Unit 4

Bell ringer 10/10/16 Correct Answer: B. Wind Sand dunes are large piles of sand that can be found in the desert. What causes these sand dunes to form? A. Water B. Wind C. Earthquakes D. Volcanoes Correct Answer: B. Wind

Bell ringer 10/11/16 Correct Answer: C. Breaking down rocks Weathering of Earth’s surface can have which of the following effects? A. Building mountains B. Creating hurricanes C. Breaking down rocks D. Causing lava flow Correct Answer: C. Breaking down rocks

Bell Ringer 10/12/16 Canyons are formed by- A. Earthquakes breaking rock layers apart B. Wind smoothing out rock formations C. Lava flowing from nearby volcanoes D. Rivers carrying sediment that erode land Correct Answer: D. Rivers carrying sediment that erode land

Bell Ringer 10/13/16 Correct Answer: D. Delta Sediments, which are deposited at the mouth of a river, create a- A. Lake B. Volcano C. Canyon D. Delta Correct Answer: D. Delta

Bell Ringer 10/14/16 Correct Answer: A. Glaciers A valley will take on a U-shape as a result of the movement of- A. Glaciers B. Wind C. Lava D. Sand Correct Answer: A. Glaciers

7.8A Catastrophic Events

Student Expectation: The student is expected to predict and describe how different types of catastrophic events impact ecosystems such as floods, hurricanes, or tornadoes.

Floods Floods result when rainfall exceeds the holding capacity of a drainage system. The energy of the moving water and the layers of sediment carried by the water can uproot or bury plants, reshape the topography, and destroy roads and buildings. Flooding can also occur in cities when sewers and runoff catchments cannot keep up with the amount of rain. Often streets are the first to flood in this situation, and waters will continue to rise until the rains stop and the water is given time to drain. Buildings with basements, tunnels, or houses at low elevations are susceptible to flooding.

Hurricanes Hurricanes develop over warm ocean waters as an area of low pressure in the atmosphere.  As more ocean water evaporates, air pressure decreases and wind intensity increases. Hurricanes have a negative impact the ecosystem as intense wind damage and excess flooding all along the path of the storm. Surges of salt water can destroy plant life.

Tornadoes Tornadoes are violent, rotating columns of air extending from the base of intense storm clouds.  Although affecting an area much smaller in width and distance than that covered by a hurricane, tornadoes have much stronger wind speeds. Objects in the path of a tornado are totally destroyed, leaving a scar of devastation to the ecosystem.

7.8B Changes to Texas Land

Student Expectation: The student is expected to analyze the effects of weathering erosion, and deposition on the environment in eco-regions of Texas.

Mechanical Weathering Mechanical or physical weathering is the process by which rock is broken down into smaller pieces by physical changes. Some ways that rock can be broken down physically include: Temperature Change – a rise in temperature will cause a rock to expand, and a decrease in temperature will cause a rock to contract. Repeated changes in temperatures will cause the rock to crumble.

Abrasion Rock can be broken down by the action of other rocks; wind, water, glaciers, and gravity carry different sized pieces of sediment that can strike a rock causing it to break apart or wear down.

Partner Discussion: Describe the effect of wind erosion on a desert ecosystem. Your answer should include ways the surface of the Earth might change and how these changes would affect both plants and animals. The flow of wind or water can displace both topsoil and deeper dirt, which leads to shifting nutrients and resources. The displacement of soil leads to the burying of seeds, which can slow or block new plant growth. Soil and sediment can also be washed into rivers and streams, which clog up the habitats of animals living nearby.

Animal Actions Animals digging and burrowing can cause rock to break apart of become more exposed to other agents of weathering.

Plant Growth Roots of plants break apart rock as they grow and increase in size.

Chemical weathering The breakdown of rocks by chemical reactions. Occurs more often in locations with high precipitation rates and high temperatures.

Oxidation When materials in rock react with the oxygen in air or water causing a chemical change. Examples include rusting and corrosion.

Natural Acids Some acids form naturally when chemical in the atmosphere combine with water in the air and cause acid precipitation. The acid precipitation weathers rock and changes its composition. Carbonic acid can also form when carbon dioxide dissolves in water. When carbonic acid comes into contact with some rocks, it causes a reaction that breaks the rock down chemically.

Partner Discussion: What human activities can increase the rate of weathering? Humans cause increases in acid rain and pollution, which increase the amount of weathering agents in the air and water, and then on land.

Acids from Organisms Certain living organisms produce acids that break down rock. Lichen and mosses produce weak acids that break down the rock that they grow on.

Partner Discussion: Why is the exposed rock surface more weathered than the interior of a rock? The majority of weathering processes involve exposure to the elements of water and atmospheric gases. The interior rock is less exposed to these elements than the surface rock.

Partner Discussion: Why are the agents of erosion and deposition the same? Erosion is the process of transporting Earth material by the erosional agents of wind, water, ice, or gravity. The obvious final step in the erosion process is deposition of the material in a new place. Erosion and deposition are not separate operations, but rather the beginning and end to a single process of transportation of sediment.

7.8C Watershed

Groundwater The water that is held under the Earth’s surface is called groundwater. Surface water can become groundwater by infiltrating, or sinking, below the surface. Groundwater can be stored in and move through layers of rock known as aquifers.

Porosity A rock layer is a good aquifer if it has high porosity and high permeability. High porosity means that there are many pores, or spaces, in the rock where water can reside. High permeability means that these pores are well connected, allowing water to flow through the rock.

Partner Discussion: A local government wants to build a landfill on the outskirts of a town. Many people in the town are against the landfill because they think it will pollute their water sources. The local government argues that the landfill will be built above ground in a place where runoff cannot occur. Explain how the landfill might still have negative effects on the local watershed. The pollution from the landfill can still seep into the ground and pollute the water sources held within the aquifer.

Aquifers One of the ways we get drinking water is by drilling wells into aquifers and pumping the water to the surface. Unfortunately, we can deplete our drinking water supplies if we pump water out faster than rain can infiltrate the ground and replenish it. Also, when we pump out too much water, the pore spaces in the rocks, which are used to hold water, shrink in size. This shrinkage leads to subsidence, or the sinking of Earth’s surface.

Watershed A watershed, also known as a drainage basin, is the area of land that funnels all of its surface water and groundwater into a body of water, such as a stream, river, lake, aquifer, or ocean. Areas of high ground separate watersheds from each other.

Pollution Human activities can also lead to pollution of Earth’s groundwater and surface waters. Water pollution is either point source or non-point source. If water pollution is point source, we can trace back to the source of pollution If pollution is non-point source, there is not an apparent single source of pollution. Point source pollution

Partner Discussion: Name and describe two human activities that have different negative effects on groundwater held in aquifers. Describe how each affects the groundwater or the aquifer in its own way. Pollutants from human activities, such as fertilizing crops, dumping waste from factories, or debris from construction enter the watershed and pollute water that seeps through the ground into aquifers. Excess pumping of the groundwater for human use cause the pores in the aquifer to shrink resulting in weakness that can lead to subsidence, or ground sinking.