Thursday, July 31, 2014

Triple Play Upslope

Three days ago, as I headed west across Kansas, high pressure over the Southern Plains swept heat and humidity northward.  In concert, a low pressure system was moving eastward along the Colorado-New Mexico border, intensifying this southerly flow and directing the stream of warm, moist air toward the Front Range.  By the following afternoon, Metro Denver had temperatures in the upper 80s (F) with dew points in the 60s, reflecting humidity well above normal for this semi-arid region.

Ahead of a cold front, which was dropping south across the Great Plains, thunderstorms began to ignite, producing scattered heavy downpours along the Front Range urban corridor.  Then, overnight Tuesday into Wednesday, the front passed through Denver and a steady, easterly wind pushed the entrenched, humid air up against the foothills.  The enduring upslope kept temperatures in the 50s for the next 36 hours, unleashing bands of moderate rain and light drizzle.

Today, as the upslope dynamics break down, partly sunny skies should develop.  Nevertheless, residual moisture will feed afternoon thunderstorms, ignited by the intense Colorado sun.  Similar conditions are forecast for tomorrow but, by the weekend, the monsoon moisture will be cut off by high pressure over the region and dry, sunny weather is expected; then again, weather forecasts beyond 24 hours are of dubious value.

Wednesday, July 30, 2014

The Nature of Ebola

Ebola is a filamentous, RNA virus; of the five known species, four cause disease in humans.  Fruit bats appear to be the natural host (carrier) of ebola virus; they are unaffected by the virus but animals or humans that handle or consume bats, are bitten by them or consume fruit that they had partially eaten may become infected.  The index case in human outbreaks appears to most often result from that person having handled or consumed an infected animal (rather than having acquired the virus directly from a bat).  The virus has an affinity for endothelial cells, monocytes and hepatocytes (liver cells) where it begins to replicate; a flu-like illness generally develops within two weeks of exposure though the incubation period varies from 2 to 25 days.

The flu-like symptoms gradually worsen, leading to multi-organ failure and death in 50-90% of infected humans; coagulopathy leads to bleeding in the skin, GI tract and mucous membranes in half of the cases.  Transmission between humans, first documented in the Sudan and Congo outbreaks of 1976, is by contact with bodily fluids (saliva, blood, vomitus, stool, tears, sexual secretions, etc.); to date, transmission via respiratory droplets has not been documented.  The current ebola outbreak in West Africa is the largest documented by the World Health Organization to date and its potential spread to Nigeria via an infected traveler raises the specter of a more widespread outbreak.

At this time, there is no specific anti-viral therapy and an ebola vaccine is not yet available; supportive care (IV fluids, artificial ventilation, nutrition, blood pressure support, etc.) is currently the only medical option, placing healthcare workers at significant risk.  Prevention is the key, including education regarding contact with fruit bats, wild game and sick humans.  Since the human death rate is very high, a reservoir of infection does not develop within human populations; however, since the incubation period may be as long as 3 weeks, the disease may be spread before the infected individual is symptomatic.  An additional concern is the recent finding that male survivors of ebola may retain the virus in their semen and might infect sexual partners long after their illness subsides.

Tuesday, July 29, 2014

Harnessing the Wind in Colorado

Returning to Colorado yesterday, I was pleased to see that the new wind farm section, north of I-70 between Genoa and Arriba, has progressed significantly since my departure.  This is actually the third segment of a wind farm developed by NextEra; the entire farm extends eastward from Route 71 and lies adjacent to the Cedar Point Wind Energy Project (north of Limon and west of Route 71) operated by RES Americas.  Combined, the two farms will have 510 wind turbines along and near the High Plains escarpment in northern Lincoln County.

According to the American Wind Energy Association, Colorado ranks 10th among U.S. States in both its number of wind turbines (currently more than 1500) and the mega-watts produced; this is impressive since the State ranks 13th in potential wind energy.  Currently, wind energy accounts for 14% of electricity produced in the State, an achievement that places Colorado 6th in the nation.

Colorado is definitely ahead of the curve in its use of wind energy and is home to Vestas, a leader in wind turbine construction, as well as other wind energy companies.  On the other hand, the State is nowhere near its potential wind energy production which, according to experts in the field, would yield 24 times the current annual electricity consumption in the State; better yet, this energy will be generated without carbon emissions or water use.

Monday, July 28, 2014

A Hundred Years of War

One hundred years ago today, World War I began; though far from the first war in human history, it might be viewed as the beginning of modern warfare.  The Great War was followed by World War II, the Korean War, Vietnam, the Iraq-Afghanistan War and ongoing conflict throughout the Middle East, not to mention a host of genocidal and civil wars in the Balkans, Africa, Asia and Central America.

Many humans believe that war is often justified, pointing to the World Wars as examples; however, one can argue that those multinational conflicts and their massive death tolls (of soldiers and civilians) could have been prevented if early action had been taken to isolate the perpetrators.  Surely, subsequent wars might have been avoided by more aggressive negotiation, more reliable intelligence and a multinational commitment to economic sanctions.  It seems to me that terrorism would have been more effectively combated by limited strikes, shared intelligence and economic pressure on countries that support their activity; as it turned out, regional wars have served to fuel the spread of terrorism across the globe.

Military solutions, while temporarily effective in some cases, rarely lead to lasting peace, exact a heavy toll on innocent civilians and introduce the risk of failed states.  Most agree that the current conflicts in Ukraine and Gaza will only be settled through negotiation; unfortunately, countries in a position to exert pressure on the combatants are influenced by their own political and economic forces, diminishing both their willingness to impose sanctions and their effectiveness as mediators.

Saturday, July 26, 2014

Missouri's Pinnacles

Silver Fork Creek rises on the Glaciated Plain of north-central Missouri, a few miles southwest of Centralia; snaking southwestward, this stream eventually enters Perche Creek, a large tributary of the Missouri River.  About 14 miles north of Columbia, a loop in the course of Silver Fork Creek, combined with erosion along Kelley Creek, one of its tributaries, has produced a narrow ridge of limestone, known locally as The Pinnacles.

Mississippian in age, the limestone has weathered into irregular knobs and ledges, broken by steep ravines; at two sites, natural windows have opened in the rock wall.  Narrow foot-trails lead onto the scenic ridge, offering spectacular views of the creek and the wooded bluffs along its course.  Turkey vultures soar overhead and prairie lizards bask on the exposed limestone; deciduous forest cloaks the lower slopes of the ridge while eastern red cedars cling to the sheer rock cliffs.

Access to these scenic rock formations is on the east side of U.S. 63, about 15 miles north of Interstate 70.  Turn right (east) on Pinnacles Road, taking an immediate right at the "T."  Drive just over half a mile and enter the Pinnacles Youth Camp which is open to visitors.  The Pinnacles are just across Silver Fork Creek from the parking area but a short walk downstream is necessary to cross the creek (water conditions permitting) and to access the Pinnacles trail.  Caution on the steep, narrow ridge is strongly advised and the climb is not safe for frail adults or young children.

Friday, July 25, 2014

The Vanguard of Autumn

A few weeks after the summer solstice, some shorebird species begin to depart their Arctic breeding grounds.  Over the following weeks and months, migrant shorebirds appear in the American Heartland, stopping to rest and feed on their way to southern beaches.

This annual "autumn" migration begins by mid July and will peak from late August through mid September; some shorebirds (e.g. yellowlegs, dunlins) may be encountered as late as October and early November.  These travelers are best observed at our larger lakes and reservoirs, where the plovers, sandpipers, avocets, godwits and phalaropes gather in the shallows or forage across the mudflats; backwater areas are generally most productive but shorebirds may also be seen in ephemeral ponds or on flooded fields.

While many species are easily identified, the smaller sandpipers pose a challenge for most birders and patient observation with a spotting scope is often necessary, especially since these skittish migrants must usually be viewed from a significant distance.  Some of us, more focused on this vanguard of autumn than on the individual travelers, welcome their presence as a sign that the intense heat of summer will soon begin to wane.

Thursday, July 24, 2014

Weather from Above

While perusing Sitka Nature, I learned of the website Earth, which provides an animated global image of surface wind patterns over which other weather parameters (temperature, humidity, ocean currents) can be superimposed.

While there are many interactive weather maps available on the Internet, this image is especially fascinating.  Most importantly, one can easily visualize how surface winds are produced by areas of high and low pressure, watching as winds flow from the former to the latter.  The Intertropical Convergence Zone (see this post)  is also easily identified and tropical storms, hurricanes and typhoons stand out as tight spirals (counterclockwise in the Northern Hemisphere, clockwise in the Southern) against the calmer ocean background.  Under the right conditions, upsloping winds are observed along mountain ranges, cooling the regional temperature and dropping their cargo of rain or snow.

Anyone interested in global weather patterns is strongly advised to check out this site; clicking on the label "earth" opens a menu of data that may be superimposed on the wind patterns and users can zoom into areas of interest across the globe.  Weather junkies, like myself, may find themselves mesmerized for hours at a time.

Wednesday, July 23, 2014

The Dead of Summer

We humans, tropical beings that we are, often refer to "the dead of winter," when frigid air and bitter winds seem to bring life to a standstill.  Of course, this does not actually occur and, if we have the gumption to venture outdoors, we find that many species of wildlife remain active under such conditions; indeed, their very survival depends on that hunting and foraging activity.

In mid summer, especially in the American Midwest, similar periods occur when oppressive heat and humidity discourage mid-day activity by humans and wildlife alike; only the insects (and perhaps some reptiles) thrive in such conditions.  In contrast to the dead of winter, this dead of summer truly affects a wide range of animals, causing them to limit their activities to the early morning and late day hours.

Fortunately, these periods of oppressive heat tend to be relatively brief and are soon swept away by Pacific storm systems or deported by angelic incursions of Canadian air.  The last few days, with afternoon highs in the 90s (F) and dew points in the 70s, brought the dead of summer to central Missouri but the next cold front is now approaching from the northwest; cooler and drier air behind the front will (at least temporarily) rejuvenate the region.

Tuesday, July 22, 2014

The Nature of Ukraine

A series of tragic events have kept Ukraine in the news over the past year.  It thus seems appropriate to balance this image with a look at the natural features of that country, the largest that lies totally within Europe.

The great majority of Ukraine is covered by fertile plains, steppes and low plateaus.  Exceptions include the Carpathian Mountains, that cut across the southwestern corner of the country, and a swath of low, wooded hills along its northern border, extending southward from Belarus.  The Dneiper River, the fourth longest in Europe, rises in western Russia and flows southward through Belarus and Ukraine to the Black Sea; half of its length (about 670 miles) snakes through the center of Ukraine, passing through Kiev and several large reservoirs as it bisects the country.  Other Ukrainian rivers also flow north to south, entering the Black Sea.  As we know, the Crimean Peninsula was annexed by Russia earlier this year.

The rich soil of the Ukrainian plains yields one of the largest wheat crops on our planet, the Carpathian Mountains are home to brown bears, wolves and lynx and the varied geologic strata of Ukraine harbor a wealth of minerals, including large deposits of sulfur, manganese and iron ore.  Of the many National Parks and nature preserves that lace the country, four are UNESCO Biosphere Reserves.  Clearly, Ukraine is more than a theater for political and military conflict.

Monday, July 21, 2014

Reducing Personal Consumption

Those of us who care about the welfare of natural ecosystems lend our support in a number of ways.  Most donate funds to local or national conservation organizations, such as those listed on this blog.  Many of us also engage in volunteer work at nature preserves or participate in environmental restoration projects.  Almost everyone is attentive to recycling efforts, especially to those facilitated by our communities.

But the most effective way in which we can contribute to the conservation of our natural resources is to reduce our personal consumption.  Limiting purchases to what we truly need, buying used products (including homes, vehicles, tools etc.) and buying items made from recycled materials all help to reduce the destruction and degradation of natural ecosystems.  Of course, efforts to reduce our use of fuel, electrical power and fresh water are also important; the purchase of food and other necessities from local producers and a commitment to the use of mass transit will both help in this regard.  Finally, human population control is essential to reducing the worldwide consumption of natural resources.

Too often, we are discouraged by the overwhelming power of industry, convinced that our behavior will have little impact on the war against nature that unfolds across this planet.  But, beyond the donations that we make and the votes that we cast, we must reduce our personal consumption and, in the process, encourage others to do the same.  Eventually, retailers and producers will respond, the maldistribution of goods and services will be corrected and the assault on natural ecosystems will end.

Sunday, July 20, 2014

The Fallibility of Science

Those who attempt to derail science, for whatever reason, point to its long history of false conclusions.  The scientific method, after all, is a trial and error process, based on theories that must be proved or disproved through rigorous testing, evidence gathering and experimentation.

Errors are common in all scientific disciplines.  New medications or therapeutic procedures are withdrawn due to ineffectiveness or unexpected side effects, industrial products are recalled due to defective parts or safety concerns, the projected paths of hurricanes are altered and a host of theories are abandoned due to lack of confirmation; in all cases, the setbacks serve as guides for adjustment and further testing.  In its continual search for truth, science hits many roadblocks and heads down many blind alleys but such failures add to our knowledge base and stimulate our imagination; indeed, they are vital to scientific progress.

Yet, science agnostics latch onto these failures, using them to ridicule the scientific method and to support non-scientific dogma based on faith or political expediency.  They prefer simple, convenient answers to the mysteries of nature and their sources are deemed to be infallible; scientific knowledge is their enemy.

Friday, July 18, 2014

Lawns & Water

Finding themselves in the midst of a prolonged, severe drought, it was heartening to learn that California water authorities had the fortitude to enact harsh water-use restrictions; according to national news services, they have admonished homeowners "not to overwater their lawns" and threatened possible fines if water is seen on their driveway or sidewalks.  Really?  Is this the best they can do in a water emergency?

In my opinion, anyone who lives in the arid and semiarid regions of the Western U.S. has no business watering their lawn (ever!).  In fact, I see no need to water lawns anywhere in the U.S.; those who live in central and eastern portions of the country generally receive enough annual precipitation to nourish grass and, when periods of drought occur, brown lawns are hardly a threat to society.  Unfortunately, those Americans enamored with massive lawns are the citizens most likely to use automated sprinklers to douse their prized carpets (often as rain is pouring from the sky).

Receptive to the ads of the lawn masters and sensing pressure from their neighbors, Americans ignore the relative scarcity of clean, fresh water on this planet and use far to much of it to produce thick, green lawns.  The latter, of course, are not natural habitats; from the point of view of most wildlife, they might as well be parking lots (see Lose Some Lawn, The Cost of Lawns and Man and his Lawn).

Thursday, July 17, 2014

Front Range Geology

During the Cretaceous Period, 135 to 65 million years ago (MYA), a shallow sea stretched from the Texas Gulf Coast to British Columbia, covering much of Colorado; deposits within and along this sea would yield the Dakota sandstone and Pierre shale that are now evident near the base of the Front Range and across the Colorado Piedmont.  Near the end of the Period, a layer cake of horizontal Mesozoic and Paleozoic sediments stretched above the deep Precambrian basement rock (youngest to oldest from top to bottom).

Then, about 70 MYA, the Laramide Orogeny began and the Front Range of the Rockies crumpled skyward, reinforced by a second uplift during the Miocene Period, some 25 MYA.  The overlying strata were tilted upward, toward the crest of the range, and erosion began to sculpt the layers; resistant sheets of sandstone produced fins and ridges while intervening, softer layers of shale eroded into valleys.  Meanwhile, Tertiary debris, eroded from the Front Range, was carried eastward by many streams and rivers that dropped from the mountains and meandered across the High Plains; as a result, a veneer of these younger deposits covered the Cretaceous shale and sandstones left behind by the retreating sea.

Today, driving westward toward the Front Range, one crosses the Tertiary landscape of the High Plains, broken by valleys of Pierre shale and Cretaceous sandstones along the South Platte River and its tributaries.  At the foot of the Rockies, one encounters the Dakota hogback (Cretaceous sandstone), backed by the Morrison Formation, a valley of Jurassic shale; both are rich in dinosaur fossils.  West of the Morrison valley is an outcrop of Permian sandstone (the yellow-gray Lyons Formation) and, up against the foothills, are the salmon-colored sandstone fins of the Fountain Formation (Pennsylvanian in age).  The foothills and mountains are uplifts of ancient Precambrian granite, laced with Tertiary and Quaternary debris along their many streams.  In effect, the traveler crosses progressively older rock strata from the High Plains to the Front Range.

Wednesday, July 16, 2014

Autumn in July

An atmospheric trough, produced by a dip in the jet stream, has ushered cool, dry Canadian air into the American Heartland; overnight lows have fallen into the low 50s (F) while afternoon highs are topping out in the 70s.

This mid summer gift, arriving on the heels of hot, muggy weather, will certainly invigorate both the wildlife and those humans who enjoy watching them.  At Forum Nature Area, here in Columbia, birdsong has noticeably recovered from its summer suppression and visitors are unusually numerous for mid July.  Back home, many of our permanent avian residents are checking out the feeder (which I generally fill from October to April), seemingly fooled by the unseasonable chill.

No doubt, those who reject the evidence of global warming will point to this cool air incursion as further support for their entrenched position.  However, if they bothered to check the weather map, they would find that the trough is bounded by atmospheric ridges, bringing warmer than average conditions to the Pacific Northwest and Northeastern U.S; along the borders of the trough, thunderstorms delineate the clash of the air masses, producing some flooding in the East but bringing much needed rain to the Southern Plains.  Indeed, the undulating jet stream, rather unusual in mid summer, may be (at least in part) a consequence of our warming global climate.  Regardless of the cause, we'll enjoy the autumn-like weather while it lasts.

Tuesday, July 15, 2014

America's Greatest Health Problem

What is the greatest health problem in the U.S.?  If you watch television you might conclude that it is erectile dysfunction, testosterone deficiency or postmenopausal vaginal dryness; after all, medications for those maladies are heavily advertised on prime-time programming, including the evening news.

Looking at statistics, others might suggest that our greatest health problem is heart disease, cancer, diabetes or some other common American disorder.  But, in my opinion, our most pressing health issue relates to preventive care, specifically to the lack of attention that it receives among the general population.  While those with insurance might show up for their annual physical (a practice of questionable value in young, healthy adults), too many Americans ignore recommendations related to diet, exercise, smoking, alcohol consumption, illicit drug use, seat belt use and other lifestyle choices.  Among the reasons for this deficiency is the conviction that modern American medicine will bail them out with wonder drugs, invasive procedures, screening tests and the latest surgical techniques.

Unfortunately, this unbridled faith in American medicine is misplaced.  Despite our expensive, high-tech healthcare system, America does not rank in the top 50 countries when it comes to longevity.  This sad fact reflects both the lack of adequate healthcare services for impoverished citizens and the sedentary lifestyle of most Americans, reflected by the high rate of obesity and its numerous sequelae.  Americans should rely on their healthcare provider for guidance but their personal health will depend primarily on the lifestyle choices that they make.

Monday, July 14, 2014

Mississippi Kites over Columbia

For the past several days, a pair of Mississippi kites have appeared above our neighborhood in Columbia, Missouri.  Generally present during the morning and evening hours, these graceful, aerial hunters have been observed in the company of chimney swifts and common nighthawks, feasting on clouds of insects.

Perhaps they drifted north with the warm, humid air that arrived this week or they may be nesting in the area.  Though I have observed them in central Missouri in the past, I have never enjoyed their presence for an extended period of time nor have I observed them at such close range, strafing the treetops of our property in search of prey.

As veteran birders know, sightings of uncommon species often occur unexpectedly; indeed, such encounters account for a significant percentage of additions to our life list.  Of course, even chance sightings depend on active observation, whether they occur in our neighborhood, at local nature preserves or at wildlife refuges far from home.  Awareness of nature is not achieved through passive means.

Sunday, July 13, 2014

American Lotus

Hiking around a lake south of Columbia, my wife and I found that the circular leaves and pale yellow flowers of American lotus had taken over one of its shallow coves.  This emergent aquatic wildflower, while resembling water lilies, belongs to a separate genus; it is native to North America and found in most States east of the Rockies and in California.

Favoring shallow ponds and lake margins, the American lotus spreads by seed or rhizomes and can rapidly take over an area of calm water.  Thick tubers develop at the base of the plant and both the flower and the leaves form at the end of long, individual stalks.  The large flowers (which appear from June to September in Missouri) are composed of twenty or more petals and have a large, central seed pod that resembles a shower head; while the showy, cream-colored flowers bloom for only two days, the seed head gradually matures, eventually releasing large seeds that are consumed by waterfowl and humans.  The tender vegetation may also be cooked and eaten and the starchy tubers have long been consumed by Native Americans; beaver and muskrat are known to feed on the rhizomes and the vast "stands" of American lotus offer ideal habitat for a wide variety of aquatic invertebrates, fish, amphibians, reptiles and mammals.

The seeds of American lotus, known as alligator corn in the Southeast, remain viable for at least 200 years.  In areas where swamps were once drained for agriculture or development, flooding or habitat restoration may reawaken the long dormant plant; it is thus not surprising that ancient civilizations believed the lotus had mystical powers.

Saturday, July 12, 2014

First Annual Cicadas

As warm, muggy air pushed back into Missouri, I heard the first annual cicadas in our shade trees last evening.  After several years underground, where they feed from the root of a tree or shrub, the nymphs emerge by mid summer, climb a tree and molt into the adult form.

Focused solely on breeding, the adults may live for a few weeks if not consumed by a predator (jays, crows and house cats, among others).  During that time, the male attracts females with a loud, buzzy call that builds to a crescendo; these calls, often delivered in unison and especially prominent on mid-late summer evenings, may be heard into September.  Females dig a shallow groove in the tender, terminal limb of a tree or shrub and deposit their eggs within those tracks; this practice often kills the limb and clumps of dead leaves soon speckle the summer woodlands.

Once they hatch, newborn nymphs drop to the ground and burrow into the soil, not to emerge for several years.  Their entry and emergence burrows aerate the soil and the nymphs themselves are potential prey for mice, shrews and moles.  How vital cicadas are to woodland ecosystems is a subject for debate but their prolific breeding, so evident on summer evenings, has ensured their survival in nature's realm.

Friday, July 11, 2014

Our Crustacean Farm

Three months ago, we established a compost pile in our Columbia, Missouri, yard (see Building a Compost Bin).  Since that time, the grass clippings, dead leaves, sawdust and kitchen leftovers (fruits, eggshells and vegetables) have decayed into a darkening mound of maturing compost, fueled by the heat and humidity of a Midwestern summer.

Feasting on the organic matter and facilitating the process of decomposition is an army of insects, including ants, fruit flies and various beetles; of course, earthworms are doing their part from within the pile.  But the most numerous and conspicuous residents of the compost bin are pill bugs, those prolific Backyard Crustaceans known to children as rollie pollies.  Relying on gills for respiration and consuming a diet of carrion and rotting vegetation, they thrive in the warm, moist confines of the bin; indeed, peering into the structure, a novice might assume that it was designed to raise pill bugs.

Unfortunately, there is not a lucrative market for these ubiquitous crustaceans; in fact, the internet is loaded with advice on how to keep them out of your garden and basement.  While they may do limited damage to ground-spreading plants such as strawberries or melons, pill bugs are, for the most part, beneficial creatures, recycling organic material and enriching the soil.  They are certainly welcome in the compost bin!

Thursday, July 10, 2014

Our Evening Pewee

On the past few evenings, an eastern wood pewee has appeared in our central Missouri yard, drawn to a dead snag on an aging tuliptree.  This rather nondescript, medium-sized flycatcher is a common summer resident across the eastern U.S., where it is best observed in open woodlands, along forest margins or in riparian groves.

Hunting from the end of a dead branch, eastern wood pewees make frequent sorties, flying out to snare an insect and then returning to its perch.  This characteristic activity, combined with the flycatcher's distinctive "pee-a-wee" call, make identification easy despite its many similar (though less common) cousins.

Current evidence suggests that eastern wood pewees are monogamous and share feeding duties; a cup-shaped nest, covered with lichens, is placed in the mid canopy of a deciduous tree and 2-4 eggs are generally produced.  By late summer, the parents and their offspring migrate independently, heading for the forests and woodlands of northern South America where they winter alone.

Wednesday, July 9, 2014

At Nature's Mercy

Arriving back in Columbia Monday evening, we found ourselves enveloped in soupy, tropical air; it seemed we had taken a wrong turn on our way back from Colorado and had ended up in the Amazon Basin.  Later that night, lightning flashed along the western horizon, promising the relief of thunderstorms and, in their wake, cooler and drier air.

Within an hour of going to bed, I was awakened by fierce winds, whipping the trees in our neighborhood and lashing the windows with torrents of rain.  As the lightning and thunder became more intense, a loud roar passed overhead, as if a jet had taken off to our southwest and was climbing toward the northeast.  Checking the alarm clock, I found that our power was out and it has remained so for the past 36 hours; indeed, we anticipate another 24-36 hours before electric service is restored.

On the morning after the storm (declared a severe thunderstorm by the weather service but likely involving a weak tornado in my opinion), tree limbs and massive trunks, lay across roads, lawns and roofs; fortunately, damage was relatively minor and no serious injuries were reported.  Nevertheless, we have been "inconvenienced" by nature's wrath, learning to live without air conditioning, hot water, refrigeration, the internet and cable TV for several days; in a way, the storm has brought a refreshing change to our lives.

Friday, July 4, 2014

Geology of Rio's Domes

Watching coverage of the World Cup, one is struck by the spectacular natural setting of Rio de Janeiro, Brazil, hemmed in and partly bisected by massive domes of rock.  The most famous of these, Sugarloaf Mountain, rises at the end of a peninsula while Corcovado, the highest summit (2300 feet) creates a magnificent backdrop for the city.

All of these rounded summits are composed of Precambrian gneiss, which formed about 570 million years ago (MYA), 150 million years before life first left the sea.  Since that time, tectonic forces have lifted this ancient bedrock and both faulting and erosion have produced the scenic landscape that we observe today.  Much of that sculpting occurred in the Permian Period (some 275 MYA), when South America collided with Africa (as Pangea formed), and during the Cretaceous Period (about 100 MYA), as the South Atlantic opened and the two Continents rifted apart.

We humans, having walked the Earth for less than 130,000 years ago, finally colonized this spectacular coastline about 18,000 years ago.  Now, through the marvels of modern technology, we view its natural beauty from homes and pubs across the globe, watching as the lofty domes of ancient rock reflect the setting sun.

Thursday, July 3, 2014

The Peaceful Nature of Doves

Throughout recorded human history, doves have often been chosen as images of peace.  After all, most doves are mild-mannered birds that avoid conflict with other species.

However, as Eurasian collared doves have spread across the U.S. (see March of the Collared Dove), there has been some concern that they might threaten the welfare of native dove species, especially the beloved and widespread mourning dove.  Larger, hardier and somewhat more aggressive than most North American doves, the collared doves have adapted to a wide variety of habitats across our Continent, from the subtropics of Florida to Western desert grasslands.

Collared doves first appeared on our Littleton, Colorado, farm in 2008 and at least one pair has inhabited our property ever since.  Easily distinguished from mourning doves by their distinctive call, larger size and paler plumage, the immigrants seem to get along well with their smaller cousins and I have not noticed any reduction in the mourning dove population; indeed, at least on our property, the latter remain far more common.  If only humans would learn from these doves and welcome immigrants with benevolence and peaceful coexistence.

Wednesday, July 2, 2014

Arthur and the Trough

Last evening, as Tropical Storm Arthur churned off the east coast of Florida, a broad dip in the jet stream, known as an atmospheric trough, stretched from the Southern Rockies to the Lower Mississippi Valley and thence northeastward across the Appalachian Plateau.  Along its leading edge, cold air was knifing beneath warm, humid air to its south and east, igniting a long chain of thunderstorms.

The cold front and thunderstorms will push into the Mid-Atlantic and Northeastern States today and, ahead of the trough, southerly winds will begin to nudge Arthur to the north.  The advance of the cold front will eventually determine the path of Arthur, which is forecast to become a hurricane by tomorrow afternoon; should the front stall east of the Appalachians, the storm might rake the Atlantic Seaboard while, if it continues to push eastward, Arthur will stay well offshore.

The current forecast indicates that Hurricane Arthur will likely cross the Outer Banks of North Carolina and, farther north, lash Cape Cod and the Canadian Maritimes.  However, depending on its exact path, the storm may impact most of the Atlantic Coast, sending in high waves, producing rip currents and eroding beaches.  On the positive side, Arthur is expected to move rapidly to the northeast and, if so, its effects will be short-lived for any given location.

Tuesday, July 1, 2014

Floating the South Platte

Among the wide variety of outdoor activities that are available in and near Metro Denver is the opportunity to float the South Platte River.  Yesterday, granted another warm, sunny day along the Front Range, my wife and I pulled our our inflatable raft and enjoyed a winding, two mile excursion through South Platte Park.

Launching at C-470, below Chatfield Reservoir, we floated northward through the Park.  While we had to negotiate a number of rapids and narrow cascades,  most of our journey was a slow, peaceful drift, hemmed in by riverside marshes and woodlands.  Female mallards and common mergansers ushered their broods across the calm segments, belted kingfishers, black-crowned night herons and double-crested cormorants flew overhead, red-winged blackbirds called from the reeds, killdeer and spotted sandpipers foraged on the sandbars and yellow warblers flashed among the cottonwoods.

Floating trips offer a unique perspective of riverine ecosystems and give one an intimate appreciation for the force of moving water.  Regardless of one's skill (and ours is modest), the floater finds himself at the mercy of the river and must respect its power; patience, common sense and proper gear (including flotation vests) are always in order.