Earth Sciences, Inquiry and Design
3.5.7 A,B; 3.5.4 A,B
For this activity students will:
- Be able to explain how coal is formed.
- Observe how mountain building changed the shape of the coal seams and the qualities of the coal.
- Describe the settings of bituminous and anthracite coal.
Groups will present and explain their folded models.
Science and Technology
- Clay models from lesson #4
- Digital Shaded-Relief Map (DSR Map)
- PaGS Map 11 - “Distribution of Pennsylvania Coals”
- Coal in Pennsylvania, Educational Series 7 booklet
- PaGS Map 13 – Physiographic Provinces of Pennsylvania
- Plastic knives with smooth edges
- Whole class
- To prepare for this lesson, the teacher may want to create a chart of information about coal:
- soft coal
- burns hot
- typically found in unfolded rocks
- had a shallower burial (1-3 miles of sediments)
- hard coal
- burns hot but slower and longer; harder to ignite
- found in folded rocks, was more deeply buried (by 4-5½ miles of sediments)
- In this lesson students will learn/review the formation of coal. They will use their clay models to learn the difference between the typical settings of bituminous and anthracite coal. The students will discover that the topography can suggest what kind of coal can be found underground. That is, in general, bituminous is found where the crust has not been folded and anthracite is found where the crust has been folded. This reflects the mountain building forces, which first deeply buried the plants and then folded the rocks in eastern Pennsylvania. In western Pennsylvania, the plants were farther away from the mountain building and were not buried as deeply, nor were the rocks pushed and folded as much.
- Bring the groups together with their clay models from Lesson 4. Explain to the students they will be cutting their models in half.
Demonstrate for the students by cutting the teacher’s model (which has no folding). Have them cut their clay model in HALF. (ON PURPOSE – do not instruct them on which way to cut the model. HOPEFULLY some of the groups will cut their model across the ridges and others will cut with the ridges.) Have the students compare the exposed cross-section (flat layer exposed by the cut) of each model with the teacher’s model.
Explain using 1/2 of the unfolded model, that one of the layers is the coal laid down during the Pennsylvanian Period. Erosion of mountains laid layers of sediment down on top of the dead plants, squashing them until they became coal. Because the mountain building was toward the east, more sediment coming off the mountains deeply buried the plants in eastern Pennsylvania. Mountain-building forces also folded the rocks more in eastern Pennsylvania. To the west, the plants were less deeply buried.
- Slowly fold the teacher’s model and show how the folding distorts (thinning and thickening) the rocks. Explain that as the sediments deeply bury the plants, coal forms and loses impurities, becoming harder and shinier, as the heat from the deep burial “cooks” the coal. The heat drives off the moisture like baking a cake. Refer to types of coal on the chart.
Have the students return to their groups to decide which color will represent the seam of coal and talk about what happened to the coal.
Assemble the students and have each team present their model and tell which seam is the coal and how it changed during the deep burial and folding. Explain to the students that the deeply buried, folded coal is hard anthracite coal and the unfolded, less deeply buried coal (demonstrate with the unfolded half of the teacher’s model) is the softer bituminous coal.
Refer to the Digital Shaded-Relief Map (placed so all can see it). Using another map with the county names on it, have a student find Luzerne County on the Digital Shaded-Relief Map. Ask the students to predict if they would find anthracite or bituminous coal there. Have a student find Allegheny County. Ask the students to predict if they would find anthracite or bituminous coal there.
Use the transparency of the Distribution of Pennsylvania Coals map (PaGS Map 11) to verify that physiographic features allow you to predict where you will find the different kinds of coal.
Referring to the folded and unfolded models, discuss which coal would be easier to mine.
REVIEW: Discuss how anthracite is found in the eastern areas and the bituminous in the western regions of Pennsylvania.