Week 11: Earth's Structure

 Lab: 
First, we discussed the law of superposition. This law states that the deeper layers of rock in or outside of the earth are the oldest, and as they get closer to the surface, they are younger. We then determined the order in which different formations occurred based on the principle of superposition using a handout. We found that if there are rivers or other movements (earthquakes, etc) then that movement must have occurred before material filled it in. 

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Sand Sample Classifications: 
    1: Beach Sand (Ocean) -- Bigger pieces with irregular shapes

    2. Dune -- fine, opaque 

    3: Beach (Ocean) -- Huge pieces irregular in size, pitted, dark in color 

    4. Beach (Ocean) -- Very irregular in size, random bits, rough, not polished 

    5. River -- Polished, smooth, similar in size 

    6. Dune -- very fine, frosted, similar in size, slightly pitted

    7. River -- polished/smooth, similar in size 

    8. Dune -- Very fine. pitter, similar in size and shape

    9. Beach -- irregular in shape and color, mixture of polished and rough/opaque

    10: Beach -- irregular mixture, very large pieces, rough

    11:River -- very polished, egg-like, similar in color and shape

We explored the first five samples, knowing where they were from, and taking note of their characteristics. We then explored the other six samples, using the evidence from the first five to take informed guesses about where they might be from. Classifying these samples is similar to how scientists use data already collected to inform the new explorations that they make.

Lecture:

This week's lecture discussed the principle of water displacement and buoyancy using the Archimedes principle. It was cool to see that something could look gold but not be pure gold. We used the Archimedes principle to describe and explore specific gravity, and used specific gravity to determine if various geodes were hollow. I had never heard of specific gravity before, especially not with geodes so this was a fun experience! I even got to crack open the geodes!

Pressbook Reading:

- The Law of Original Horizontality states that successive layers of rock are formed in flat, horizontal layers because gravity pulls on the rock when it forms. Because of this and the law of superposition scientists are able to more accurately determine the relative age of layers of rock. 

- Fossils and the law of superposition are closely related as fossils are found within layers of rock formations. They can then determine the relative age of the fossil based on the age of that rock layer. 

- Sand that is weathered by wind is scratched or frosted and generally more uniform in size whil esand weathered by water is much more polished, smooth, and rounded.