Posted by: chrismaser | March 9, 2010

NATURE’S INVIOLATE PRINCIPLES: 14

DYNAMIC DISEQUILIBRIUM RULES ALL SYSTEMS

If change is a universal constant in which nothing is static, what is a natural state? In answering this question, it becomes apparent that the balance of Nature in the classical sense (disturb Nature and Nature will return to its former state after the disturbance is removed) does not hold. In fact, the so-called balance of Nature is a romanticized figment of the human imagination, something we conjured to fit our snapshot image of the world in which we live. In reality, Nature exists in a continual state of ever-shifting disequilibrium, wherein ecosystems are entrained in the irreversible process of change, thereby altering their composition, interactive feedback loops, and thus the use of available resources—irrespective of human influence. Perhaps the most outstanding evidence that an ecosystem is subject to constant change and disruption rather than remaining in a static balance comes from studies of naturally occurring external factors that dislocate ecosystems, and climate appears to be foremost among these factors.

After a fire, earthquake, volcanic eruption, flood, hurricane, or landslide, for example, a biological system may eventually be able to approximate what it was through resilience—the ability of the system to retain the integrity of its basic relationships. But regardless of how closely an ecosystem might approximate its former state following a disturbance, the existence of every ecosystem is a tenuous balancing act because every system is in continual state of reorganization that occurs over various scales of time, from the cycle of an old forest to the geological history of Zion National Park in the State of Utah.

Bear in mind, an old forest that is burned, blown over in a hurricane, or smashed in a tsunami, could be replaced by another, albeit different, old forest on the same acreage. In this way, despite a repetitive disturbance regime, a forest ecosystem can remain a forest ecosystem. Thus, ancient forests around the world have been evolving from one critical state to the next, from one natural catastrophe to the next.

On the other hand, formation of the canyon in Zion National Park has a much longer history than any of the world’s forest. Where today the deep canyons and massive walls of stone enthrall visitors, 245 million years ago a sea covered the area that was populated by marine fishes. Over a period of roughly 35 million years, about 1,800 feet (549 meters) of sediments were deposited on the floor of the sea, along the coastal plain, and along the inland streams.

As the climate warmed, the sea changed into a gigantic swamp. Here, 210 million years ago, crocodile-like, plant-eating dinosaurs swam in the sluggish streams whose floods carried drifted trees on their swirling waters from distant forests to form logjams. Here too, small, fragile dinosaurs hunted along the streams banks. But as the climate once again became moister during the next 40 million years, the swamp became a lake and the sand, silt, and clayey mud of the streams and the swamp gradually hardened into rock.

The lake for a time had fish living in it, but then some of its waters became shallow and eventually disappeared. And existing streams spread silt and sandy mud over the sediments deposited on the lake’s bottom. Toward the end of this 40-million-year interval, the climate began to dry, and in a short space of time, geologically speaking, the now-intermittent streams deposited more sediments.

Then, about 170 million years ago, the ancient sea, the swamp, the lake, and the intermittent streams became buried beneath a desert of marching sand dunes. This now-hostile environment had little life associated with it, and the few hardy plants and animals that did exist often died during the great storms that blew clouds of hot, dry sand into dunes. As the dunes were built, destroyed, and built again, some of the plants and animals became entombed and are the rare fossils of today in what is now the sandstone, ranging from 1,500 to 2,000 feet (457 to 610 meters) thick. Although the source of the sand eroded away 150 million years ago, evidence indicates that it had been a region of highlands in what is today the state of Nevada.

For a brief period following the creation of the desert, floodwaters, carrying suspended sediments, buried the dunes in deposits of red mud, after which the climate returned to more desert-like conditions.

Again the climate changed, and 145 million years ago a vast, shallow sea once more covered the area, drowning the desert. Now the once-sterile desert, with its cap of red mud, became the floor of the sea and the home of sea lilies (crinoids) and of shellfish. But when the warm, teeming waters once again retreated, they left behind, buried in limey silt, shells that produce the present-day fossils.

Over the millions of years, in response to changing environmental conditions, various materials were deposited in the sediments. The Zion area experienced shallow seas, coastal plains, a giant swamp, a lake, intermittent streams, and a desert filled with massive, wind-blown dunes of sand. While the shallow seas covered the area, mineral-laden waters slowly filtered down through the layers of sediment. Minerals like iron and calcium carbonate were deposited in the spaces between the particles of silt, sand, and mud, cementing them together, thereby turning them into stone. And the weight of each layer caused the basin to sink and maintained its surface at an elevation near sea level. This process of deposition-sinking-deposition-sinking continued layer upon layer until the accumulation of the successive sediments became 10,000 feet (3,048 meters) thick.

Geologists believe that Zion was a relatively flat basin with an elevation near sea level from 245 million years ago until the last shallow sea dried, about 10 million years ago. At that time, Zion was a featureless plain across which streams meandered lazily as they dropped their loads of sediment in sandbars and floodplains.

Then, in an area extending from Zion to the Rocky Mountains, a massive geologic event began. Forces deep within the Earth’s mantle started to push upward on the surface of the Earth. The land in Zion rose from near sea level to as much as 10,000 feet (3,048 meters) above sea level.

Zion’s location on the western edge of the uplift caused the streams to tumble off the Colorado plateau, flowing rapidly down a steep gradient. The Virgin River is illustrative because it drops more than 4,000 feet (1,219 meters) from the northeast corner of Zion National Park in Utah to Lake Mead in Arizona, 145 miles away; in comparison, the upper Mississippi River drops only 210 feet (64 meters) from Lake Itasca, in the state of Minnesota, to Grand Rapids, also in the state of Minnesota, also a distance of 145 miles.

And because fast-flowing water carries more sediments and larger boulders than does slow-moving water, these swift streams in Zion began eroding down into the layers of rock, cutting deep, narrow canyons. In the 10,000 years since the uplift began, the North Fork of the Virgin River has both carved Zion Canyon and carried away a layer of rock nearly 5,000 feet (1,524 meters) thick, a layer that once lay above the highest existing rock in the park.

The uplift of the land is still occurring, so the Virgin River is still excavating. The river, with its load of sand, has been likened to an ever-moving strip of sandpaper. Its grating effect, coupled with the steepness of the Colorado Plateau, has allowed the river to cut its way through the sandstone in a short time, geologically speaking.

The cutting of Zion Canyon created a gap in the solid layer of resistant sandstone, and the walls of the canyon relaxed and expanded ever so slightly toward this opening. Because rock is generally rigid, this expansion caused cracks, known as pressure-release joints, to form inside of the canyon’s walls. These cracks run parallel to the canyon about 15 to 30 feet (4.6 to 9.0 meters) inside the walls, and occur throughout the sandstone.

The grains of sand that form the sandstone itself were once driven bouncing across the desert by the wind, only to be caught within the steep face of a dune, where they became buried. Over time, the cement of lime tied grain-to-grain creating the stone of sand.

That process is now reversed, and a new cycle has begun. The layer of siltstone directly beneath the sandstone is softer and more easily eroded than the sandstone. Thus, as the walls of sandstone are undermined by the erosion of this softer material, water from rain and snow seeps into the joints, where it freezes in winter, wedging the walls of the joints ever further apart.

In addition to freezing, the water, one drop of rain at a time, one melting flake of snow at a time, aided by chemical action, dissolves the cement. The structure gradually weakens, until a last grain of sand holding the undermined wall in place moves, and the massive piece of rock falls. Breaking away along the line of least resistance, it leaves the graceful sweep of a huge arch sculpted in the face of the cliff a 1,000 feet (305 meters) above the floor of the canyon. And so is revealed yet another vertical face previously hidden as a crack or pressure-release joint inside the wall. Below, the rock, shattered by the fall, gradually returns to sand and is once again blown hither and yon by the wind or carried toward the sea by the restless Virgin River.

In the end, Zion, cemented together grain by grain over millions of years, is being dissolved over millions of years one grain at a time by the persistence of water from rain and melting snow. But while Zion undergoes its inevitable changes, it is the home for 670 species of flowering plants and ferns, 30 species of amphibians and reptiles, 125 species of resident birds, and 95 species of mammals. Nevertheless, the wolf, grizzly bear, and native bighorn sheep are gone, extirpated within the last 150 years or so by the invading European-American settlers. Thus are tipped once again the scales of disequilibrium in all its dimensions.1


 

Related Posts:
 

• The Law Of Cosmic Unification

• Principle 1: Everything is a relationship

• Principle 2: All relationships are inclusive and productive.

• Principle 3: The only true investment is energy from sunlight.

• Principle 4: All systems are defined by their function.

• Principle 5: All relationships result in a transfer of energy.

• Principle 6: All relationships are self-reinforcing feedback loops.

• Principle 7: All relationships have one or more tradeoffs.

• Principle 8: Change is a process of eternal becoming.

• Principle 9: All relationships are irreversible.

• Principle 10: All systems are based on composition, structure, and          function.

• Principle 11: All systems have cumulative effects, lag periods, and           thresholds.

• Principle 12: All systems are cyclical, but none are perfect circles.

• Principle 13: Systemic change is based on self-organized criticality.

• What Is A Commons?

• Why Be Concerned With The Building Blocks Of Sustainable Planning

• The World Is In My Garden–My Garden As Metaphor

• What Is A Commons?

• Biodiversity–The Variety Of Life

• Soil–The Great Placenta

• Air–The Breath Of Life

• Water–A Captive Of Gravity

 


ENDNOTE

  1. The foregoing discussion of Zion National Park is based on: A.J. Eardley and James W. Schaack. Zion: The Story Behind the Scenery. KC Publications, Inc., Las Vegas, Nevada. (1989) 46 pp.


Text © by Chris Maser 2010. All rights reserved.

Protected by Copyscape Web Copyright Protection


This series of blogs is excerpted from my 2009 book, Social-Environmental Planning: The Design Interface Between Everyforest and Everycity, CRC Press, Boca Raton, FL. 321 pp.

If you want to contact me, you can visit my website. If you wish, you can also read an article about what is important to me and/or you can listen to me give a presentation.



Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Categories

%d bloggers like this: