water
Examples include: • - Sandstone, which is made from compressed sand; • - Mudstone, which is made from compressed mud; • - Chalk and limestone, which is made from the compressed remains of plants and animals.
The rocks are slowly broken down into little bits by the weather, this is known as, ‘weathering.’ The bits of rock are then carried off by a river, wind or a glacier to another place. Eventually they settle as sediment. Over time layers of sediment pile up and pressure increases on the lower sediment particles. The pressure compacts the sediment together forming sedimentary rock.
Metamorphic Rock These are formed by the action of heat and pressure on other rocks.
Examples include: • slate (which used to be clay) • marble (which used to be limestone).
Igneous Rock These form when molten rock cools down to form crystals. If the molten rock cools slowly then large crystals form and if it cools quickly then small crystals form. Teacher demo – crystal size/cooling rate
Basalt Gabbro Granite Pumice
Watch video(249 “Rock Cycle” – 19 mins) Give out rock cycle sheet WS? (has above diagram)
Homework! Make a comic strip based on the Rock Cycle.
What is weathering? It is the breaking up of materials on the surface of the earth by weather. So is it really just the same as erosion? NO, erosion is actually the process of weathering and then water and wind carrying the resulting particles away.
There are actually many types of weathering: (1) Freezing • Water fills cracks in rock. • When it’s cold the water will freeze. • If this is repeated many times, the rock splits.
Could this also lead to weathering of the rock? *explain your answer* Homework –WS?(p125)