Lesson 3 Date: LT: I can use a model to describe how earth materials are sorted by wind. Sponge: Which type of rock is smooth, made of clay, and doesn’t fizz?

TO do…

Pre Lab discussion We agreed in the last lesson that the Grand Canyon, and Earth’s entire surface for that matter, is made of rock. We also agreed that learning about the rocks of the Grand Canyon prompted us to think of several new questions. For the rest of the unit, we are going to be investigating all of the processes that cause landforms like the Grand Canyon to form and change. We will start by investigating processes that happen on Earth’s surface. Since Earth’s surface is made of rock, let’s start by thinking about rocks. My question today is: How big are rocks?

Pre Lab discussion What do scientists call an object that we are using to represent something else for the purpose of studying and learning?

Pre Lab discussion What do scientists call an object that we are using to represent something else for the purpose of studying and learning? A model. A model is a representation of an object or a system. They are helpful for understanding things that might be too large, too small, too far away, too dangerous, too costly, too fast, or too slow to observe directly. Models give scientists an opportunity to explore objects, systems, and processes that they cannot easily observe in nature. In geology, models are very important because many Earth processes take hundreds or thousands of years to produce changes that we can observe.

Pre Lab discussion Find the picture of the Colorado Plateau in our textbook (page 127). The Colorado Plateau is composed of rock layers, as we saw in the Grand Canyon images in the last lesson. This basin is a model of just the top layer, the layer you would walk on if you visited the plateau. Each group will get…. one cupful of mixture, two paper plates, two sheets of newspaper, two hand lenses, two rulers You will use this to explore How big are rocks?

Your task…. Your task is to analyze a sample of the model plateau and sort its components into groups based on similarities. You should divide your sample between the two paper plates so that pairs of students can work together. You should put the newspaper sheets underneath the paper plates in order to ease cleanup efforts. Note: You do NOT have to sort your sample the same way as the folks across from you.

Lets do it the geologist way! Geologists separate rock mixtures into different sizes in order to describe the mixture more precisely. Your challenge is to organize these rocks into four size categories. You will have to decide what criteria to use to distinguish one size category from another. Fill in the chart in your notebook!

Wentworth Scale Note: You have a copy of this in the back of your notebook!

Discuss components Most of you included gravels, different sands, silt, and clay. Do rocks always appear in nature mixed up by size?

Discuss components Most of you included gravels, different sands, silt, and clay. Do rocks always appear in nature mixed up by size? No, sometimes they are alone. Other times they may be in a uniform group. Where in nature can you find sand?

Discuss components Most of you included gravels, different sands, silt, and clay. Do rocks always appear in nature mixed up by size? No, sometimes they are alone. Other times they may be in a uniform group. Where in nature can you find sand? Beach, riverbeds, desert, etc. How is sand separated from other sizes of earth materials in nature?

Discuss components Most of you included gravels, different sands, silt, and clay. Do rocks always appear in nature mixed up by size? No, sometimes they are alone. Other times they may be in a uniform group. Where in nature can you find sand? Beach, riverbeds, desert, etc. How is sand separated from other sizes of earth materials in nature? Wind and water One limitation of our plateau model is that it does not include water. So let’s just think about wind blowing across the plateau. Would wind separate materials in your riverbed model?

Discuss components Most of you included gravels, different sands, silt, and clay. Do rocks always appear in nature mixed up by size? No, sometimes they are alone. Other times they may be in a uniform group. Where in nature can you find sand? Beach, riverbeds, desert, etc. How is sand separated from other sizes of earth materials in nature? Wind and water One limitation of our plateau model is that it does not include water. So let’s just think about wind blowing across the plateau. Would wind separate materials in your riverbed model? Yes Which size of materials would be moved most easily by wind?

Discuss components Most of you included gravels, different sands, silt, and clay. Do rocks always appear in nature mixed up by size? No, sometimes they are alone. Other times they may be in a uniform group. Where in nature can you find sand? Beach, riverbeds, desert, etc. How is sand separated from other sizes of earth materials in nature? Wind and water One limitation of our plateau model is that it does not include water. So let’s just think about wind blowing across the plateau. Would wind separate materials in your riverbed model? Yes Which size of materials would be moved most easily by wind? Smaller, lighter particles would move most easily. Lets surround Table 1 and see if this is true. We will use our breath as wind!

Big ideas from today… Rocks are all different sizes, from the tiniest particle of clay to the largest boulder and everything in between. For example, within the plateau model there were larger pieces of gravel and tiny pieces of sand. Scientists use measurements and the Wentworth scale to classify different sizes of rocks.

1. In what ways is the model useful for thinking about the Colorado Plateau? The model is made of rocks of various sizes, everything isn’t exactly the same. Some of the rocks that make up the plateau can be moved by wind in this model like rocks can move across the plateau

2) What are some limitations (ways the model is not as useful) of the model? One limitation is that the plateau model does not include water, so it cannot be used to study how water moves the rocks. Another limitation is that it is not made of exactly the same rocks as the Colorado Plateau.

3) What is one change that could be made to the model to make it more useful? One change is that we could add water to the plateau model and see how that changes the rocks.