The Cycling of Matter Ch. 3 Lesson 4

Key Concept: Over time, matter- such as rock, water, carbon, and nitrogen- is transferred between organisms and the physical environment.

How fast does the earth change? Did you know that the Earth recycles? Since not much new matter comes into the Earth system, much that is here has to be recycled. Water, carbon, nitrogen, phosphorus, and even rocks move through cycles on Earth.

As matter moves through the Earth, it changes. Some changes are fast, like a flood moving a rock. Other changes are slow, like a tall mountain taking thousands of years to form. Since Earth is so old, even the slow changes affect Earth a great deal.

What are the Different Kinds of Rocks? Rocks are grouped by how they are formed. There are three groups: Sedimentary Rocks Igneous Rocks Metamorphic Rocks

Sedimentary Rocks Sedimentary rocks form when pieces of rock stick together to form a hard rock. Small pieces of rock that are moved from place to place by wind, water, ice, and gravity are called sediment.

Three types of Sedimentary Rocks Clastic Sedimentary Rocks are formed when sediment hardens under pressure. Chemical Sedimentary Rocks are formed when minerals that are dissolved into water formed crystals. Organic Sedimentary Rocks are formed when pieces of dead organisms stick together and form a rock.

Igneous Rocks Igneous rocks form when melted rock cools and hardens. They can be grouped based on the size of the crystals in the rock.

Igneous Rocks, continued Coarse-grained igneous rocks are formed when rock cools slowly and forms large crystals. Fine-grained igneous rocks form when rock cools quickly and only small crystals form or there is no time for crystals to form at all.

Igneous Rocks, continued Igneous rocks can also be grouped by the types of minerals in them. Some, like granite, are made mostly lightly-colored minerals and found on Earth’s crust, in the continents. Others are made of mostly dark-colored minerals and are found mostly in Earth’s mantle and in the crust under the oceans.

Metamorphic Rocks Metamorphic rocks form when rock changes because of heat or pressure. Most are deep within Earth’s crust, where the depths, temperature, and pressure can be much higher than at the Earth’s surface.

Metamorphic Rocks, continued Grouped according to how the minerals in them are related. In foliated metamorphic rock, the minerals form bands or stripes within the rock. In non-foliated metamorphic rock, the minerals do not form bands or stripes.

How Do Rocks Change from One Kind to Another? The Rock Cycle is made up of all the ways that rocks can change from one kind to another: Melting Cooling Heating Increasing pressure Weathering Erosion

Weathering happens when a rock is broken into smaller pieces. Erosion happens when sediment is moved from one place to another.

How Rock Moves Through the Rock Cycle Rock can take many paths through the rock cycle, depending on the forces that act upon the rock. The forces change, depending on where the rock is located. Example: metamorphic rock usually forms deep beneath Earth’s surface, where temperature and pressure is high.

How Water Moves Through Earth’s Systems The water cycle is the constant movement of water between the atmosphere, the land, and the oceans. Most of the energy that drives the water cycle comes from the sun.

How Elements Move Through the Earth’s Systems Many chemical elements, such as carbon, nitrogen, and phosphorus, are important for life on Earth. These elements are constantly moving from one place to another. They move between living things and nonliving things through many different processes.

The Carbon Cycle Carbon, an important part of many of the chemicals that make up living things, is found in the atmosphere, the land, and in water. The Carbon Cycle is the way the carbon moves between living and nonliving things.

The Carbon Cycle, continued Some parts of the carbon cycle happen fairly quickly. Example: Plants turn carbon dioxide from the atmosphere into food. Other organisms get food from plants. When plants and other organisms break down the food, the carbon dioxide moves back into the atmosphere. This process can take as little as a day or two.

Some parts happen very slowly. Example: Dead plants and tiny sea creatures can be buried by sediment before they decay. After thousands of years, the remains can turn into fossil fuels, such as coal, oil, and natural gas. The carbon in the organisms is stored in the fossil fuels. People can burn the fossil fuels for energy. When people burn the fossil fuels, the carbon moves back into the environment.

The Nitrogen Cycle The movement of nitrogen through the Earth system is called the nitrogen cycle. Nitrogen can be found in several different ways. In the atmosphere, it is mostly found as a gas, but since most living things cannot use nitrogen gas, special bacteria change it into a form of nitrogen that plants can use. Other organisms get their nitrogen from plants. When organisms die, the nitrogen in them can be returned to the environment. Bacteria can change the nitrogen in the dead organisms back into nitrogen gas. The nitrogen gas then moves back into the atmosphere.

The Phosphorus Cycle Like carbon and nitrogen, phosphorus is found in living things. It is also found in soil, rock, and water. Plants take up phosphorus through their roots from the soil. Animals take in phosphorus when they eat the plants. When plants and animals die, the phosphorus returns to the soil.

Other Cycles in Nature Many other forms of matter also move through the Earth in cycles. Almost all the elements that living things need to survive are cycled through Earth’s systems. When living things die, every element in their bodies is recycled. Every cycle in nature is connected to every other cycle. Example: water can carry nitrogen and carbon through the environment. Living things are also important to keep the cycles moving.