Tuesday, June 30, 2009

Birding the Canopy

While we associate birds with trees, most of the species recognized by the general public are those that inhabit the shrubbery, feed on the ground or readily come to feeders; cardinals, mourning doves, crows, chickadees, house sparrows, blue jays, robins, starlings, goldfinches, hummingbirds, flickers and pigeons come to mind. On the other hand, birds that inhabit and feed in the forest canopy are essentially unknown to most people and can be a challenge to observe, even for the avid birder.

Tanagers, red-eyed vireos, yellow-throated warblers, cedar wax-wings, great crested flycatchers, warbling vireos, yellow-throated vireos and a variety of small flycatchers are among the species that favor the upper branches of woodlands. The best way to observe many of these birds is to visit a gorge or stream valley where hilltop overlooks or rock outcrops offer a view of trees from above. At such locations, a birder can view the canopy at a comfortable angle and observe the avian residents without enduring neck strain; in addition, the birds can usually be observed in good light (in contrast to their shadowy appearance from the ground).

By taking advantage of the topography, beginning bird watchers may rapidly add a new group of species to their life list. Indeed, this convenient means of observing common but hidden species may prove just as rewarding as travelling to other parts of the country. Stuck in our routines of exploration, we often overlook the diversity of our home environment.

Monday, June 29, 2009

Complexity and God

Anyone with an interest in science soon begins to appreciate the amazing complexity of our Universe. Even a superficial attempt to understand the natural world leads to an overwhelming spectrum of physical forces, chemical reactions and biological systems; and those who spend their life focusing on a narrow field of science are even more aware of nature's complexity. In medicine, for example, every biochemical process is modified by a vast array of agents which enhance or inhibit that process; in turn, the production, expression or destruction of these modifying agents is dependent upon another layer of genetic and/or environmental factors (not to mention forces and particles at the atomic level).

Religious persons point to this complexity as evidence of a Supreme Being who created and apparently micromanages our Universe. At the same time, they accept simplistic biblical stories (such as Noah's Ark) and imagine that God responds to our individual prayers, interceding in life events from major illness to little league games. Of course, most devout believers have little or no science education and their Churches have a long history of attempting to derail scientific progress.

On the other hand, most academic scientists, having a deep appreciation for the complexity of this Universe, do not accept the presence of God, at least not the simplified, humanized Deity of Western Religions. For them, and for me, it is difficult to attribute the presence of this vast yet intricate Universe to a meddling and vindictive God. Any Power great enough to have even imagined such complexity would insist on intellectual honesty.

Sunday, June 28, 2009

A Dramatic Recovery

The end to our two week stretch of hot, humid weather came at 9PM last evening as a line of thunderstorms struck Columbia from the northwest. The leading edge of a cold front, the storms produced torrential rain and an hour of persistent thunder and lightening.

This morning, the front has pushed off to the southeast and we have a gentle, northwest wind, pushing in cooler, drier air. Sitting at 68 degrees F, we are ten degrees below some morning readings over the recent heat wave and today's high is expected to remain in the mid eighties.

Outdoor activities will become tolerable once again and the air conditioners will get a much deserved break (at least from our financial perspective). Sultry weather will be confined to the Gulf Coast States for now, our fixation on the heat with subside and summer will regain its glorious image of our childhood memories. But our risk for oppressive heat and humidity will loom for another ten weeks.

Friday, June 26, 2009

Earth's Vital Blanket

While Earth's atmosphere is more than 300 miles thick, gravity keeps 80% of its mass within the Troposphere, the layer closest to our planet's surface. About 5 miles thick near the Poles, the Troposphere balloons to 11 miles at the equator, an effect of Earth's rotation; even here, its thickness is minuscule when compared to our planet's radius (almost 4000 miles).

Composed of 78% nitrogen, 21% oxygen and 1% argon, the atmosphere contains a variable amount of water vapor, carbon dioxide, particulates, methane, nitrous oxide and sulfides; these variable components, though generally in very small concentrations, are responsible for our weather and our climate. With the exception of the tallest thunderstorms at mid latitudes (which may poke into the Stratosphere), all of Earth's weather occurs within the Troposphere and it is this "low altitude" band that is primarily subject to pollution; indeed, two thirds of its mass is found below 18,000 feet.

The ozone layer, which absorbs ultraviolet light and other ionizing radiation, is vital to all life on Earth (at least to all species on land and in the upper waters of the sea). This band, about 6 miles thick, lies just above the Troposphere, at its interface with the Stratosphere. Unlike the ozone near Earth's surface (a pollutant resulting from solar radiation acting on industrial and vehicle emissions), this protective layer of ozone results from the ionization of oxygen molecules in the Stratosphere. Holes in the ozone layer, first discovered in the 1980s, have been attributed to pollutants (especially chlorofluorocarbons) in the underlying Troposphere. Once again, human activity may be slowly destroying the natural environment that permitted our own evolution.

Thursday, June 25, 2009

Zealots and Hypocrites

Over the past week, two high profile,"Christian-Conservative, pro-family" politicians have been caught in extramarital affairs. Such a disconnect, between expressed beliefs and concealed behavior, has been going on throughout recorded history and, likely, since the dawn of man.

Profoundly devout individuals are often masking "sinful action" (real or imagined) in their own lives. Anti-gay politicians and religious leaders frequently turn out to be homosexual themselves or are appeasing their homophobic emotions. War hawks, usually politicians or media pundits, have often never been in battle; they engage the enemy from the safety of their office or studio. Politicians who want government out of our lives often shower their constituents with federal handouts and conservatives who oppose Washington's meddling in our finances favor federal laws that govern our personal behavior.

Humans are often outwardly bombastic while personally insecure. We enjoy the admiration of others while knowing, deep down, that we don't deserve it. We tend to hide our own inadequacies (real or imagined) by demonstrating a strong devotion to their cure and, the more we have to hide, the more zealous we become. What society needs is more tolerance and less hypocrisy.

Wednesday, June 24, 2009

Weather on the Rim

Over the past week, a massive dome of high pressure has brought extreme heat to the southern U.S.; in the past few days, this atmospheric ridge has drifted westward and has bulged further to the north. Within the dome, where the air is sinking, hot, humid conditions and light winds prevail.

The weather action is along the rim of this ridge where this tropical air converges with cooler, drier air of the High Plains and Upper Midwest. Thunderstorms develop in this collision zone and, due to clockwise flow around the edge of the dome, these storms move in that direction. Lying near the west edge of the rim, the Front Range of Colorado is experiencing an early monsoon season; the heavy rains of that period generally occur in August, in response to similar high pressure over the Southern Plains. In the past week, bands of thunderstorms have also brought torrential rains to the Northern Plains and Upper Midwest as the dome has pushed into those areas. Florida, initially encased within the dome, experienced record high temperatures as the usual sea breeze was shut off; since the ridge has shifted northwestward, this onshore flow has redeveloped in South Florida, producing heavy rains across that region. Meanwhile, as this persistent dome has shunted cold fronts into Canada, the Northeast remains trapped in a stationary trough, with cool, damp conditions more typical of spring.

Last evening, a ripple in the north rim of the dome produced a cluster of thunderstorms which had enough punch to invade the ridge. Moving south, they reached Central Missouri about 10PM, producing strong winds and heavy rain. This morning, the air is noticeably cooler and drier than it has been; unfortunately, the ridge is expected to build back from the south and hot, humid conditions should redevelop by this afternoon.

Tuesday, June 23, 2009

The Eastern Divide

The Continental Divide of North America is well known for its rugged peaks and high passes. But there is a lesser known and more subtle divide in the eastern U.S., which separates the streams flowing toward the Gulf of Mexico from those draining to the Atlantic.

After snaking across the arrowhead of Minnesota, the Eastern Divide loops past Duluth and heads across northern Wisconsin. Turning south, it passes between the watersheds of the Wisconsin River and Lake Michigan, curves through Metro Chicago and hugs the northern edge of northwest Indiana; the Divide then dips toward Lima, Ohio, below the watersheds of the St. Joseph and Maumee Rivers. Crossing northern Ohio, this line of high ground passes north of Youngstown, cuts the northwest corner of Pennsylvania and loops through southwest New York, following the edge of the Allegheny River watershed. Angling to the southwest, the Divide climbs atop the Allegheny Front of Pennsylvania and then forms the west edge of the Potomac River watershed in Maryland and West Virginia. Entering Virginia, it follows the crest of the Appalachian Mountains as far south as northern Georgia.

Winding southward through the Peach State, the Eastern Divide passes near Atlanta and then angles southeastward toward Waycross, Georgia. There it continues southward between the watersheds of the Suwanee and St. John Rivers and snakes down the Florida Peninsula to Lake Okeechobee; south of the Lake, the Everglades diffuse the flow between the southeastern Gulf Coast and the Florida Strait. Following the Eastern Divide from Minnesota to Florida would surely be an interesting journey and would introduce the traveller to most natural ecosystems of the eastern U.S.

Monday, June 22, 2009

Death Watch

Modern science is now able to explain most aspects of our lives though details will continue to unfold over time. But while we know a great deal about the processes of living and dying, we will never be sure about the presence or absence of an afterlife. This great mystery, long a source of fear, anxiety and wonder, will escape the scrutiny of science.

Humans are the only animal with the intellectual capacity to anticipate death and, since our earliest days on the planet, we have developed rituals and beliefs to quell the emotions induced by that knowledge. Religious persons "know" what to expect and psychics profess the ability to communicate with the dead. But they, as well as the rest of us, are drawn to the subject like no other.

Our fascination with death and dying is exploited by the media; this week's tragic slaying of a young woman in Iran, caught on video, will become the latest exhibit in a morbid collection that dates back to the Zapruder film and beyond. Murder mysteries blanket the airwaves, detailing the brutal deaths of innocent victims. News coverage of accidental death, while important in the context of cause and prevention, often focuses on the presumed mechanism of injury, stirring the imagination of a curious public. We need to watch. We need to know. It is, after all, one certain event in our future.

Sunday, June 21, 2009

Nature and Fatherhood

Throughout most of the animal kingdom, fatherhood is nothing more than sperm donation. While there are some species (primarily birds) in which the male contributes to child rearing, it is usually the mother that handles any post-conception duties; of course, in lower animals, even her responsibilities may be minimal.

In most mammals, the father also relinquishes responsibility after fertilization and the practice of monogamy (to the extent that it occurs) is limited to humans. Whether monogamy and long-term family attachments are natural human traits is a subject of debate but few would argue the importance of devoted fathers in modern society. Nevertheless, the rise of fatherhood, while revered and cherished in most human cultures, is superimposed on natural tensions that arise within the family unit. How the father deals with these innate challenges will, in the end, make all the difference.

Today, we honor men who, despite their natural tendencies, have welcomed and fulfilled the responsibilities of fatherhood. Their commitment is vital to the welfare of families and, indeed, to the stability of human civilization.

Saturday, June 20, 2009

Tropical Kansas

Leaving Denver this morning, low clouds and curtains of virga hung in the eastern sky. A few showers dampened the Interstate across the High Plains, giving way to steady rain just east of Oakley, Kansas. The precipitation intensified as we continued to the east, with periods of torrential rain, like the bands of a tropical storm; despite the deluge, no lightening, high winds or hail accompanied the downpours. This heavy rain persisted, with only brief interruptions, all the way to Junction City.

Over the past week, a dome of high pressure has settled over the Southeast and South-Central States. Along its rim, where the hot, humid air of the dome collides with cooler air of the Central Plains and Midwest, thunderstorms and heavy rain have developed, moving clockwise around its edge. Today's torrential rain along I-70 fell across the northwest section of that rim; once we left the collision zone (east of Junction City) and entered the hot, soupy air of the dome, we could see its northern curve in the distance, represented by storm clouds across northeastern Kansas and northern Missouri.

Though I have no forecasting credentials, I would expect significant flooding along the Smoky Hill River in the coming days. The entire stretch of today's downpour, some 230 miles in length, is drained by that River and its northern tributaries.

Friday, June 19, 2009

A Farm in June

Arriving at our Littleton farm, we found the foliage more lush and green than at any time since we bought the property (in 1990), a testament to recent storms and heavy rain. The pastures have grass as high as the fences and the trees and shrubs, often stressed by the semiarid climate of Colorado's Front Range, were as verdant as ever. Fortunately for us, sunny, mild days and clear, cool nights persisted during our visit.

Ripening mulberries and our ever-abundant juniper crop attracted flocks of robins, northern orioles and house finches while bushtits, chickadees, flickers and house wrens scoured the woodlots. Sharp-shinned hawks occasionally strafed the farm, hoping to snatch an unwary songbird, and Swainson's hawks soared above the fields. Double-crested cormorants, great blue herons, mallards and Canada geese often passed overhead and, in the evenings, black-crowned night herons moved toward the South Platte River. Though, with the exception of fox squirrels, mammals were seldom encountered, their calls, musk and carrion told of nocturnal hunts. As is typical in June, garter snakes were abundant on the farm, feasting on earthworms, young mice and on the growing hordes of insects.

Prairie flax, roses and spirea offered pockets of color but rich greens and a deep blue sky dominated the scenery. Though yard work and maintenance occupied much of our time, this background of natural splendor was, as always, the highlight of our visit. A farm in June in Colorado: is there a better place to be?

Wednesday, June 17, 2009

Colorado's Cloud Mountains

Those of us who live along the Colorado Front Range can become complacent about the snow-capped summits to our west. They have, after all, been there for 65 million years, their size and shape an ever-changing product of uplift and erosion. Today, many of the Front Range peaks soar above 13,000 feet, with a few exceeding 14,000 feet.

But these terrestrial landforms pale in comparison to the cloud mountains that billow above our Eastern Plains during the thunderstorm outbreaks of June. This year, the number and severity of these monster storms has been well above average, leaving this semiarid region with greenery more typical of the eastern U.S. Forming above the Front Range by mid afternoon, the storms are swept eastward by the prevailing, upper level winds. Pulling in heat from the surrounding plains, some of these thunderstorms become supercells, producing large hail and spawning tornadoes.

Often rising to an altitude of 50,000 feet (more than three times the elevation of the Front Range peaks), they can be seen across vast distances. From our Littleton farm, we can spot the bright cloud tops of storms approaching the Nebraska, Kansas and New Mexico borders. Though dangerous for those caught in their path, these mountains of water vapor, lit by the setting sun, are among the most awe-inspiring sights in nature.

Tuesday, June 16, 2009

Miller Moth Invasion

We have arrived at our Littleton, Colorado, farm during the peak of the annual "miller moth" invasion. These army cutworm moths, move through the Front Range corridor each June, on their way to a summer in the mountains. There they enjoy milder conditions and feast on the nectar of numerous wildflowers.

By late August, the moths head back to the High Plains where they lay their eggs in weedy vegetation along streams and fence lines. The adults die as autumn progresses but the eggs hatch into caterpillars, which feed on grasses and broad-leafed weeds. Overwintering in the larval form, the caterpillars resume feeding as the weather warms and often move as "armies" across the prairie landscape. In early May, the cutworms burrow into the soil, pupate for a few weeks and emerge as adult moths.

Migrating toward the mountains, the moths travel at night and seek refuge in narrow crevices (tree bark, human structures) during the day. Attempting to resume their journey at dusk, many become trapped in homes, heightening the illusion of a moth invasion. Numbers vary from year to year, depending on the severity of the previous winter and on other factors that affect the survival of larvae. In addition to the malice of frenzied homeowners, the moths face predation by birds, bats and amphibians as they migrate to and from the high country. Since many die in the mountains and the return flight is less concentrated in time, Front Range homeowners do not experience a second invasion in late summer.

Monday, June 15, 2009

Dainty Killers

The other day, I was looking down from our deck which overlooks a flower garden. A damselfly had settled onto a rock amidst the colorful plants, its wings folded vertically above its thin torso. I soon noticed several others, perched on flower stalks or directly on the mulch.

Unlike their cousins, the dragonflies, damselflies are rather delicate insects with comparatively weak flight capabilities. As a result, they prefer to hunt by stealth, patiently waiting for small, flying insects to pass nearby. A variety of beetles, flies and other sizable insects are beyond their kill capacity so they must focus on less formidable prey. Once a potential meal is located, the damselfly springs into the air, snares the victim and returns to its perch, a behavior reminiscent of our small avian flycatchers.

Represented by many species, damselflies would be easily overlooked were it not for the bright neon coloration of the males. Like dragonflies, they mate in the air and females lay their eggs on aquatic vegetation; those that hatch (and are not eaten by fish, amphibians and herons), spend from several months to two years as aquatic larvae before enjoying their single, brief summer as aerial hunters.

Sunday, June 14, 2009

African Immigrants

While we are fascinated by the natural history of other species, humans tend to be rather provincial when it comes to our own origin and homeland. We are proud to be natives of France, Michigan or Bogota.

Current scientific evidence suggests that humans evolved in East Africa, about 125,000 years ago (just yesterday in geologic time); a minority of anthropologists believe that our species arose at several sites across Africa and southern Asia but DNA evidence seems to support the former hypothesis. It also indicates that humans did not leave Africa until 80,000 years ago, reaching Australia 60,000 years ago, Europe 40,000 years ago and North America 20,000 years ago. Hawaii was not colonized until 500 AD and humans did not reach New Zealand until 800 AD.

In our modern world, a mosaic of cultures, religions and political systems, the concept of a borderless planet seems impractical, unsustainable and, frankly, unsafe to most humans. After all, immigration has acquired a negative image, bringing to mind the clandestine invasion of desperate individuals, some by foot, others by sea. We are reluctant to accept our common origin, preferring to emphasize our superficial differences; but, in the end, we are all African immigrants.

Saturday, June 13, 2009

Evening at the Marsh

After nearly a week of muggy air and heavy rains, mild, drier weather has settled into Missouri. Taking advantage of the pleasant conditions, we headed down to our local wetland preserve last evening.

The wildlife seemed to be enjoying the weather as much as we were. Indigo buntings sang from atop the saplings, goldfinches and eastern kingbirds moved across the prairie and eastern bluebirds, aglow in the late day sun, guarded their nest boxes. The woodland border was alive with the calls and activity of numerous birds, including yellow-billed cuckoos, great crested flycatchers, eastern wood pewees, red-bellied woodpeckers, yellow warblers, northern orioles and blue-gray gnatcatchers. Closer to the water, common yellowthroats scoured the thickets, green-backed herons haunted the shallows and red-winged blackbirds sang from the cattails. The distinctive call of cricket frogs echoed across the marsh, now joined by the deep rumble of bullfrogs. Oblivious to all of this noise and activity, painted turtles lounged on half-submerged logs, slipping into the water as we approached.

As dusk settled on the wetland, common nighthawks flapped across the evening sky, barn and tree swallows made their last forays of the day, little brown bats circled above the marsh and a barred owl called from the creekside forest. Darkness brought fireflies, flashing their own affection for this spectacular June evening.

Friday, June 12, 2009

Nature from a Bench

Yesterday afternoon, after a hectic day at work, I sat on a bench outside my office, waiting for a ride to dinner. At such times, I usually settle into a passive observation mode, a detour from the stress of modern life. Though I was sitting at the edge of a campus parking lot, with little vegetation in close range, there was plenty of activity to hold my attention.

We humans, enamored with scenic landscapes, tend to ignore the natural residents of our urban settings. But a male cardinal, singing from the gate of a pickup, was just as sincere as a trogon, calling in an Arizona canyon. House sparrows, foraging in the shrubbery, were just as focused as weaver birds of the African Plains and, zooming overhead, chimney swifts expressed the same exuberance as their white-throated cousins of the Front Range foothills. At my feet, tiny ants scoured the concrete desert, gathering morsels of food with the same determination as the swarms of a tropical rainforest.

The natural world, after all, is a continuum, broken only by man-made structures. Whether on a Midwestern campus or in the wilds of Borneo, we share the same sun, the same thin atmosphere and the same struggle to survive.

Wednesday, June 10, 2009

A Puzzle of Plates

During our brief human life span and, indeed, throughout the entire course of human history, the appearance of our globe has changed very little. While ice cover has waxed and waned with the climate, the basic shape of our oceans and continents has been relatively stable. Only the intermittent earthquakes and volcanic eruptions hint of the ongoing evolution of Earth's surface.

In fact, the crust of our planet, 30 miles thick, is composed of seven large and many smaller tectonic plates, all of which are continually in motion, colliding, subducting or scraping along one another. During this process, which is powered by heat within the Earth, they drift, change shape, split apart or merge with other plates; these latter events are mediated by the opening and closing of oceans. This rifting and suturing continues today, at a rate that is too slow for us to perceive.

The East African Rift, which began to form 40 million years ago, will eventually open a seaway through the Continent; 100 million years from now, the African Ocean may separate the two segments. Perhaps the Pacific Ocean will stop forming along its southern and eastern edges and, over 200 million years, be consumed in the Aleutian and East Asian trenches; in concert, the Atlantic may continue to spread and the American Continents may approach the eastern coasts of Asia and Australia. We, of course, will never know.

Tuesday, June 9, 2009

Intertropical Convergence Zone

Last week's crash of Air France 447, over the central Atlantic, has brought the Intertropical Convergence Zone (ITCZ) into the news. Though the cause for this tragedy remains uncertain, it appears that the perpetual stormy weather of this equatorial band was not a major factor.

The ITCZ is a zone of cloudiness and thunderstorms that circles the globe, over or near the equator. The Earth's rotation produces low-level, northeast trade winds in the Northern Hemisphere and low-level, southeast trade winds in the Southern Hemisphere; these converge in the ITCZ and, in combination with solar heating, force the surface air to rise, producing extensive bands of showers and thunderstorms (the latter produce heavy rain but, devoid of upper level jet stream energy, are rarely intense). As one might expect, storms build through the day (in response to solar radiation) and dissipate overnight. Beneath the rising air, calm conditions develop at the surface (as in the eye of a hurricane) and sailors have long experienced the becalming effects of the ITCZ doldrums.

Though centered over the equator through the course of a year, the zone shifts north and south with the seasons, following the most direct rays of the sun; due to the retention of heat by rocks and soil, this shift is more pronounced over the equatorial Continents than over the oceans. Moving toward the Tropic of Cancer during the Northern Hemisphere summer, the ITCZ is the focal point of Atlantic hurricane formation, triggered primarily by upper level lows as they move westward from the coast of Africa.

Monday, June 8, 2009

Black Walnut Trees

Though in full leaf for less than three weeks, our black walnut trees already have small fruits growing at the tip of their stems. Over the next few months, these walnuts, encased in a leathery, green skin and pungent black pulp, will grow to a diameter of 2 inches and, by mid August, will begin falling to the ground.

Favoring alkaline soils, black walnuts are common across the Midwest and Northeast, concentrating in regions with limestone bedrock (such as the Missouri Ozarks and the Ohio River Valley). Large trees, often reaching 100 feet in height, they are resistant to natural pathogens and may live 250 years; unlike their close relatives, hickories and butternuts, they prefer moist lowlands.

Heavily used by eastern gray squirrels for food and shelter, the black walnut has long been exploited for both its fruit and its hard, fine-grained wood, used primarily for furniture construction. We naturalists admire its massive frame, its seasonal bounty, its distinctive fragrance and its appeal to varied wildlife species, from tent caterpillars to great horned owls.

Sunday, June 7, 2009


The most recognizable natural symbol of Australia, Uluru, also known as Ayers Rock, rises more than 1100 feet above the arid terrain of the Continent's Red Center. Composed of arkosic sandstone (rich in feldspar), this spectacular formation developed over the course of a half a billion years.

As the Precambrian gave way to the Paleozoic Era, some 600 million years ago (MYA), ancient mountains to the west and southwest of Uluru were eroding into the Amadeus Basin, producing vast alluvial fans of debris. By the Ordovician, 500 MYA, seas invaded the region, compacting these deposits beneath layers of ocean sediment. During the Silurian Period, about 400 MYA, the region underwent compression, likely related to collision with other continents, uplifting and tilting the various layers of rock. Over the past 300 million years, softer overlying and surrounding sediments have eroded away, leaving the massive Uluru monolith, almost 6 miles in circumference. As large as it is, Uluru is but the tip of a sandstone formation which extends outward and downward for several miles.

Kata Tjuta (the Olgas), 16 miles west of Uluru, formed in a similar sequence but is composed of conglomerate rock. Both formations, sacred sites for regional Aboriginal tribes, are protected within the Kata Tjuta-Uluru National Park, a World Heritage Site; the Park is about 280 miles southwest of Alice Springs.

Saturday, June 6, 2009

South Sandwich Islands

Remote, rugged and swept by icy gales, the South Sandwich Islands lie on their own microplate, in the extreme South Atlantic. Over the past 3 million years, this small tectonic plate has been rifting from the Scotia Plate, a rectangular, oceanic plate that stretches eastward from the tip of South America.

The rifting between the Scotia and Sandwich Plates is forcing the latter to the east and, as a result, it has been overriding the southern edge of the South American Plate. The subduction of the South American Plate (an ongoing process) has produced a volcanic island arc (the South Sandwich Islands) atop the Sandwich Plate. Geologists have noted the similarity of this island chain to the Lesser Antilles of the eastern Caribbean; both island arcs are at the eastern end of long, narrow tectonic plates (the Caribbean and Scotia Plates) that were likely squeezed between South America and its adjacent continental plates (North America and Antarctica) as the Atlantic opened and the American Plates moved westward.

Unlike the Lesser Antilles, the South Sandwich Islands, discovered by James Cook in 1775, do not provide idyllic settings for human habitation. Rather, they are home to huge populations of sea birds, penguins and marine mammals that feed in the rich, cold waters of the South Atlantic. Indeed, this isolated archipelago harbors one of the largest congregations of marine life on the planet, nourished by krill-laden currents from the coast of Antarctica.

Thursday, June 4, 2009

The Depth of the Sea

Oceans cover over 70% of Earth's surface and, across the globe, have an average depth of about 12,500 feet. Of course, this average reflects a wide range of underwater topography, from shallow continental shelves (averaging less than 500 feet deep) to ocean trenches (often more than 25,000 feet deep).

The Southern Ocean, though the fourth largest, actually has the greatest average depth (near 14,500 feet) while the Arctic Ocean, the smallest of our five primary bodies of water, is the shallowest, averaging about 3400 feet in depth. The Pacific Ocean, which covers a third of the globe, has an average depth of 14,000 feet, the Atlantic averages 11,000 feet and the Indian Ocean averages about 12,800 feet. The deepest areas of the sea occur in ocean trenches, where an oceanic plate is subducting beneath another tectonic plate; the Mariana Trench, just east of the Mariana Islands and Guam, plunges to a depth of 36,000 feet, the deepest point on the ocean floor. Other well known trenches (and their approximate maximum depths) include the Philippine Trench (34,600 feet), the Japan Trench (30,000 feet), the Puerto Rico Trench (28,200 feet), the Atacama Trench (26,500 feet), the Java Trench (25,400 feet) and the Aleutian Trench (25,200 feet). The Gulf of Mexico is generally shallow (40% is less than 80 feet deep) but the Sigsbee Deep, in its southwest quadrant, reaches depths of more than 14,000 feet.

Sunlight only penetrates about 400 feet below the surface of the sea. When one considers the extent and depth of our oceans, we come to realize that nearly 70% of Earth's living ecosystem (sea and land combined) lies in perpetual darkness!

Wednesday, June 3, 2009

The Nature of Blogs

Many (if not most) people tend to characterize bloggers as opinionated individuals who like to see their words in print. While there is some truth to that assessment, those who blog for these reasons alone soon lose interest and give up the commitment.

The majority of bloggers start out by creating a daily or weekly journal, focused on their special area of interest; the subject may be specific or general, including fields such as politics, science, religion, nature and philosophy. Over time, these writers sense the opportunity, through their personal enthusiasm and the structure of their blog, to encourage others to become interested in and committed to their own source of passion.

Some of us also use this forum to challenge traditional assumptions of human society, many of which, we feel, obstruct social progress and threaten the welfare of this planet. This choice may offend some readers and is likely the primary rationale for the negative sentiments of non-bloggers, mentioned above. But the blog is the ultimate form of free speech, unconstrained by editors, corporate interests and public opinion.

Tuesday, June 2, 2009

Juveniles of June

Born in April or May, many birds and mammals begin to lose their baby features by June and have assumed juvenile behaviors. Not yet fully independent, they wander further from their parents and, in the case of mammals, have developed that lanky appearance of adolescents. Young squirrels and cottontails abound in our neighborhoods while lean fox and coyote pups wander the farmlands, eventually breaking free of their family unit. Spotted fawns, kept secluded for the first weeks of life, now join their mothers on dusk shrouded meadows and young birds, as large as the harried parents, chase their providers about the forest, demanding handouts at every stop. Out in the wetlands, young geese and ducks, having entered that ugly, teenager phase, mingle with the more attractive adults.

Unlike higher primates (including humans), most wild creatures pass through childhood in a matter of months, quickly severing the parental bond; other exceptions include whales, bears and some carnivores but none come close to the slow maturation and prolonged dependence of the human child. The juveniles of June, venturing alone into the wilderness, highlight the fragility of our own species.

Monday, June 1, 2009

Cantore Season

Over the past month, Jim Cantore and his cohorts at the Weather Channel have, hopefully, been making their final preparations. Gassing up the satellite trucks, packing the overnight bags, updating their frequent flier accounts and, of course, strengthening those leg muscles, are all essential for their coming responsibilities. After all, this is the first official day of the Atlantic Hurricane Season.

In the upcoming weeks and months, these storm warriors will spread out along our Atlantic and Gulf Coasts, readjusting their positions as the hurricanes threaten land. Driving against the flow of traffic, they will gear up to stand in the wind and waves so that we, the hapless, landlocked viewers, can experience the full fury of these deadly storms. Some admire their courage; others question the message of their on site reporting; still others find their antics comical.

The season of hurricanes and their traveling stuntmen will last into early November. Hopefully, the killer storms will stay offshore and the intrepid reporters will have to settle for videos of high surf.