Unit E: Planet Earth Topic 1: Scientific Study Helps Us Understand the Earth

Transcription

1 Unit E: Planet Earth Topic 1: Scientific Study Helps Us Understand the Earth 1

2 1.1 A Model for Earth A. Our Ancient Past 1. Geologists estimate that the Earth is about billion years old 2. Humans appeared on Earth s surface about million years ago B. Developing a Model 1. A model is an idea of something that can t be fully or seen 2. It is a way of demonstrating an object or an idea that is difficult to in its real form C. What s Inside the Earth 1. Geologists a) Scientists that Earth b) They use a model to help them understand Earth s structure 2. Earth s Interior a) Inner i. Mainly iron and nickel ii. Reaches temperatures as high as C 2

3 b) Outer Core i. Thought to be because the pressure isn t great enough to turn the molten rock into a solid c) Mantle i. Makes up two-thirds of Earth s d) Crust i. Everything we see is the crust: mountains, valleys, plains, hills and ii. It s km thick Iron ore Coal D. The Crust 1. It s the that covers Earth s surface 2. All living things live 3. It is a rich storehouse of (iron and copper ore) 4. It s where we get the fuels (oil, natural gas and coal) 5. Average thickness is km 6. Vegetation is only a covering 7. It s made up of solid 3

4 Topic 1.1 Review 1. Do you think any of these would make a good model for Earth s interior? Give reasons for your answers. 2. Give two examples where models are used to serve different purposes. 3. Make and label a drawing showing Earth s layers as you would see them if a wedge were cut from Earth. Do your best to make the drawing to scale. 1.2 Earth s Gradual and Sudden Changes A. Earthquakes 1. Earthquakes are trembling's or of the ground 2. Caused by a sudden release of that has been slowly building up in Earth s crust 3. Focus the first place where the rocks below the surface in an earthquake 4. The energy that is released from the focus spreads out as through Earth 4

5 5. Seismic waves earthquake waves that are released at the 6. The shaking you feel during an earthquake is caused by the seismic waves moving the ground 7. Epicenter the point on the surface directly the focus B. Measuring Earthquakes 1. Seismograph a) A device that the waves of energy that spread through Earth from the focus of an earthquake 2. Richter a) When you hear about the of an earthquake, it s given as a number on the Richter Scale b) The scale starts at c) Each increase of 1 represents an increase of times the amount of ground motion Example #1: An earthquake of Richter magnitude 3 is times stronger than one that measures 2. Example #2: An earthquake of Richter magnitude 6 is times stronger than one that measures 3. 5

6 C. Volcanoes 1. An in Earth s crust through which solid and molten rock, ash, and gases escape 2. Molten rock, or, forces its way up through a weakness in Earth s crust 3. Lava flows from the side of the volcano or into the air as a cloud of rock fragments and ash 4. Lava and rock fragments move downhill because of D. Tools and Techniques for Earth 1. Geologists studying volcanoes must wear a special suit with a coating that reflects these intense temperatures. 6

7 a) This allows them to get enough to an eruption to make observations, take measurements, or collect gas and lava samples 2. Some volcanoes outward slightly when the pressure from rising molten rock inside them builds up a) These signs, not visible to the naked eye, can be detected using a level, a device that measures minute changes in the angle of the ground s slope E. Weathering, Erosion and Deposition 1. Weathering a) Refers to the mechanical and chemical process that down rocks by means of water, glacial ice, wind, and waves 2. Erosion a) Occurs when the products of weathering are from place to place 7

8 3. Deposition a) The process of these being laid down or deposited by wind, water, and ice F. Effects of Moving Water 1. Rivers flowing through soil fine grains and carry them, making the water look muddy. 2. Sediment the silt, sand, mud and gravel that rivers as they flow 3. Sedimentation a) The process of sediments being, usually at the bottom of oceans, lakes and rivers 4. Landslides a) Sudden and fast of rocks and soil down a slope b) They usually happen when on the side of a hill gets soaked with water 8

9 5. Glaciers a) A moving of ice and snow b) Ice once covered to heights of 600-1,000 m c) As glaciers flow, they pick up large fragments that act as grinding tools to carve and scrape landscapes Big Rock, near Calgary Topic 1.2 Review 1. What is believed to be the cause of earthquakes? 2. Why do you think it is difficult to predict earthquakes? 3. What are some instruments and equipment used to investigate earthquakes and volcanoes? 4. Explain the relationship between erosion and weathering. Give some examples of weathering. 5. How does moving water change the landscape? 6. What might happen to a riverbed if sediments are deposited? 7. How do glaciers change the landscape? 9

10 1.3 Rocks and Minerals A. Rocks 1. Made up of many little particles called B. Minerals 1. The building blocks of rocks that are pure, naturally occurring solid 2. All rocks are made of minerals like limestone (made of mineral) or granite (made of different minerals) Limestone Granite Feldspar Calcite Quartz 3. There are more than different minerals 4. Just minerals combine in different ways to form the majority of rocks in the Earth s crust: a) b) c) d) e) Mica Hornblende 10

11 C. Using Properties to Identify Minerals 1. Properties the that a material or object has 2. Lustre a) The way the of a mineral reflects light 3. Cleavage a) If a mineral splits easily into smooth surfaces, it is described as cleavage 4. Fracture a) A break with rough and uneven surfaces D. Mohs Scale of Hardness 1. The hardness of a mineral is measured by how easily it can be 2. Mohs Scale of Hardness consists of minerals ranked in order of hardness. Diamond is the hardest 11

12 Topic 1.3 Review 1. One of the steps in identifying a rock is to identify the minerals it contains. For example, granite is made of quartz, feldspar, and mica. If you were given an unknown rock, how would you use what you learned in this section to identify it? 2. The properties of minerals are useful for more than just identifying them. Sometimes, properties make a mineral valuable. For example, colour is important in gemstones. What other property that you learned about in this subsection might make a mineral useful or valuable? 12