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Learning to Think Spatially: GIS as a Support System in the K-12 Curriculum
http://www.nap.edu/catalog/11019.html
SPATIAL THINKING IN EVERYDAY LIFE, AT WORK, AND IN SCIENCE 81
Consider the example of global atmospheric circulation. Certainly, the existence and orientation
of trade winds, a fundamental observation, was known from long ago. Yet the northward
counterflow at high altitude cannot have been documented observationally by those pioneers; they
must have inferred it and included it in their mental picture because the picture did not make
physical sense without it. Some of the great leaps of visualization of three-dimensional Earth
processes have progressed by a hybrid process, in which the visualization is partly shaped by data
and observations and partly by intuitive understanding of driving forces. Modern models of oceanic
and atmospheric circulation try to formalize this hybrid cognitive process. The models are built
around equations that purport to represent physical forces, and then data are used to “train” the
models through a process of “data assimilation.”
Envisioning the Processes by Which Objects Change Shape
Whereas the fluid parts of the Earth system generally respond to imposed forces by moving
through space, the solid parts may respond by changing their shape, by deforming, by folding, and
by faulting. After struggling to visualize the internal three-dimensional structure of a rock body, the
geologist’s next step is often to try to figure out the sequence of folding and faulting events that has
created the observed structures. This task may be attacked either forwards or backwards: backwards,
by “unfolding” the folds and “unfaulting” the faults; or forwards, by applying various
combinations of folds and faults to an initially undeformed sequence of rock layers until you find a
combination that resembles the observed structure (Figure 3.27). The forward approach resembles
the paper-folding task used by psychologists who study spatial thinking (see Chapter 2).
Elements of solid Earth also change their shape through erosion, through the uneven removal
of parts of a whole. Thinking about eroded terrains requires the ability to envision negative spaces,
the shape and internal structure of the material that is no longer present.
Using Spatial Thinking to Think About Time
It is common in thinking about Earth to find that variation or progression through space is
closely connected with variation or progression through time. For example, within a basin of
undeformed sedimentary rocks, the downward direction corresponds to increasing time since deposition.
On the seafloor, distance away from the mid-ocean ridge spreading center corresponds to
increasing time since the formation of that sliver of seafloor.
As a consequence, geologists often think about distance in space when they really want to think
FIGURE 3.27 Mentally manipulating a volume by folding, faulting, and eroding: geometry of the lower
duplex at Hénaux. SOURCE: Ramsay and Huber, 1987. Copyright 1987, reprinted with permission from
Elsevier.
Copyright © National Academy of Sciences. All rights reserved.