Work began work in earnest on the mural we are making to illustrate the timeline of Earth's history as geologists have come to understand it. We will continue our work tomorrow as students illustrate the timeline for each period of time that we marked off today.
Homework:
Students worked in pairs to identify significant features of each geological period, era, and eon.
Assignment:
How do we know the ages of the rocks in which we find evidence of past life on Earth? One important tool for this is radioactive dating. So we introduced radioactivity today. We will be making a timeline for the hallway, an 11-meter-long sequence of Earth's history. Students will also be making travel brochures for each of the 11 geologic periods of the Phanerozoic era. More details about this will be noted next week.
We presented information about the Hadean and Archean eons, including evidence that there were blue-green algae even in the Hadean Eon. The variety of life on Earth grew through the Archean Eon and the following Proterozoic Eon. Then we enter the Phanerozoic Eon, the one we are now living in. It's beginning is marked by the Cambrian Explosion. Life became abundant, and in short order, geologically speaking.
We figured out a bit more clearly how to translate years into distances for our Timeline For Planet Earth project. The Hadean and Archean Eons were front and center today. Fossil bacteria point to the emergence of life on Earth somewhere around the beginning of the Archean eon, 4 Gya.
Assignment:
The early development of planet Earth, especially the impact with Theia, a Mars-sized planet that hit Earth about 4.5 Gya, was the main focus today.
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Earth ScienceMr. Swackhamer Archives
March 2020
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