Week 11: Erosion

Learning in Lab:

This week in lab we discovered more about weathering and erosion through a sand experiment. We started by talking about the Law of Superposition and how scientists tell which fossils or rocks have been there the longest. The Law of Superposition says that sedimentary rocks form layers that become buried under more layers over time, and the layers towards the top are younger than the layers below. Then, we moved onto our discover of sand and determining how they were made through water, wind, or glaciers. Sand created through water is polished, smooth, and generally similar in size. Sand created through glaciers is polished, smooth, and irregular in size. Lastly, sand created through wind is opaque, frosted, pitted, and very finely grained. Through our investigation, we found that a majority of the sand that we observed came from water, and only 1 was created by wind, and 1 was created by a glacier. I thought it was interesting to look at the different sand types under the microscope and see how my initial thoughts differ from the actual answers. 

Law of Superposition

Learning in Lecture:

During lecture this week we did an in-class experiment regarding buoyancy and water displacement. We started by predicting wether different sodas would float or sink in water. The results were based on if the soda was less or more dense than the water. The only can that floated was diet coke since it has no sugar in it. Then, we looked at two different ways we can incorporate literacy into science education. For the upper elementary students, we could read Archimedes Principle that talks about how he questioned if his crown was pure gold or not. His discovery came when he was taking a bath and the water was displaced. Since gold is more dense than water, there will be a larger displacement, silver is less dense, so it will displace less water. The other book was Mr. Archimedes bath and it was a children's picture book that described similar ideas of water displacement. We took our learning from the book and tested it using Archimedes Law (W(air)/ W(air)-W(water)) to determine if a geode was hallow or not. We found that in the air, the geode weighs 82.5g and in the water it weighs 41.8g, Archimedes Law of specific gravity gives us an answer of 2.027. Compared to the density number of 2.7, we can determine that the geode is more than 50% hollow. 

Sand Lab

Textbook Connections:

1. What did you learn?

The three types of rocks are igneous, sedimentary, and metamorphic. Igneous is formed when magma cools and was the first type of rock on Earth, sedimentary is formed when many small particles are compacted together over time, and metamorphic rocks are formed when existing rocks undergo extreme heat and pressure. Igneous rocks can be intrusive or extrusive, intrusive rocks are inside of the earth and form large crystals. Extrusive rocks are outside of the earth and form smaller crystals. Geodes are formed when a cavity occurs inside of a rock such as a bubble of CO2 and water vapor during flowing lava, or when lava solidifies underwater. The geodes found in Iowa are cavities that form in sedimentary rocks. If a geode is less dense (found using Archimedes Principle) there will be more crystals inside because it is more hallow. There are two types of weathering: mechanical which breaks down the rock into smaller fragments, and chemical which physically changes the rocks composition. Sand, for example, is created when rocks are weathered or broken town by water or wind. 

2. What was most helpful?

I appreciated the diagram of the rock cycle and how it showed how each rock can be formed in different ways through the various processes. The table was also beneficial to highlight key processes of how the rocks can be differentiated. 

3. What do you need more information on?

I would like more information on how geodes are formed. The pressbook slightly touched on it but I think that a video or diagram over time would be helpful to best understand how the cavities in rocks are formed. 

4. What questions, concerns, or comments to do you have? 

I liked the different version of water displacement and how it is more accurate than simply seeing how much of the water rose in a container. 

Sand from Water