Name: edHelper Principles of Relative-Age Dating Have you ever heard the phrase "older than dirt"? Can anything be older than dirt? The answer is yes! Dirt is formed as layers of rock are eroded away. Some layers of rock are older than others. A process called relative-age dating helps scientists determine how old these rock layers are. This has also helped them to know how old the Earth is. Relative-age dating helps scientists put Earth's historic events in order. They compare one event or rock layer to another. There are many principles that help scientists with this process. One principle is called original horizontality. This simply means that sediments are usually deposited in horizontal layers. As the layers build up, they cement together to form sedimentary rocks. While looking at rock layers, scientists can use another principle to help determine relative age. This is called the law of superposition. This law assumes that each layer of sediments has been deposited at a different time. Layers on the bottom are deposited first. The younger layers are on the top. This principle only works, of course, for sedimentary rocks that have not been disturbed. A principle that helps scientists determine relative ages of disturbed rock layers is called cross-cutting relationships. This rule is used with igneous intrusion, when there is a fault. A fault is a crack in a rock layer. Movement takes place at a fault. This rule states that a fault is younger than the rock it cuts across. For example, scientists may discover a layer of schist. In a certain area, a layer of granite cuts across it along a fault. The principle of cross-cutting relationships helps scientists to know that the granite is younger than the schist. The granite has intruded into the schist. Erosion can make relative dating difficult. There is a geological principle that helps scientists with these problems, however. When a layer of rock is eroded, some of the particles are carried away. The loose material on the surface may mix with the new layer deposited on top. This is called an inclusion. Scientists must learn to identify inclusions and then focus on the rock layer on the bottom, knowing that it is older than the one on top. Another way to determine relative age is by correlation. This is a way for scientists to match rock layers that are found far from each other. Geologists carefully examine the rocks. They look for unique fossils and other features. This helps them compare the layers. The process of relative-age dating is based on the idea that sediments have been deposited in the same way since the beginning of time. Imagine standing on the bank of a river. The water flows by, depositing sediments along the bottom. This process has always happened the same way. This is called the principle of uniformitarianism. Name: edHelper Scientists once used this principle as a means to determine the age of the Earth. However, other methods have since proved to be much more accurate. Even though this principle cannot be used to determine the age of objects, scientists still use relative-age dating to compare rock layers. They can tell if one rock layer is older or younger than another. The relative age of something is not exact. Scientists use other methods if they need to know the exact age of a rock. Principles of Relative-Age Dating Questions 1. What does the principle of original horizontality state? A. A fault is younger than the rock layer it cuts across. B. Sediments are deposited in horizontal layers. C. Each layer of sediments has been deposited at a different time. 2. The law of superposition only works for: A. layers that have been eroded B. layers that have been faulted C. layers that have not been disturbed 3. When eroded material mixes with a new rock layer deposited on top of it, it is called: A. correlation B. an inclusion C. relative-age dating 4. What does the principle of uniformitarianism state? 5. Scientists use relative-age dating to do what? 6. Using relative-age dating, scientists can tell the exact age of a rock. A. false B. true Round the decimal 0.435 to What is the area of a 36 + n = 55 the nearest hundredth. rectangle with sides 4 cm and 6 cm? edHelper Name: Explain why the principle of superposition only works with rock layers that have not been disturbed. Don't stop writing. Use a blank piece of paper to continue. Name: edHelper Pizza For Sale Where and when was pizza first made? Experts cannot seem to agree on an exact place and time. They do agree that pizza was not first made in the United States. Pizza appeared in the U.S. in the late nineteenth century. Italian immigrants began selling it in their neighborhoods in large cities. In Chicago, a pizza maker would walk up and down the streets. He would carry pizzas in a large metal washtub on his head. Experts say that was the way that pizzas were sold in Naples, Italy. Pizzas then began to appear in grocery stores and small cafes. Gennaro Lombardi is given credit for having the first official pizzeria in the U.S. It was in New York City. Lombardi's business began as a grocery store in 1897. He then opened a pizzeria in 1905. A whole pizza could be bought for five cents. Many people could not afford that. Instead, they were asked what they could afford. They were given slices according to that amount. Many pizzerias have opened over the years. Home delivery has become popular. Pizza is a favorite food of many. Pizza For Sale Questions 1. Pizza was first made in the United States. A. true B. false 2. According to many experts, which group of people first sold pizza in the United States? A. German immigrants B. Italian immigrants C. Irish immigrants D. Russian immigrants 3. Describe how pizza was first sold in Italian neighborhoods. 4. Who is Gennaro Lombardi? Name: edHelper 5. What type of business did Gennaro Lombardi first have? A. a pizza restaurant B. a grocery store C. a deli D. a bakery 6. How much did Gennaro Lombardi charge for his pizzas? The vowels are missing in the word search. Write the missing family fact. Fill in the missing vowels and circle the words. 159 - 91 = 68 M R C V C 91 + 68 = 159 159 - 68 = 91 D E W D S N M D R R C How many feet are in 5 yards? N S U L T L L feet T N C P G D R T T T N H V Gavin took three numbers greater than 1 and multiplied them. One number was five C T I G T F C and the other number was fifteen. Of course, he forgot the last number, but he O N R remembered the product was 107. Is this possible? L L N N D C R D R C T L R L VIRTUE FUEL COAL REDUCTION ACTUAL MENTION DAUGHTER INSERT DECIDE CLEVER CEILING TEND WRAP 10 x 9 = IDENTICAL 1 cm = 10 mm 72,418 + 64,493 = 9 0 10 cm = mm - 6 9 word root meso can mean middle mesoderm edHelper Name: How many of these can you write about? Think! Write! Check all the ones you answered. Where is your favorite place to buy pizza? How long has this pizza place been open? Who are the owners? Tell the story of your favorite pizzeria. Create a new pizza for the local pizzeria. Describe your new pizza. Name the pizza. Create an advertisement for your new creation. Don't stop writing. Use a blank piece of paper to continue. Name: edHelper The Campaign for the 2008 Presidential Election It was nearly two years until the election, but already the wheels were in motion to start the process of electing the next President of the United States. Since the current sitting president, George Bush, had already served two terms, he was not eligible to run again. His vice president, Dick Cheney, chose not to run. This meant that it would be a wide open contest. No one had a clear advantage. Anyone could win. There were plenty of politicians who were interested in the job. Many names were suggested, and many hopeful candidates considered their prospects. Soon the Democratic Party had a large field of candidates, many of them current U.S. senators. There was Joe Biden, Hillary Clinton, Chris Dodd, John Edwards, Dennis Kucinich, Barack Obama, and Bill Richardson. The Republican Party had many candidates, too, including Mike Huckabee, Rudy Giuliani, John McCain, Duncan Hunter, Ron Paul, Mitt Romney, Tom Tancredo, Fred Thompson, and Tommy Thompson. Smaller parties, like the Green Party, fielded their own candidates. Ralph Nader, who had run in several earlier presidential elections, chose to run as an Independent. Some other names were frequently suggested as possibilities including civil rights leader Al Sharpton and former vice president Al Gore, who had become popular for his environmental activism, but neither of these men chose to enter the race. The candidates who did decide to enter the race had to work fast. They needed to gain as much popular support as they could and as fast as they could. They needed to mobilize volunteers and paid campaign workers and organize their campaigns. They also needed to raise money-- lots of money. Some candidates started out with a slight advantage. New York Mayor Rudy Giuliani, a popular figure ever since 9/11, was an early favorite.