Apr

6

 Egged on by arguments raised by the recent change in Administrations, and the white-hot debates generated by the "climate change" brouhaha, a glance at the field of geomorphism, the science of how the Earth changes over time, its forces and contributors, seems a plausible and worthwhile effort.

The average citizen pays little attention to the less sexy but commanding aspects of erosion, relying unfortunately on the headline tropism that provides little in the way of actual explanations or in-depth nuance. Icecaps melting! Shout the tabloid media. Island sinking by 2015, foretold a former Vice President, now proven comically overbloated in his prognostications, highly remunerated speeches and fizzled films.

But let us consider more than headlines in regard to geomorphism, which might reclaim some measure of moderation in thinking about the hubbub over change over the planet.

The geomorphologist has to consider multiple factors in trying to interpret how hills and valleys came to be. This includes the timing of these erosive elements, and what these geologic features look like over the march of years. Erosion as an umbrella overall is a key tab, but occurs at differing rates within a delicatessen of timescales based on rainfall, climate,, vegetation, , composition and homogeneity of rocks, fractures, fissures, landslides,

avalanches, riverine sedimentation and carrying capacity and, often overlooked but supremely important, slope. Nor can the geomorphologist ignore sunrises, sunsets, and even persistent shadows cast by crags and crests, blanking out sunlight for large swathes of day.

Remembering, too, the silent gnomes: Moon and tides, vestigial but vestal.

Instances of data are mobile, note, where the rate of erosion at the surface is offset by the never-ending fores of uplift/gradual upheaval ongoing as constantly, if incrementally, in many latitudes. For word lovers, this is denudational isostatic rebound. (For analogy and lingerie lovers, this can be likened to cunning covered underwires, for bosom support architecture.)

There are some 'easier' rules of gauge—with higher ascents and steeper mountain ridges eroding relatively swiftly: the East Himalayas erode at a whopping 2 to 3 mm per annum, for example. Such erosional rates, themselves, will evolve over time, as well, to meet new equilibrial homeostasis–depending on weather and wear forces noted above. (Such erosional rates hold steady for all earthly features except, one can posit, stubborn body fat, which defies discernible erosion for decades, seemingly.)

"Don't think we'll ever find the single smoking gun of erosion," according to pooh-bah Eric W. Portenga, bishop of Earth & Environmental Sciences at the University of Michigan. "The natural world is so complex, and there are so many factors that contribute to how landscapes change over time." As his measurement paradigm manages to gain foothold in the field of geomorphology, we will glean a better sense of what variables are vital, and which are not, in the erosion saga.

For decades, it has been a geology truism that rainfall is erosion's master driver. Semi-arid landscapes with sparse vegetation, yet the occasional major storm were thought to manifest the greatest grids of wear. But an important study challenges that 'bedrock' idea.

"It turns out the greatest control of erosion is not mean annual precipitation," notes theorist Paul R. Bierman, of the University of Vermont.

Instead, regardez slope.

"People always thought angle was a big deal," says Bierman. "But the data show slope is really important." Who would have thought?

(As with phalli, the angle is critical, for impregnation, as well, of course, as pleasuring.) So the land's angle, the naked scree and tree-root tangle, all fall to the mean—entropy flattening at the smallest suggestion, evolution's Zamboni edge.

Some of course prefer more direct and more calculable methodologies, ways of measuring the vales and hollows and their duration or extinction. Practitioners in this still-emerging field draw from the arenas of physics, biology, chemistry and math to arrive at a more graphic understanding of terrestrial surface processes and the evolution of topography over short-term and longer-term timescales.

We are clearly not yet at the certitude we seek. Needed is a Dionysian, geologic Dian Fossey, the recent Sam Pepys of primatology. Geologists and statisticians need rules of less-than-dumb thumb for figuring the whys, hows and whats of Earth's dynamic surface, translatable to our Earthly rocky past. And hopeful learned future.

Scant evidence, we propose (tongue in left cheek), of a gneiss Deity?


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