This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.
Ideas for teaching about the early atmosphere
These teaching ideas were submitted during the April 2007 workshop on Teaching About the Early Earth. They represent collaborative brainstorming rather than finished products, but they are a useful starting point when seeking ideas for your classroom.
Understanding Faint Young Sun ProblemSubmitted by Cindy Shellito, James Kasting, Dave Mogk, Huiming Bao, Susan Childers, Staci Loewy, Darrell Henry
Questions:How did Earth remain habitable despite the faint young sun?
Introduce radiative balance—effects of albedo, luminosity, greenhouse gases and associated feedbacks and forcings.
Activity Ideas:Intro level classes
- Goal: Get students to think broadly about types of forcings that are operating on climate.
- Ask students to brainstorm possible drivers for maintaining or changing climate.
- What could force us out of that state? What could bring us back?
- Daisyworld or Stella model—demonstrate feedbacks
- Compare other planetary atmospheres
- Have Carbonate-silicate cycle—solid earth is buffer and contributer to fluid earth system—discuss feedbacks on climate cycle.
- Compare heat flow in the atmosphere (radiative effects of greenhouse gases) to figure out the indirect effects of geothermal heat flow.
Follow-up Discussion Question:What are some the sources of these greenhouse gases?
Would the Earth be habitable if there wasn't life on it?
Possible Field activity:Field trip to a swampy area to measure methane emissions.
ResourcesAmerican Museum of Natural History
Daisyworld/STELLA/ NASA 'GEEBITT' models (GEEBITT activity example)
Two Starting Point activities have been created using Daisyworld:
When did atmospheric oxygen rise to biologically and geologically significant levels?submitted by Carol Frost, Joe Reese, Mark Skidmore, Kyanna Czek, Mark Leckie, Stan Awramik
Question1. When did atmospheric oxygen contents rise to geological and biologically significant levels (something around 15% PAL)?
Goals:Think globally, understand tools used to reconstruct atmospheric composition, evaluate evidence
Intro. Organisms have evolved to use oxygen. When did this become possible?
1. Study geologic evidence: detrital pyrite, uraninites, redbeds (Holland 1994 summary chart), BIF (include paleosols for more geochemically sophisticated class)
Look at mineral assemblages, surficial depositional environments, and identify what these rocks indicate about the atmosphere composition at the time they were deposited.
2. Present stable isotopic data: S in sedimentary materials, [C isotopes (2 non-marine anomalies at 2.7 Ga) for more advanced students]. What do these argue about atmospheric composition
3. Project involving key papers, including ones authored by:
- Elements issue on evolution of atmosphere
- GSA Today Archean-Proterozoic transition article (Emergence of an aerobic biosphere during the Archean-Proterozoic transition: Challenges of future research )
Class discussion to build a time-line. Have students identify the disagreements and outstanding questions.
Product:Each student writes 2-page position paper.
What is the evidence for the timing and rise in the concentration of oxygen in the earth's early atmosphere?Submitted by John Zawiskie, Megan Jones, Soichi Kiokawi, Bosljka Glumac
I Engagement:Class discussion with activities based on previous knowledge of how the transport of detrital grains affects their shape (tumbling experiments) and the results of chemical weathering of iron bearing silicates in an atmosphere with free oxygen such as red hematite layers in soil horizons.
II ExplorationStudent teams explore a time stratigraphic sequence of rock specimens from the Archaean to Early Proterozoic of the Huronian and Superior province of Canada and Michigan including: detrital pyrite and uraninite; red beds; Lake Superior BIF's and stromatolites.
III Student hypothesesStudent teams assess the nature of Archaean to early Proterozoic weathering and rocks to infer the presence or absence of free oxygen based on the fabric and composition of the rocks.
IV ElaborationSketch the stromatolite structures and ask them to research on-line as a source for free oxygen.
Atmosphere Brainstorming IdeasSubmitted by Linda Sohl, Joseph Hill, Bruce Oldfield, Mike Phillips, Becky Teed, Mike Williams, Julie Baldwin
Question 1.What does uniformitarianism really mean in Earth history?
Course:Historical geology, physical geology
Activities:- Think of a process going on today, and then identify how that might have been happening at a different rate, etc. in the past.
- Think of processes that are definitely not uniformitarian (occurred in the past but don't occur now).
Question 2.What are the causes of glaciation?
Course:Historical geology, climate change, physical geology
Activities:- Jigsaw exercise in assessing role of Milankovitch cyclity, carbon dioxide, methane, solar luminosity, albedo (volcanic dust), paleogeography, tectonics, ocean circulation
- Jigsaw exercise in constructing positive and negative feedback loops in climate; can you create a glaciation through the processes you identify?
- Perform/analyze climate simulations using output from EdGCM (http://www.edgcm.columbia.edu)
- Presentation for evaluation
- Was uniformitarianism a useful concept for your jigsaw projects?
Question 3.How does the level of oxygen change over time?
Course:Historical geology, climate change, physical geology
Activities:- Consider the differing arguments for when oxygen may have increased, and how?
- Plot changes in BIFs, uraninite, sulfur isotopes over time—what do they mean?
- What happens to oxygen levels if photosynthesis stops? How long would it take to go back to an anaerobic earth? (Use Biosphere 2 as a case study for an unexpected O2 sink.)
- How do you terraform a planet? What sphere (bio, atmo, geo, hydro) would you choose as most important?
Climate change in the Archean and ProterozoicSubmitted by Alisa Hylton, Bob Bauer, Joel Thompson, Aaron Cavosie, Paul Mueller, Wally Borowski, Alberto Patino-Douce
QuestionsWhat was earliest atmosphere and how did it evolve to 4.2 Ga? (CO2- rich or more reducing?)
What does the Precambrian rock record tell us about the evolution of the atmosphere/hydrosphere systems and climate change?
What is a modern planetary analog to snow ball Earth?
1. Selection of rock samples, images and strat column. Make sure students understand the significance of color and atmosphere using analogy of oxidized sediments.
2. Predict what would happen if free access to Oxygen. A thought experiment. Perhaps a demo of BIF in a bottle Fe2O3 scum.
3. Condense O2 with a narrow tube held in a container of liquid nitrogen.
4. How do we evaluate a system with no database; a trial approach where no database is circumstantial evidence.
5. You owe your car to Precambrian climate change.
GoalsStudents understanding data analysis vs modeling.
Students understanding that things change through time.
Students need a Precambrian perspective on climate change and differences in scale of change. This requires understanding magnitude of geologic time.