Nature at Work

Nature is always fascinating. Inspired from my trips to US western wilderness, this essay features many interesting issues that underlie scientific discovery and exploration. I hope this story would be thought-provoking for every reader. All examples below are drawn from the US states of Arizona, California, Nevada, New Mexico, Texas and Utah (in alphabetical order). Although it represents only a small subset of the vast amounts of natural phenomena on the Earth, I believe it is already enough to illustrate my points vividly.

Canyons! Canyons!

Look at some of the most famous canyons in US. The photos on the right show (from left to right) the Yosemite Valley, the Bryce Canyon, the Grand Canyon, the Zion Canyon and the Red Rock Canyon (bottom). Do they all look more or less the same? Tall mountains, deep valleys, grandeur overlook, and usually accompanied by a river... However, let me tell you the truth: they all bear radically different stories, and belong to contrasting types of formation. Therefore it is not enough to simply know that they are canyons, but we also need to explore and understand the underlying natural forces that shaped the landscape. Nature is at work, and nature is always at work. Let us appreciate the works of mother nature as we go through each detail one by one.

Trees that Form Forests

Stunning Trees

I can see humanity in the trees. There are all kinds of trees in the forest, just like there are all kinds of people in society. Some trees are worth appraisal. They show incredible perseverance and immense courage in harsh environment. Look at the pictures on the left: the leftmost one is an anonymous tree found in Mariposa Grove in Yosemite. The tree was decapitated, yet still survived and maintained its uprightness. The top one is Jeffrey Pine on top of the Sentinel Dome in Yosemite, with an elevation of 7038ft, or 2145m. It is perhaps one of the single most-photographed trees in the world. This lone pine was stricken by lightning before, and gets its nutrients from the granite fissures. In normal circumstances, such pine can grow to about 60ft to 170ft tall. The bottom photo shows a young pine along the Sentinel Dome Trail which leads to the Jeffrey Pine. You can see clearly how the tree was grown right out of a rock. Just like the Jeffrey Pine, it lives on very thin or even non-existent soil!

More Trees

Uninteresting? Trees are the most prominent features of every landscape. You may not see a wild bear in high Sierra, and you may not see a mountain lion in the Rocky Mountain, but you are always promised to see a variety of trees. If you are careful enough, and pay more attention to the vegetation around you, surprises always awaits you, and every trip is worthwhile. The top picture on the right is Monterey Cypress in California. The strong winds shaped the trees there into a distinct form, different from cypress in all other parts of the world. Today, it is still the most popular conifers when introduced into the gardens. The bottom one is a giant sequoia tree taken from the Grant Grove in the Kings Canyon. These trees once roamed the whole North America. Yet changes in weather left the species in only two places, one in high Sierra, another one in north California coast. They are the biggest trees in the world, and are well over 2500 years old. From their thick bark, you can invariably see scars left by wood fires -- the blackened cavity is the heartwood dry-rotted under repeated hot fires. The reddish brown colour of the bark is due to a chemical called tannin, which resists insects, fungi and minor fires. Giant sequoias have very shallow root system but it extends to a wide range. Stepping too close to the tree may destroy their tender roots and topple them over to death.

Forest has its Rules

When put together, trees form forest. The picture on the left is the General Grant Tree, 267ft tall, in the Grant Grove in Kings Canyon National Park. Such tree cannot exist on its own. It seeks shelter from a forest of peers with similar height and other characteristics. The one in the middle is from Muir Woods National Monument and the one on the right is a forest along the Cape Final Trail in Grand Canyon. Although they compete for water, nutrients and sunlight, once in a forest, trees obey an elaborate set of new rules, without which the whole forest would collapse on its own weight!

Put simply, each tree firmly grabs a piece of ground underneath. Even when a tree dies, its root system is decayed just slow enough for new births to take over its place before the soils are washed away. But forest rules are a lot more than that. Each tree competes, not to the detriment of its likes, but in such a way that they complement each other. Trees of the same kind grow to similar height in the same forest, so they don't block each other's share of sunlight too. Do you believe that an acre of forest holds more water than an acre of reservoir? The joint efforts of the trees retain enough water to resists droughts. If not the deforestation brought out by humans that upsets the water balance, forests won't diminish so fast from the surface of our Earth. When a sweep of forest is removed, lands are left bare, and it no longer holds water. Rains wash away the top rich soil, preventing other plants from growing there. Surrounding forests do not receive enough water so they dry out gradually too. This vicious cycle goes on indefinitely until a new water balance could be reached. By that time, we have already lost a huge area of precious woods. Without the trees, weather goes uncontrolled, and often becomes harsh. Nature revenges back on its culprit -- humans.

Fallen Logs

No tree lives forever. When a tree dies, it falls. This is very important -- it falls in order to clear a way for sunlight to penetrate to the ground, enabling new seedlings to grow. The materials in the fallen logs are recycled by mosses, fungi and bacteria. Not a single piece of wood is wasted. Sometimes after a tree falls, its root system is still intact, so new sprouts grow from the remaining root. In Muir Woods, you can see that trees are often tightly grouped into bunches, with trees in each bunch mysteriously arranged in a circle. This is because there was an ancient tree in the middle of the circle. It died, and the trees we see today sprouted from the root of that mother tree. In rare occasions, you can still see a piece of bark of the mother tree remaining in the center of the tree-ring!

If old trees do not die, then new trees cannot grow. As a result, the forest becomes denser and denser. When lightning triggers a fire, which they occasionally do, a dense wood encourages the spread of fire, causing mass destruction. However, natural fire does not mean deforestation, because burnt ashes are good fertilizers, so the forest would regenerate itself quickly afterwards. Also, not all trees would die, otherwise we couldn't have seen those giant sequoias still living today. Recent findings show that periodic fire on a small scale, especially those caused by natural phenomenon like lightning, is good to the health of the forest.

Lively Forests

Forest lives! It has its own life cycle. When fully grown, it looks like the photo on the left, which was taken along Sky Trail in Point Reyes National Seashore. The rightmost photo shows a pretty young forest. After the glacier retreated from Yosemite valley, trees found new paradise here and started to move in, and soon they formed a new forest. The other picture on the right is taken from the Kaibab National Forest in Arizona, near the Grand Canyon. Now, look carefully at both pictures on the right. Do you notice that trees towards the rim of the forest are progressively younger and smaller? Forest grows. It expands by constantly planting new trees along its edge!

Now step back and think -- do you find parallels between a tree and a person, between forest and society? The western civilization has developed good theories of individualism, but they have overlooked the forest. The eastern civilization concerned too much about the well-being of society, to the extent that they ignored individual woods in many respects. Please re-read these paragraphs, substituting person for tree and society for forest. What do you think? Painfully, we are starting to learn how to conserve forests, but regretfully, we still have no idea on how to best run our pluralistic society. Look at how nature works! Can't we get some hints from the trees and the forests?

Water at Work

Life and Water

What is the greatest force in nature? Some may say landslide, earthquake or volcanic eruption, others may say hurricane, typhoon or even tornado, but I would like to argue that water presents the greatest force in nature. Above all, without water, nothing can live, including you and I, the trees and the animals, and at most our Earth could only be a dead planet. The trees in the right is at the entrance of Cottonwood Campsite in Big Bend. It shows the difference of a land with and without irrigation. All civilization need water. Let us begin from the rivers. The rightmost picture shows Riverwalk in San Antonio. As can be imagined, the city originated from the river.

Rivers at Work

So, what can a river do? The pictures on the left show, respectively, the Merced River in Yosemite and the South Fork Kings River in Kings Canyon. Though they all look nice and innocent, they both grew to huge glaciers during the last ice age. New ice formed on top of old ice that survived through summers unmelted, causing the accumulated ice cap to compact on its own weight and gradually filled up the whole canyon. Sand and other abrasives, pressed under the weight of the glacier, literally quarried the rocks, and clove their respective canyon walls to their present grandeur, leaving straitions in the direction of the glacial movement. Yosemite valley is perhaps the most beautiful valley in Sierra Nevada and attracted the largest number of visitors each year, while Kings Canyon is certainly the deepest canyon in north America! Glaciers move extremely slowly that you can walk on it without noticing that the ice beneath is moving at all. However, its sculpting ability is awesome. As a vivid example, the bottom photo on the left is the Royal Arches in Yosemite Valley as seen from the Glacier Point. Notice how the granitic monolith was cleft and the debris carried away by the glacier. As a side note, the flatness of the valley floor was also caused by the river. After the glacier retreated, the Merced river flooded several times, depositing a lot of muds that levelled the ground.

Waterfalls at Work

Sometimes a river comes to a sharp drop, descending into a waterfall. The upper-left photo on the right is Vernal Fall, along the Mist Trail in Yosemite. The bottom-left one shows its base, where the mist, which consists of tiny water droplets, acts as countless mini-prisms that deflect sunlight to give a lovely pair of rainbows whose spectrums expand in opposite directions. Vernal Fall stands 317ft high on Merced River. Like every other fall here, it derives its water mainly from melting snows high up the mountain, so the amount of water decreases towards the end of summer. The upper-right one is Roaring River Fall in Kings Canyon. It is a pretty small fall yet it still comes with great power, roaring loudly. Waterfalls etch away the bedrock, carving the stones and polishing the corners. The lower-right picture is the Lower Yosemite Fall during its dry season in August. The fall left a dark stain of mosses along its path, and you can see clearly how deep the rock was eaten away!

Man-made Dams

When the passage of a river is blocked, then a pool or a lake is formed. Sometimes we construct dams to create artificial lakes too, particularly as reservoirs. The leftmost photo shows a man-made dam at Hat Creek in Lassen Volcanic National Park. The lake was created a few years ago to stock food for use by birds and animals in winter. When the upper part of the lake is frozen, the lower part is still stable at 4 deg Celsius, at which liquid water has the maximum density. The other photo is Hoover Dam built on the Colorado River, at the border of Nevada and Arizona. It is known as the dam with the highest elevation in the world. The dam gave rise to Lake Mead, which supplies water to Las Vegas and surrounding towns in the desert. Lake Mead is also home to many water sports in the Las Vegas vicinity.

Lakes at Work

Instead of eroding materials as in a fast flowing river, lakes have sedimentary effects due to the slow movement of water. Hence, layers of clay, sand and pebbles together with dissolved salts and carbonates are deposited at the bottom of the lakes. In a simplified version, a fast flowing river weathers out the rock, erodes loose pieces, brings them somewhere else, and then deposits them in a slow moving river or lake or delta region. The layers of sediments then compacted, cemented together and lithified to form new rocks.

The top three pictures on the left show the May Lake in Yosemite. The middle one is Emerald Pool, situated between the Vernal Fall and the Neveda Fall, also in Yosemite. The bottom four pictures were taken from Lake Tahoe, the largest and the deepest lake in Sierra. It lies on the border of California and Nevada.

Dying Lake

A lake has both inlets and outlets, which can be rivers or ground water, etc. Isolated lakes without inlets are dying. The large inland body of standing water gradually evaporates, and the lake would first become a marsh, dominated by grasses, then a swamp, dominated by trees, and finally completely taken over by forest. The picture on the right is a dying lake in Yosemite. It was a large lake, so large that it is going to take many years for the water inside to escape completely, therefore it displays all phases of a dying lake at the same time. In the picture, you can easily identify those key features from each of the stages. The place I sit is roughly the boundary between dryland and wetland at that time, and the lake extends much further behind me.

Drying Riverbed

Some lakes are peculiar enough to be seasonal. The Mirror Lake in Yosemite is a good example. It receives water from the Tenaya Creek in spring, grows big enough to capture a breathstaking image of the Half Dome, and then quickly dries out in summer. Seasonal behaviour is also true for some rivers. The Yosemite Fall we have just seen, and its associated Yosemite Creek, are seasonal. The photo on the left shows the riverbed of Rio Grande at Santa Elena Canyon River Access in Big Bend National Park. The receding water left the land cracked under the baking heat of the Sun. The remaining water holds the earth in each of these blocks together, forming this pattern under rapid evaporation. A hierarchy of new cracks appear within each block as the water continue to be evaporated. Eventually when all the water are gone, the pattern also disappears.

Where Land Meets the Sea

Rivers finally flow to the sea. About 97.5% of the Earth's water resides in the ocean, together it covers 2/3 the surface area of the globe. All the pictures on the right are Pacific Ocean at the California coast from Monterey to Big Sur. This part of the land is slowly rising, and the landscape is still very young. Erosion has not caught up with rising land fast enough to make the land slopes gently into the sea.

Nearly all parts of our land were once in the ocean, and most of them has been there several times already. For instance, the southeast shore of US is slowly sinking, and those now in the sea may rise up in the future as highland. In deep sea, skeletons of fish and shells of marine animals sink to the bottom and slowly become limestone. As the land rises past sea level bit by bit, muds of various colours at the mouth of a river become shales, while sand at or near a beach become sandstone.

Where Sea and Lake Worked

There was an ancient sea passage from the Gulf of Mexico, passing through the present-day Colorado plateau, all the way up to the northern part of Canada. The Carlsbad Cavern is carved out of the limestone that formed in deepsea. Even the salt in Salt Lake City owed its origin to this Cretaceous Seaway. The nine photos below are all situated in the affected regions. Now look carefully at the layers of rocks at the Grand Canyon (bottom three photos) and try to identify these different rocks.

Depository and Erosionary Effects of Water

It is not the end of the story yet -- as the seaway retreated, a Claron Lake System was formed in the present place of Zion Canyon (middle three photos) and Bryce Canyon (upper right photo), which collected further deposits from surrounding rivers. The top layer at Grand Canyon is still quite old -- it is the bottom layer at Zion Canyon, while the top layer at Zion Canyon is the bottom layer at Bryce Canyon. So by visiting all three parks, you get a complete picture of the geological history of our Earth.

Red Canyon (the two photos in the top-left) is next to the Bryce Canyon. The UT-12 highway that leads to Bryce Canyon passes through the Red Canyon. Together with Cedar Breaks National Monument and Bryce Canyon, they share similar history of formation. Red Canyon is like a miniature of Bryce Canyon, the closeup pictures of hoodoos you see in Red Canyon is replicated millions of times in Bryce Canyon, as seen in the upper right photo. However, no two hoodoos are the same. They all display unique postures.

Rain & Ice at Work

Water contributed a lot to many interesting landscapes. Bryce Canyon is populated with hoodoos like the one on the left. These layered rocks were deposited in the Cretaceous Seaway and Claron Lake System, etc. However, they are washed not by rivers but by rains and wind. In winter, water droplets freeze into ice in the rock fissures. As the ice expands in volume with respect to its parent liquid form, it cracks the rocks. When it rains, the loose pieces are brought away. These hoodoos are shaped out by repeated freezing and washing year after year. The bottom picture shows a natural bridge, also formed this way. The wonder of water is endless. And no matter which form water takes, no matter where the water is, it is always at work, creating marvels.

Penetration of Water

The photo on the right is the Weeping Rock in Zion Canyon. Rainwater passes through layers of porous or tractured rocks until it reaches an impermeable one, then it flows horizontally and finally comes out here, dripping off the walls of the canyon, like somebody weeping in sorrow. When the Colorado Plateau is uplifted, the Vigin River sawed its way down as the land rose. Landslides occur where the sculpted pieces are unstable. It widened the canyon walls and blocked the passage of the river, causing it to flood, which in turn leveled the canyon floor.

So the humblest force in nature, water, does the greatest job. While other forces like earthquake or volcanoes are sudden and often destructive, works of water are slow but persistent. It is erosionary in some places yet depository in others. As a whole, it redistributes materials and is the greatest sculptor of our landscape. Water also nourishes life, and is crucial in the formation of a spectrum of beautiful phenomena from rainbows to cracking land. None of these could be achieved with any of those more violent and so-called more powerful forces.

Chinese movies and novels often depict that the strong is overcome by the weak, or an all-powerful weapon can excel everything but the most primitive tools. Western people often don't understand the reason and could only attribute it to magic. However, there is no magic inside. Once you understand why the most humble force is the greatest, you start to appreciate it. Jesus also told us whoever wants to be the leader has to become the servant of all. Isn't it the same principle? Armament race cannot alleviate our pains but only aggravates them; money and political power is not the solution to everything but often the roots of evil when misused, as is usually the case. People now talk about tolerance as a way to address problems in pluralistic society, but they still try every method to get "stronger" and "stronger". I think we need to do more -- tolerance is not enough, and we need to get humble and start to understand each other. Water can penetrate through a rock which the sharpest knife cannot cut through.

Disquieted Land

To Conquer or to Maintain Harmony?

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