In my last few posts I described how the most promising way of capturing and “compressing” long gradients (ranging over hundreds of miles) in temperature or precipitation would be a photographic transect made up of ground-level views shot at even intervals along the gradient and arranged in a sequence. I’ve mentioned that to add interest, clarity, and context, that sequence could be complemented by additional types of imagery. Here are some more thoughts on what that larger display might include:
The photo-transect itself, combining enough views to create an “average” picture of the gradient that outweighs local irregularities. This could be anywhere from a few dozen to a few hundred views depending on the length of the gradient (a few hundred to a few thousand miles) and the size of the interval (say between 1 and 10 miles).
A baseline—the first image of the transect repeated over and over, “measuring” the gradual change in the transect that would be otherwise imperceptible photo-to-photo. For example each image in a rainforest-to-desert transect would be aligned with the initial rainforest image.
Gradient milestones marking significant moments, like the first appearance of a certain species. It would take the form of a single image here and there aligned with its location in relation to the transect. Those images could be duplicated images from the transect, additional images where the transect interval or route happens to miss those locations, or a combination.
A very, very long overall aerial photograph with the route of travel highlighted.
Zoomed-in aerials—enlarged portions of the overall aerial—each aligned with each image in the transect (essentially an aerial counterpart to each transect image).
Data, like graphs showing spatial changes in temperature/precipitation or the ranges of various species along the gradient.
Diagrammatic exhibit incorporating a photo-transect (in this case along a precipitation gradient) with supporting imagery, numbered according to the above outline. In actuality it would be much, much longer.
In the process of writing these posts I’m coming to the conclusion that if I ever do have a chance to document one of these long gradients more methodically, this approach probably wouldn’t be very engaging to someone not already interested in the subject. Aside from being challenging to create and then fit onto a wall, the result would probably be information overload. I’m not intending it to be artistic—it would be more along the lines of something you’d see in a design exhibition—and that might be the problem. I’ve explained why the “fractured” style I use to represent short gradients wouldn’t work in this case, but I think I might need to sacrifice some subtlety to move back in that more creative direction.
I’m confident that some version or subset of the outline above can be made to work—all that information could be useful in some form. But I thought I’d mention a different kind of “measure” of these gradients which could still capture the subtlety of the gradient while mostly avoiding the subtlety and complexity of vegetation as a measuring device: built form. On this past winter’s cross-country road trip the idea occurred to me to use Google Maps to count the frequency of rectangular vs. circular farm fields in a band along the highway, as an indication of increasing aridity traveling east to west (the two forms use different methods of irrigation). You can observe and quantify the presence or absence of a certain built/designed element much more easily than, say, a tree species that can vary in size and health (should the first instance of a species count as a “milestone” if it’s just a seedling or if it’s half-dead?). The choices are discrete, if not binary. There are a number of other built elements, material and stylistic, responding to temperature or precipitation that could be quantified in this way. On the trip I also noticed that at some point in Oklahoma, stone or brown-painted highway overpasses started replacing green-painted ones. I wasn’t paying full attention and so I’m sure there were more bridge designs than that, but the fact remains that they’d be relatively straightforward to categorize and count. This type of documentation wouldn’t necessarily require a photo-transect at all, probably just an aerial image overlaid with symbols: The sense of immersion provided by on-the-ground photography would much less important to conveying building patterns than conveying vegetation patterns. (And in some cases the counting itself could be done with satellite imagery or Google Street View rather than all that field work.) It still wouldn’t be a work of art, but it would be more manageable in every way.
A wet-dry gradient illustrated by quantifying the frequency of rectangular vs circular fields, represented respectively by blue and red dots on an aerial photograph. (Satellite images from Google Maps.)
In graduate school, reviewing a proposal (ultimately unsuccessful) I’d written to create one of these photo-transects, a professor noted a particular tunnel through the Alps that acts as a dividing line between “northern” shingled roofs and “southern” tiled roofs. If the boundary really is that sharp, then it actually represents a “milestone” along a temperature/precipitation gradient that’s certainly more gradual even if the climates on either side of the mountain or ridgeline above that tunnel are distinctly different. As with a vegetational milestone, that would be especially powerful—the boundary would distill and compress a much more subtle climatic gradient into a clear, single line.
That should wrap up my thoughts on representation for the time being—next time I’ll have more to say, and show, on other long gradients around the world….
Darren