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Model Geologic Time

6-10th Grade Science - Earth Science

Content Topics

  • Geologic Time and Processes

Duration Two class periods (approximately 2 hours)

Objective: 

Students will create a model where they understand how sediment layers are transported and then placed down over time. They will create their own story about this based on information about where the sediments originated. During this time, different geoscience processes will affect where they are laid down, and how long they stay there. Then, students will recognize how different rock layers represent different amounts of time and different geological processes. One geologic structure will be compared to another where the fossils within the layers will be analyzed to understand how oceanic and continental conditions can change over time.

Guiding Questions: 

  • How is geologic time recorded?
  • Can you model the geologic time scale?
  • How does one change to Earth’s surface affect other processes?

Education Standards:

  • MS-ESS1-4. NGSS Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth’s 4.6 billion-year-old history
  • MS-ESS2-2 Construct an explanation based on evidence for how geoscience processes have changed Earth’s surface at varying time scales and spatial scales
  • MS-ESS2-3 Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions
  • HS-ESS2-1 Develop a model to illustrate how Earth's internal and surface processes operate at different spatial and time scales to form continental and ocean-floor features
  • HS-ESS2-2 Analyze geoscience data to make the claim that one change to Earth's surface can create feedbacks that cause changes to other earth systems
  • HS-ESS2-4 Use a model to describe how variations in the flow of energy into and out of Earth's systems result in changes in climate
  • HS-PS3-2 Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles and energy associated with the relative position of particles

Materials and Resources:

  • Plastic tubs to place layers down
  • Informational clues about where the sediments originated, so students can recreate the wind/rivers/desert sands coming in
  • Actual sediments from the layers for students to use?
  • Fossil replicas from the layers to place within the layers
  • Information about layers removed from chosen geologic site and how they were transported away
  • Geologic formation clues from the past to present with fossils for layers. Real samples of the layers to look at
  • Samples of the actual fossils so students can predict their environments
  • Samples of igneous, sedimentary, and metamorphic rocks
  • Topographic maps of the regions’ rock layers which include your chosen geologic site and formation
  • Map/model of the prehistoric Montana during chosen time period

Local Resources:

Part 1 (Min)

Presentation:

Items will be presented throughout the activities. As students approach new pieces, they will fill in their answers on the assessment sheet and place labels on their models.

Activity:

Students will come up with their own story about where the sediments came from and how they ended up in the rock layers (erosion and deposition). They will lay the sediments down in the correct sequence with index fossils included in the layers. Next, students will create a scale model of the geologic time scale for their layers on a strip of cardstock that will be placed alongside the rock layers. They will place labels on the oldest layers and youngest layers. Students will calculate the energy at each level and place labels on the model. Then, they will calculate the velocity each would have at the bottom of the model and they will place the layer labels at their new distances on the ground away from the geologic time model.

Once we describe to the students the actual environment where sediments originated, we will discuss what an unconformity is and show them a picture of the rock strata of your chosen geologic site. Students will hypothesize what caused those layers to disappear and use the law of conservation of mass to discuss where those layers went depending on the energy source they came up with.  This will lead into a discussion about energy transformations. Based on the real information about where layers came from, they will place an energy transformation at each level on their geologic time scale. 

Finally, students will look at the local formation’s layers up to the Cretaceous level. They will look at real fossils and replicas and sediments from within the local formation’s layers to describe what the environment was probably like. They will hypothesize what kinds of weather events could lead to this environment and then we will describe the prehistoric environment. After this, students will discuss how environments change over time and what the thermal and kinetic energy looks like in those different environments at different times.  They will also describe how feedback mechanisms from one change on Earth’s surface can lead to further changes on Earth’s surface.

Assessment

Students will use the law of superposition to understand which layers are the oldest and youngest and label them. They will record their predictions about the environments in the worksheet after they view information about sediment environments and look at the fossils from within the layers. 

Students will discuss all of the energy transformations that occurred in the environments. They will record these predictions in the worksheet. Then, they will determine how much PE each layer has based on 2 kg of mass. They will use KE = 1/2mv2 to determine the velocity of the particles at the bottom of the hill and which sediments will travel the furthest if they roll downhill.  These pieces will be placed on the model and recorded on the data sheet. 

Students will record their hypotheses about the local formation and the environmental/weather changes that occurred during this time. Then students will include their discussions about thermal and kinetic energy changes over time and how these changes lead to changes in Earth’s surface over time and affect each other.