Chemical Weathering

Kira Lawrence
,
Lafayette College
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Summary

This field trip assignment brings students to a local cemetery to collect data related to the age and extent of weathering of limestone and igneous tombstones. Students then analyze the data they collect using Microsoft Excel and use their results to answer questions about chemical weathering. This activity gives the students a chance participate in the process of scientific inquiry starting with data collection and finishing with interpretation of the data they have collected.

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Context

Audience

I use this lab activity in an undergraduate introductory geology course designed primarily for students who are not science majors.

Skills and concepts that students must have mastered

Students must be able to identify limestone versus igneous rocks. Students should have attended lectures on the process of chemical weathering.

How the activity is situated in the course

This is a stand-alone lab exercise.

Goals

Content/concepts goals for this activity

Concept goal: provide students with a tangible understanding of chemical weathering and differences in chemical weathering rates between different lithologies.

Higher order thinking skills goals for this activity

  • Process of scientific inquiry:
    • collect data,
    • analyze data,
    • interpret data.
  • Relate observations in their physical environment to concepts they are learning in class.

Other skills goals for this activity

  • working in groups
  • field work/data collection
  • analysis using Microsoft Excel - entering data, using formulas, generating and interpreting graphs

Description of the activity/assignment

This tombstone weathering lab is designed to provide students with tangible understanding of chemical weathering and weathering rates. To prepare for this lab, students will have learned in previous labs to identify common minerals and rocks and will have attended lectures about the process of chemical weathering. During the first part of the lab we travel to the city cemetery to collect data on the age and extent of chemical weathering of tombstones that are made of limestone and igneous rocks. After collecting data for ~1 hour, we return to the computer lab where students use Microsoft Excel to analyze and interpret their data. Their task is to calculate a chemical weathering rate for limestone for our region and compare that rate to those from other regions. This activity gives students experience in the process of scientific inquiry: data collection, data analysis and data interpretation. Students develop Microsoft Excel skills: writing formulas, producing charts, understanding trendlines and R2 values.

Determining whether students have met the goals

The students need to answer concept based question related to their analysis. Their responses to these questions indicate their level of comprehension of the concepts and their ability to have learned the skills necessary to complete the lab.

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