In the last lesson, you were introduced to the concept of the Critical Zone as a feed-through reactor (Anderson et al., 2007). As we move forward in this unit, I first want you to consider the relationship between the feed-through reactor and isostasy [1]. Imagine a mountainous setting in which active erosion constantly removes weathered material from the summits: the unloading of weathered material allows the underlying crust to readjust by uplift, thereby physically raising unweathered rock rapidly into the feed-through reactor. Eventually, the landscape may mature to one with low topography and little relief as the deep crustal root has been exposed, weathered, and brought toward isostatic equilibrium with the underlying mantle. Thick soil profiles develop and blanket underlying unweathered rock, slowing the rate at which the unweathered rock is processed through the reactor. Furthermore, recall from Lesson 2 (reading Brady and Weil, pp. 41–2 and 61–2) that topography is the configuration of the land surface described in terms of elevation, slope, and landscape position differences, and that topography can hasten or retard the effects of climate on parent material-weathering by creating a balance between erosion and pedogenesis.
Because topography often reflects the distribution of different parent materials in many landscapes, detailed soil maps can be useful for interpreting geology, and geological maps can in places be made directly from soil maps [Birkeland, P. W. (1999). Soils and Geomorphology (3rd ed.). New York: Oxford University Press, p. 31]. Mappable soil bodies typically display patterns of distribution based on underlying bedrock and landforms—to fully understand soils one must make an in-depth assessment of geomorphic settings (Birkeland, p. 49, p. 1).
Having considered the variables associated with bedrock type, the rock cycle, tectonic setting, weathering and erosion in the last lesson, now we will explore geomorphic environments and the processes that can move and shape them to learn about the links between landforms, soils, and the Critical Zone. I'll remind you here, as I did in Lesson 2, to consider the outstanding question in Critical Zone science learned in a Lesson 1 reading (Brantley et al., p. 11): Can a unified approach be developed to characterize environmental conditions and mechanisms that produce different soil types?
By the end of this lesson you should be able to:
Lesson 9 will take us one week to complete. As you work your way through these online materials for Lesson 9, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 9. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Report (1 page) on topography and feed-through reactor at your study site | page 2 | Post to the Lesson 9 - Catena dropbox in Canvas |
Respond to question on aerial photo availability in your state Report (1 page) on aerial photo analysis |
page 8 |
Email directly to Tim Post to the Lesson 9 - Aerial Photo dropbox in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
A remarkable aspect of Earth's surface is the seemingly infinite variety of landforms. However, some landforms possess certain characteristics that differentiate them from other landforms, a fact that is fundamental to geomorphology [2], the field-oriented study of landforms at the interface between geology and many other disciplines working to understand surface processes. The applications of geomorphic knowledge can range from engineering projects dealing with the physical properties of landforms to geological studies of the record of past climate change recorded by landforms. It is this overall lack of rigid philosophical boundaries that may be geomorphology's greatest attribute—interdisciplinarity (Ritter, D. et al., 2002, Process Geomorphology, 4th edition, p. 1–2).
Diversity in the Critical Zone is displayed by the distribution of soils across landforms, reflecting variable chemical and mechanical weathering processes as well as physical erosion and chemical denudation. These processes, in turn, control the internal structure of the Critical Zone, the feed-through reactor of Anderson et al. (2007), through which changes in surface area, flow paths, and material residence time impact element and nutrient weathering fluxes.
In succeeding sections 3 through 7 we will explore five classes of geomorphic environments and the processes that occur with them. Before we launch into this more detailed study, I want you to more fully understand basic concepts of topography, including the influence of slope orientation or aspect on pedogenesis, by completing the following activity.
L9_catena _AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L9_catena _eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your paper to the "Lesson 9 - Catena" dropbox in Canvas (see the Modules tab) by the due date indicated on our Canvas calendar.
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.
Complete the following reading assignments:
Wind can be an effective geomorphic agent. Obviously, the presence of regular and/or strong wind is required for a specific landscape to be dominated by wind erosion and deposition, but various physical properties are also important. For example, regions showing a paucity of vegetation or preponderance of unconsolidated sediment are more susceptible to wind erosion.
Complete the following reading assignments:
In an activity in Lesson 4, you learned about the formation of glaciers and the role and effect of glaciers on climate. Now we turn our attention to some of the most spectacular landscapes on Earth—the result of glacial erosion and deposition. Understanding glacial motion, recorded in glacial landforms, is fundamental to current considerations of ice sheet meltback, sea level rise, and global climate change.
Complete the following reading assignments:
Remember my visit to Bear Meadows in Lesson 3? You might want to re-watch that video to refresh your memory . . .
Glacial geomorphology has proven quite useful to planetary geologists interested in understanding the evolution and history of the surface of nearby planets in our solar system. Visit the following hyperlink for a brief introduction to glacial geomorphology and Mars.
You may find the following resources useful in your classroom:
Unique landforms and patterns of drainage called karst or karst topography primarily form in temperate to tropical regions, though they are found in arid and polar regions too. The common feature shared by all karst landscapes is that they are underlain by chemical sedimentary rocks particularly susceptible to dissolution, carbonates and/or evaporites. The landforms result mostly from chemical weathering of the host rock and the progressive integration of subsurface cavities, though collapse into solution cavities can also be important. Karst landscapes are often dominated by underground drainage networks that interrupt and capture surface water flow.
For a relatively succinct definition of karst, from the Canadian perspective, follow this hyperlink:
Of the karst-forming rocks, the carbonates (dolostone and limestone) are much more abundant than evaporites (mostly deposits of gypsum and anhydrite), therefore karst landscapes are most often found in regions underlain by carbonate rocks. The following Web site will help you learn more about limestone karst, including information on the relationship between lithology, porosity, permeability and karstification, the distribution of karst lands in the United States, the driving mechanics of karst processes, and links between surface water flow, aquifers, and groundwater.
To learn about the distribution of karst landforms in central Pennsylvania, the relationship to lithology, and groundwater flow, watch the following video of my visit to Tussey Sink.
Some basics of karst processes and landscapes focused on caves are presented at Teachers' Domain as "I [15]ntroduction to Caves and Karst." [16]
Nearshore coastal environments host most of humanity, at the interface between the vast oceans that cover 70% of Earth and the continents, home to all our soil and the Critical Zone. The oceans possess energy that is transferred to and manipulates land through erosion and deposition. Humanity's land use has greatly strained coastal environments; therefore, a thorough understanding of coastal processes betters our chances of sustaining life and human endeavors in this very dynamic environment. Be aware that these concepts apply to shore lines along large lakes, too!
To learn about shoreline processes and coastal evolution, wave refraction and erosion, sediment transport and deposition, and submergent and emergent coastlines through a series of schematic diagrams, follow this hyperlink:
More information on classification, with nice imagery, can be studied at:
The following two hyperlinks lead to other reviews of coastal processes and landforms, as well as wave refraction, erosion, and deposition, importantly with nice images:
To view a slide show covering coastal erosion, corrasion and corrosion, subaerial procesess, and coastal classification, including nice images of headlands and bays, wavecut notches and platforms, cliffs, sea caves, and arches, and the stages of coastal development, see:
While field studies are essential for understanding the geomorphic environment or setting of a region, remote sensing imagery—specifically easily obtained aerial photographs and satellite imagery—provides a broad overhead view, a context in which to place field observations. For this reason, in this section of the landform lesson, we will explore various online resources that provide overhead imagery. Before you begin the following activity, go to Fluvial/Deltaic/Coastal Landforms [22] and Karst/Lacustrine/Aeolian/Glacial Landforms [23] to view aerial photographs representative of the major geomorphic environments presented in sections 3 through 7 of this lesson.
L9_remotesensing_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L9_remotesensing_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your report to the "Lesson 9 - Remote Sensing Report" dropbox in Canvas (in the lesson under the Modules tab) by the due date indicated on our Canvas calendar.
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.
Go to the NASA website and view the learning module Blue Marble Matches [31] - you may find it to be something to introduce into your classroom!
In this unit, we have focused our attention on the lithosphere and explored a number of aspects of geology and geomorphology, mostly focused on parent material and topography factors in soil formation. It should be clear to you that Earth's surface is covered by landscape elements that can be classified according to processes and landforms unique to those processes. You should also know that while geomorphology and geology are field-oriented sciences, the study of remotely sensed imagery can greatly enhance our understanding of a landscape and the processes that formed it. Considering the resources you've been introduced to in this lesson, you should also now know how to obtain such imagery for your own use.
You have finished Lesson 9. Double-check the list of requirements on the Lesson 9 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
Links
[1] http://en.wikipedia.org/wiki/Isostasy
[2] http://en.wikipedia.org/wiki/Geomorphology
[3] http://en.wikipedia.org/wiki/Fluvial
[4] https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870008706.pdf
[5] http://www.physicalgeography.net/fundamentals/10z.html
[6] http://www.physicalgeography.net/fundamentals/10ah.html
[7] http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA244855&Location=U2&doc=GetTRDoc.pdf
[8] http://www.earthonlinemedia.com/ebooks/tpe_3e/glacial_systems/outline.html
[9] http://www.revisionworld.co.uk/a2-us-grades-11-12/geography/glacial-environments/glacial-processes-landforms
[10] https://editors.eol.org/eoearth/wiki/Periglacial_processes_and_landforms
[11] https://en.wikipedia.org/wiki/Glaciers_on_Mars
[12] http://www.elcamino.edu/faculty/mreed/physical/101%20Powerpoint/glaciers.ppt
[13] http://www.thecanadianencyclopedia.ca/en/article/karst-landform/
[14] http://www4.uwsp.edu/geo/faculty/lemke/geomorphology/lectures/07_karst.html
[15] http://www.teachersdomain.org/ext/ess05_int_caveintro/index.htm
[16] http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.caveintro/caves-and-karst/
[17] http://www.tulane.edu/%7Egeol113/COASTAL-PROCESSES-1a.htm
[18] http://geobytesgcse.blogspot.com/2007/08/coastal-erosion-landforms-features-and.html
[19] http://www.physicalgeography.net/fundamentals/10ac.html
[20] http://www.physicalgeography.net/fundamentals/10ac_2.html
[21] http://www.scribd.com/doc/305249/Coastal-Erosion-Processes-and-Landforms
[22] http://priede.bf.lu.lv/GIS/.Descriptions/RST/Sect17/nicktutor_17-4.shtml
[23] http://geoinfo.amu.edu.pl/wpk/rst/rst/Sect17/Sect17_5.html
[24] http://eros.usgs.gov/
[25] http://landsatlook.usgs.gov/
[26] http://fermi.jhuapl.edu/states/states.html
[27] http://www.flashearth.com/
[28] http://www.ssec.wisc.edu/sose/pirs_activity.html
[29] https://www.pasda.psu.edu/
[30] http://www.terraserver.com/
[31] http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/Blue_Marble_Matches.html