Week 11 - Rocks and the Rock Cycle

Lab

In lab we started by talking about the law of superposition... everyones fav! This law basically states that the older stuff is at the bottom and the longest is at the top. We used this to work to place different layers of rock in order from oldest to youngest based off different photos. Immediately, I was taken back to my ninth grade earth and space science class and I could remember doing exactly what we were doing in lab, but back in early high school... props to Ms. Howlett :) 

Then we moved into talking about different characteristics that sand from different places had. We looked closely at sand from beaches, dunes, and rivers around the world. Our group decided to look at each group and write down observations about each sample. All of the different rock types were from different areas and all had different colors, were different shapes, and just looked different. We came up with some characteristics for sand found in rivers, dunes, and beach's. 

River Sand Characteristics

• Very tiny rocks, multicolored, glossy/matte appearance - 7

• Bigger/smaller size rocks but bigger than the rocks in 7, multicolor - 5

• Lots of colors

• All of the rocks coming from upstream blending together - often an entire regions different sands mixed 

Dune Sand Characteristics

• Very tiny grains, all relatively the same color and size - 6

• Also very small grains, relatively the same colors - 2

• Smaller rocks and uniformed

• Bound by energy of the wind 

Beach Sand Characteristics

• Rocks have little tiny rocks within them - 1

• Rocks are shiny, almost translucent - not clear/see through but light in color - 3

• Rocks are the same color as each other, more different in sizes  - 4

• Multi-color and all relatively the same size - 8

• Hints of red, shiny, light in color, all relatively the same size, blue green color but appears black when all together - 9

• whole/broken shells in it, a variety of rock colors and sizes, matte looking- 10

• Seashells

11- pearly look, all white and gorgeous - oolite, perfectly rounded in verify shallow water that is temperate and they grow… there's layers inside of them - can find the same rocks in Muscatine - from Abu Dhabi

• Muscatine must've been an ocean at some point

• 80 degrees, shallow

Lecture

Geode(State rock of Iowa): A rock with crystals inside 

• Density in water can help find the volume

Density:

• Anything lower than 1=float and less dense than water 

• Anything more than 1= sink and more dense than water

• Less sugar means it’s less dense

Buoyancy - Archimedes Law and Geodes

	Rock 1:	Rock 2:
Weight in Air	143g	132.9 g
Weight in Water:	56.2g	58.7 g
Archimedes Law: Specific Gravity = W(air)/ (W(air) - W(water))	143 (143-59)= 1.7	132.9 (132.9-58.7) = 1.79

• If they’re less than 2.7 which is what quartz density is, it means that they are hollow

Textbook

What I learned: I learned that a geode forms when a rock gets a cavity, and this can happen in several different ways. One way a cavity could form is when carbon dioxide and water vapor form in flowing lava. As this molten rock is cooling down, the gas is dissolving leaving an empty space behind. Another way is when the lava hardens under water, resulting in the outside layer cooling faster and becoming more brittle.

What I found most helpful: I found the video describing Archimedes' principle to be the most helpful in my reading. When I read the text describing the way this principle worked and skipped down to the formula, I was overwhelmed. The video broke it down in a student friendly way and use illustrations to help with the break down. 

Question(s): Why does sand sometimes appear to be a different color that it actually is?