Be the Block: Working the Geologic Block Diagram as an Inquiry Tool

Students often have difficulty transposing 2-dimensional information into 3-dimensional space. Using their strengths in 2-D fields (the sides and top of the block), students construct a 3-D object from 2-D knowledge and observations.

The activity is designed to represent a model of Earth science inquiry in which students interpolate and extrapolate, develop and test models through observation, and subsequently test the interpretations derived from those models.

There are several objectives that can be build around this activity, depending on instructors' interests and students' needs. These include applications in structural geology, history of geology, physical geology, and stratigraphy. Arranged taxonomically (lower order thinking skills to higher order thinking skills):

• Recognize basic geologic structures (knowledge)
• Distinguish between types of geologic structures (comprehension)
• Apply interpolation skills to project between data points to patterns (application)
• Use surface and subsurface data to construct surface and cross-sectional representations (application)
• Use Steno's Laws (superposition, original horizontality, lateral extent)to develop 2-D and 3-D understandings. (analysis)
• Build 3-D projections from two sets of 2-D information (synthesis)
• Develop history based on type of rocks, types of fossils, presence or absence of fossils (evaluation)

This activity is used to illustrate both historical and methodological positions in the study of the Earth, stressing the importance of dealing with incomplete information, detailed descriptions through observation, and testing models and interpretations in light of new or potentially conflicting information.

Local relevance is very easy to inject into this type of activity, enhancing information on local and regional geologic history that might be presented in class. For example, in Shenandoah Valley one would observe synclines and anticlines, often with plunging orientations to the northeast. The block represent in this activity description is thus not unusual for the area. There are some high-angle faults, and a few hydrothermal veins. Further west, in the Valley and Ridge, there are more synclines forming ridge tops, ending with near high-angle, vertical (and nearly overturned) anticline ridges. In the Blue Ridge, there are overturned folds and thrust faults, in Proterozoic crystalline rocks and Cambrian age sediments.

Please see this link for the historical narrative that can be tied to: csmres.jmu.edu/geollab/vageol/vahist/L-TrJr.html

Other links of interest:

The Kentucky Geologic Survey has provided a look beneath the surface at the state of Kentucky, starting with fence diagrams to build understandings of block diagrams. http://www.uky.edu/KGS/geoky/beneath.htm

This fantastic site provides a series of QuickTime VR images of block diagrams, providing both general examples as well as specific examples from the Southwestern US. These diagrams are interactive and allow for manipulation, rotation, and erosion. http://reynolds.asu.edu/virtual_reality.htm

Related powerpoint presentation (PowerPoint 6.2MB Apr13 07). Not all of the images have been fully credited at this point.

An additional resource is a chapter on inquiry in Earth science, to appear in a pending NSF publication. The version attached is a slightly longer version than will appear in the volume.
Inquiry in the Earth Sciences (Acrobat (PDF) 286kB Apr13 07)

This activity does require a considerable amount of set-up time, no less than 30 minutes once the columns are established and the construction paper cut-out. At the simplest level, different colored construction paper rectangles can be used to represent different layers. Fossils, sedimentary structures, or specific lithologies can be added first when one has run out of different colors and needs an unambiguous distinction between different layers having the same color.

Please refer to the attached powerpoint presentation for the construction sequence for the blocks. Block Construction Sequence (PowerPoint 54kB Aug10 07)

1. Start with a standard foldable block diagram, assign colors to the various layers. If you have insufficient colors, add fossils or sedimentary structures reflective of relevant geology.
2. On a master copy, replace layers with data spaces. It is important to note that corners should have matching layers when folded, and the surface expression matches the corners, as well.
3. Using construction paper, secure columns about the room, using the orientation displayed on the block to guide where the columns are placed. It is important to maintain the appropriate orientation, with the uppermost layers towards the ceiling and the lowermost towards the floor.
4. It is also vital to maintain the appropriate front-to-back orientation, securing , surface expression data points on either the ceiling or on desks/tables.
5. Students collect data, recording the appropriate color and any fossils or structures in the blank spaces.
6. Students connect the data spaces with matching color lines on the sides and the top.
7. Students fold the block according to the directions and secure the corners

It would be useful to research local or regional geology to determine appropriate fossils or lithologies. In the Shenandoah Valley, for instance, common fossils include brachiopods, bryozoans, small trilobites, and perhaps some graptolites. Many of the rocks are shallow water limestones, shales, and deep water silica-rich carbonates Further west, into the Valley and Ridge, one would find some corals, brachiopods, worm tracks, perhaps some early plant fossils. Sediments are typically terrigenous, composed of stream deposits, conglomerates, sandstones, and shales. More advanced students and classes can used data on lithology and sedimentary structures to construct a geologic history for the area.

Assessment is embedded within the Learning Cycle itself, but summative assessment comes from synthesis writing tasks, requiring students to frame their understandings of this task with other historical representations in the Earth sciences.

Here is a rubric that could be used with the activity:

Yael Kali and Nir Orion, of the Weizmann Institute of Science, developed an instrument which provides a basic assessment of students' capacity to visualize 3-D or "penetrative" geologic structures represented in block diagrams. As such, it would make a useful pre-post test in conjunction with the block construction activity. See: 

Kali, Y., and Orion, N. (1995). Spatial abilities of high-school students in the perception of geologic structures. Journal of Research in Science Teaching, 33(4), 369-91.

http://www.design-principles.org/docs/GeoSAT/GeoSATNew1.0.doc
http://www.design-principles.org/docs/GeoSAT/GeoSAT_Code_Legend.doc

Depending on the particular instructional objectives, more objective questions about Steno's laws, possibly history of geologic map and geology as a science, could be added. With respect to students 3-D learning abilities, this site provides a useful tutorial and bibliography, based on current learning theory and contemporary pedagogy:

http://www.ldeo.columbia.edu/edu/DLESE/maptutorial/Title_page.html

A good collection of paper models for block diagrams can be found at:
http://www.fault-analysis-group.ucd.ie/

Several of these have been used in class, blanking out part or all of the information as needed.

Others can be found at:
http://reynolds.asu.edu/virtual_reality.htm
http://www.geoblox.com/science.html