The Critical Zone

Weathering, Erosion, and Deposition


Weathering describes the chemical and physical decomposition of rocks and minerals through contact with our atmosphere. Rocks and minerals subject to weathering are not moved during decomposition. In contrast, erosion involves the entrainment and transport of rock and mineral particles by wind, water, ice, and gravity; a reduction in velocity of the transport medium or increase in resistance of the transported particles results in deposition or the addition of material to the landscape. Note that biota (i.e., biogeomorphology) can play an important role in both weathering and erosion.

Reading assignment

To learn more about the processes of weathering, erosion, and deposition, please visit and read the following:

In addition, read:

  • "Physical and chemical controls on the critical zone" by Anderson et al. (2007)

which is located in Library Reserves, so that you can develop a more evolved view of the relationship between these processes and the concept of the Critical Zone as a "feed-through reactor."

You will be asked some questions related to these readings in the following activity.


For this activity, I want you to complete the two-page report you began on page 4 of this lesson.


  1. Open the document you began on page 4.
  2. As you read through the materials listed above, recall our lesson on soils and consider the role these processes have in shaping the Critical Zone. Soils consist of unconsolidated material subjected to physical and chemical weathering.
    • Do you think all soil parent materials were subject to erosion and deposition?
    • Are some soils the result of weathering of bedrock in place, that is not subjected to erosion and deposition?
    • If so, how do soils developed directly from bedrock differ from soils developed on unconsolidated material, if at all?
  3. Re-save your document.

Submitting your work

Upload your report to the "Lesson 8 - Geology" dropbox in Canvas (see the Modules tab) by the due date indicated on our Canvas calendar.

Grading Criteria

You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.