Rocks, weathering eroison and deposition 2 t sullivanPresentation Transcript
6th grade review Rocks, weathering, erosion, deposition and soil profile.
What is a rock? a lump or mass of hard consolidated mineral matter. Rocks are everywhere. They have been on the earth over four billion years. The rock you see might have once been part of a magnificent mountain or spectacular cave. It could have even been stomped by a dinosaur. Rocks are a fascinating way to discover information about the history of the earth. the 3 kinds of rocks are metamorphic ,igneous and sedimentary.
Metamorphic rocks Metamorphic rocks-Are rocks that have "morphed“(or changed) into a different kind of rock. Metamorphic rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change? The rocks are under a ton of pressure, which fosters heat build up, and this causes them to morph (or change). If you exam metamorphic rock samples closely, you'll discover how flat some of the grains in the rocks are. Types and examples-Amphibolites Gneiss Marble Phyllite Quartzite Schist
Igneous rocks Igneous rocks-Igneous rocks are called fire rocks and are formed either underground or above ground. Underground, they are formed when the melted rock (called magma) deep inside the earth surface becomes stuck (or trapped) in small pockets. As these pockets of magma cool very slowly underground, the magma becomes an igneous rocks. This is an example of an intrusive rock. Igneous rocks are also formed when volcanoes erupt, causing the magma to rise above the earth's surface. When magma is above the earth, it is called lava. Igneous rocks are formed as the lava cools above ground. This is an extrusive rock.
Sedimentary rocks Sedimentary rocks- For thousands, even millions of years, little pieces of earth have been eroded--broken down and worn away by wind and water. These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock. Types and examples- Sandstone Limestone Shale Conglomerate Gypsum
Weathering Weathering causes the disintegration of rock near the surface of the earth. Plant and animal life, atmosphere and water are the major causes of weathering. Weathering breaks down and loosens the surface minerals of rock so they can be transported away by agents of erosion such as water, wind and ice. There are two types of weathering: mechanical and chemical.
Mechanical weathering Mechanical weathering is the disintegration of rock into smaller and smaller fragments. Frost action is an effective form of mechanical weathering. When water trickles down into fractures and pores of rock, then freezes, its volume increases by almost 10 percent. Exfoliation is another form of mechanical weathering in which curved plates of rock are stripped from rock below.
Chemical weathering Chemical weathering transforms the original material into a substance with a different composition and different physical characteristics. The new substance is typically much softer and more susceptible to agents of erosion than the original material. The rate of chemical weathering is greatly sped up by the warm temperatures and moisture. Also, some minerals are more vulnerable to chemical weathering than others. For example, feldspar is far more reactive than quartz.
erosion Erosion is the process by which the surface of the Earth gets worn down. Erosion can be caused by natural elements such as wind and glacial ice. But anyone who has ever seen a picture of the Grand Canyon knows that nothing beats the slow steady movement of water when it comes to changing the Earth. The key to erosion is something called "fluid flow." Water, air, and even ice are fluids because they tend to flow from one place to another due to the force of gravity. Of the three, liquid water is the most common agent of erosion because there's so much of it on the surface of the Earth.
deposition the term deposition refers to the settling out or placement of rock, particles of rock, or organic matter, generally referred to as sediments, after transportation by wind, water, ice, or gravity. Deposition occurs when the energy causing the transportation of sediments becomes unable to move the sediments any further due to its weight or friction with other particles.
Soil profile O Horizon: (1st layer) This is the top layer of soil. Animals live on this layer. It is made of fresh to partially decomposedorganic matters. The color varies from brown to black.A Horizon: (2nd layer) The top part of this soil is made of highly decomposed organic matter mixed up. The color range from brown to gray. E Horizon: (3rd layer) This layer is made up of mostly sand and silt it have lost most of its minerals and clay due to eluviation. B Horizon: (4th layer) Unlike the other horizons, this one has more clay and bigger bedrock. It is reddish brown or tan in color. C Horizon: (5th layer) This layer have mostly weathered bedrock. It is the cracked and broken surface of the bedrock. R Horizon: (Last Layer) This is the last layer in the profile. It is made of unweathered rocks.