Sunday, August 31, 2008

Summer Doldrums

A visit to the Forum Nature Area this morning was a study in late summer doldrums. Following a coolish night, a heavy dew coated the vegetation and, despite brilliant sunshine, there was little wildlife activity. Goldenrod, blazing star, thistle and other late summer wildflowers adorned the prairie with purple and gold but the greenery has begun to fade and the placid shallows had a soupy, stagnant appearance.

Cicadas were warming up in the morning sun and the occasional horsefly buzzed our heads but the refuge was otherwise noticeably quiet. Indigo buntings, yellow-billed cuckoos and eastern kingbirds moved among the trees and shrubs but the distant chatter of a kingfisher was the only bird call to be heard. Even the frogs, peering from the shallows, were silent.

A couple more hot days are expected before a cold front brings another respite from the summer heat. Rain and cooler weather will surely reinvigorate the refuge and the surge of the autumn migration will soon diversify its residents. Ever-changing seasons are the best natural feature of the American Midwest.

Saturday, August 30, 2008

Ahead of the Chill

Among the last of our summer residents to arrive, common nighthawks are also among the first to leave. Dependent solely on flying insects for nutrition, they take no chances will our fickle Midwest weather and begin drifting south by late August; unlike other nightjars that winter in the southern U.S. or Mexico, common nighthawks make the round trip journey to South America each year.

Easily identified by their long, bent wings, large white wing patches, halting flight and sharp "peent" call, they are frequently seen hunting for insects over our cities and towns; despite their name, they may be active at any time of day, especially after heavy rains send swarms of insects into the air. In late spring, they nest on the ground (in open woodlands) or on flat roofs in urban areas, generally raising a pair of youngsters.

It is during their late summer migration, which peaks from late August into mid September, that common nighthawks are most numerous; large, scattered flocks, circling toward the south, are often observed on calm evenings.

Friday, August 29, 2008

Gust Front

As a potent cold front pushed toward mid Missouri last evening, an arc of thunderstorms developed, moving southeastward at 30 mph or more. Ten minutes before the storms arrived, Columbia received a blast of wind that shook the trees, downing limbs and power lines. Local meteorologists reported wind gusts of 60-70 mph.

These destructive winds, which form a gust front, result from rain-cooled air which plummets through the thunderstorms and is deflected outward as it hits the ground. In isolated storms, this outflow boundary moves out in all directions, creating a circle of gusty winds around the thunderstorm. When storms are aligned on a front, as occurred last evening, the winds move out in advance of the storm wedge, their speed a sum of the downdraft and the movement of the storms themselves.

Outflow boundaries that move into the warm sector (ahead of the front) often ignite other thunderstorms as the cool air of the gust front undercuts and lifts this moist, unstable air. As a result, a line of scattered storms begins to develop ahead of the primary cold front.

Thursday, August 28, 2008

Summer Revival

Though the college students are back in town and football starts this weekend, summer is not done with mid Missouri. High pressure, building in behind the remnants of Fay, has drifted to the Southeast and is sweeping warm, moist air into the Heartland. After almost a week of cool, autumn-like conditions, it feels like summer again and our low this morning climbed from the recent fifties to the upper sixties.

This summer revival won't last long as the next cold front is already dropping across the northern Plains. Thunderstorms are forecast to arrive by this afternoon and, behind them, cooler, drier air will settle in once again. This see-saw of summer and fall will likely continue into early October; by then, the jet stream will drift to the south and summer will be displaced to the Gulf Coast. Like early spring, late summer is caught between seasons and their clash can be stormy; but this is the gateway to autumn and, for many of us, that's enough to sing its praises.

Wednesday, August 27, 2008

The Political Taboo

As this political year continues to heat up, we will come to realize that Americans are willing to overlook many human frailties. A past history of divorce, marital infidelity, sexual indiscretions or substance abuse may not derail a candidate. Accusations of racism or sexism may be a news topic for a day or two but, in the end, will not have much effect. Open-minded Americans will consider the arguments of pacifists, war hawks, staunch capitalists, socialists, traditionalists and reformers. At least on the surface, race, gender and sexual orientation are not important factors.

But, in this free, educated, modern society, a candidate who is honest enough to profess his or her agnosticism will soon be out of the race. Americans are proud of their relationship with God. As many espouse, we are a Christian Nation.....God's Nation. His name is on our currency and in our law books. It adorns barns, front yards, bumpers and overpasses. It is invoked by ministers, athletes, criminals and politicians. To deny the Christian image of God is just plain Un-American!

America protects our freedom of religion but not our freedom from religion. We have not yet evolved to that point.

Tuesday, August 26, 2008

The Buckeye Trail

Initially proposed as a trail from Lake Erie to the Ohio River, the Buckeye Trail loops through Ohio, connecting the varied geophysical regions of the State. The 1445 mile route, which combines nature trails, abandoned rail beds and country roads, is maintained by the Buckeye Trail Association, founded in 1959.

In northeast Ohio, the Trail cuts through Cuyahoga Valley National Park and spurs out to Mentor Marsh and the Headlands Dunes on the shore of Lake Erie. Winding south across the Appalachian Plateau, the route, blazed with blue rectangles, enters the scenic Blackhand Sandstone region of the State; there it negotiates the gorges and waterfalls of Hocking Hills State Park and Tar Hollow State Forest.

Heading west, the Buckeye Trail drops from the Plateau at Fort Hill State Memorial and snakes across the Central Lowlands of the Midwest. Following branches of the Little Miami River and skirting large reservoirs, the Trail makes its way through southwest Ohio and heads north across the flat, till plains. There it picks up the abandoned towpath of the Miami-Erie Canal, which it follows to the Maumee River Parks, southwest of Toledo. Finally, the northern section of the Buckeye Trail leads across the Lake Plains of Ohio, from the remnant dunes of Oak Openings to the Emerald Necklace of Greater Cleveland.

Monday, August 25, 2008

Fay's Death Benefit

After meandering around Florida for the past week, Tropical Storm Fay, now a Tropical Depression, is about to be swept off her feet. A cold front, approaching from the northwest, will push her deep, tropical moisture into the Southeast and Mid-Atlantic States, putting a sizable dent in the severe, prolonged drought of that region. As Fay dies, a renewal will begin.

Like a mad woman with a sizable estate, Fay wreaked havoc during her restless life in Florida but will leave a wonderful death benefit to those she never knew. Many will remember her as an aimless, destructive monster, others as a kind and generous stranger. Mother nature can be both....often at the same time!

Sunday, August 24, 2008

A View of Katahdin

Yesterday, our flight from Newfoundland took us just north of Cape Breton, Nova Scotia and over the northern tip of Prince Edward Island. Leaving the Gulf of St. Lawrence, we passed above the flat, quilted lands of New Brunswick; Grand Lake appeared to the south and it was easy to follow the St. John River as it snaked westward and then northward near the eastern border of Maine.

Beyond the river, the farmlands gave way to the vast North Woods, dotted with numerous glacial lakes. Then, Mt. Katahdin appeared in this sea of green, its summit rising above the wild lands of northern Maine. Reaching an elevation of 5268 feet, it surely commands a spectacular view, a fact I hope to confirm myself some day!

Mountains, especially those isolated peaks that tower above the surrounding landscape, have always stirred my soul. Literally and figuratively, they represent the pure, high ground of our planet, a vital source of both water and inspiration.

Saturday, August 23, 2008

The Postcard Province

My wife and I flew out of St. John's this morning after a week on the magnificent island of Newfoundland. It is truly impossible to relate the wealth of spectacular scenery across that Province; indeed, as we often expressed to one another, every turn in the road was another picture postcard!

The combination of rugged, glacial terrain, expansive waterscapes and unspoiled wilderness produced an endless variety of breathtaking vistas. Newfoundland is easily the most scenic region that we have visited and we took twice as many photos as we have on any other vacation; we would have taken more but the locals, apparently victims of scenery fatigue, provide few pull-offs along the winding, back-country roads.

Our visit, of course, was all too brief. Though we managed to hit the more famous highlights, some of which are described in recent blogs, there were whole sections of the island that we could not explore; a second visit is high on our priority list. As is often the case, some of the less publicized trails and locations were among our favorites; these included the coastal trails at Salvage (near Terra Nova National Park) and the Old Man Lighthouse Trail at Trout River, just south of Gros Morne National Park.

Friday, August 22, 2008

The Gannets of Bird Rock

Cape St. Mary's juts into the Atlantic at the southwest corner of Newfoundland's Avalon Peninsula. Home to the second largest colony of northern gannets in North America, the tip of the Cape is now protected within Cape St. Mary's Ecological Preserve.

The gannet colony, which numbers 24,000 adults and half as many chicks, occupies Bird Rock and the adjacent cliffs, which plummet 330 feet from a rolling grassland to the turbulent waters of the Atlantic. Once declining due to overfishing and direct hunting, the gannet population has been rebounding over the past decade and is closing in on the Continent's largest colony, located on Canada's Gaspe Peninsula. Large colonies of murres (common, thick-billed, razorbacks) and black-legged kittiwakes also nest at the preserve and birders have the chance to see greater cormorants, great black-backed gulls and other sea birds here.

My wife and I arrived at the Cape early in the morning, greeted by sunshine with an occasional wave of sea fog. After a brief tour of the Nature Center and a helpful chat with the naturalist, we set out on the 1-mile trail to Bird Rock, enjoying the changing view of sea cliffs along the way. Silence, broken only by the wind and the lighthouse fog horn, gradually gave way to the cacophony of gannets, which covered the top and sides of the sea stack and circled above it in a massive flock. Smaller and less conspicuous colonies of murres and kittiwakes occupied the adjacent cliffs (as did more gannets) and small groups of all species were constantly moving to and from the colony, attending to the needs of their growing youngsters.

The trail ends just short of Bird Rock, leaving the visitor just meters from the raucous colony; if this is not the most accessible spectacle of bird life on the planet, I have yet to see it. Cape St. Mary's gannets begin to assemble in late March, start to nest in May and begin to disperse to wintering areas (primarily at sea) by mid September; come late October, Bird Rock will be abandoned to the wind and the waves.

Water World

The magnificent landscape of Newfoundland has been molded by water and ice and, across its varied topography, waterscapes are ever present in the form of bays, sounds, lakes, rivers and bogs. But it is along the northeastern edge of the island that water most completely dominates the geography.

North of Gander, a network of peninsulas, causeways and islands extend into the Atlantic, creating a maze of inlets, bays and waterways. We spent a day in the Twilingate area, famous for its access to "iceberg alley." After calving from the Greenland glaciers, these massive bergs float southward along the Labrador and Newfoundland coasts and are generally present from March through June. Though our visit was too late for iceberg viewing, we took a boat trip from the natural harbor into the ocean waters, passing rock islands where gulls congregated in large, mixed flocks. Black guillemots also fished along the islands and we observed eight humpbacks and a lone fin whale.

The view from Twilingate's lighthouse (northeast of town) was spectacular and increased our appreciation of the region's landscape. As an added bonus, we were treated to a unique view of several whales that fed below our vantage point, their movements easily followed in the clear, calm sea.

Tuesday, August 19, 2008

A Piece of Arizona

On this water-logged island, adorned with numerous bays, lakes and bogs, it was a shock to encounter an isolated region of desert-like terrain. But the Tablelands, in the southern part of Gros Morne National Park, look like they belong in Arizona.

About 500 million years ago, the closure of an ancient ocean put the North American and Eurasian Plates on a collision course; while most of the ocean floor subducted beneath the Continents, a slab of ocean crust was pushed over the edge of North America. As the collision progressed, this edge was crumpled into a mountain range, now represented by the Northern Appalachians (the northern end of which rise along the northwest coast of Newfoundland). The oceanic crust segment was incorporated into this range and, after eons of erosion by streams and glaciers, has been sculpted into the Tablelands of Gros Morne.

Today, this flat-topped ridge has the look of a desert mesa. Despite the abundant rain and snow, the slab of perioditite (once at the interface of crust and mantle) does not retain moisture and supports only sparse vegetation. Indeed, this rust-colored formation sheds rocky debris across its slopes, creating a moonscape in the midst of Newfoundland's greenery. A Discovery Center, on the road to the Tablelands (Route 431), introduces visitors to the natural history of this fascinating landscape.

Monday, August 18, 2008

Gros Morne National Park

Named a World Heritage Site by UNESCO in 1987, Gros Morne National Park stretches along the northwest coast of Newfoundland. Among its varied habitats are rocky beaches, sandy coves, tiaga flatlands, vast peat bogs, boreal forest and alpine tundra. Our hikes today took us through most of these ecosystems though we didn't have the time, energy or equipment for a trek to the higher terrain.

A morning walk along the shore turned up great black-backed gulls, common terns and a variety of shorebirds, including a lone whimbrel. We followed this amble with a 2 mile hike to the edge of West Brook Pond which sits at the mouth of a scenic, glacier-carved canyon in the granite massif of the Long Range; the route crosses a broad wetland, broken by islands of black spruce and balsam fir. Songbirds along this trail included North Woods species such as white-throated sparrows, Wilson's warblers and black and white warblers. A third hike, short but steep, took us to the summit of Berry Hill, an isolated pinnacle that offers a magnificent panorama of the Park's western slope; the highlight of that climb (other than the view) was the presence of a bald eagle, soaring above the flatlands between the mountains and the Gulf.

Since these hikes occurred during the hours of full sunlight, our mammal sightings were limited to the noisy and numerous red squirrels. Hoping to see a moose, which are abundant in the Park, we took a drive along Route 430 at dusk; within 30 minutes, we had seen nine of these large herbivores, including three adult females with their rapidly growing calves. Of the nine, eight appeared along the side of the road and four crossed in front of our car. So far this year, ten auto-moose collisions have occurred in Gros Morne National Park!

Sunday, August 17, 2008

Crossing Newfoundland

Leaving St. John's in a pea-soup fog, we picked up the Trans Canada Highway and headed north, toward Gander. Along the way, the fog waxed and waned and a steady rain developed, true to our preconceived image of Newfoundland. Scenic bays, coastal ranges and inland bogs adorned the landscape as the highway undulated northward, crossing numerous clear-water streams.

Nearing Gander, the terrain began to flatten and Route 1 angled westward toward Grand Falls -Windsor. Shallow lakes, meandering rivers and the ever-present bogs created a mosaic of wetlands across the rolling tiaga, ideal habitat for the numerous moose that inhabit this island. The western ranges began to appear east of Deer Lake, increasing in elevation toward the Gulf of St. Lawrence. Fortunately, the skies began to clear as we entered this mountainous terrain and our drive into Gros Morne National Park was accompanied by a beautiful sunset.

Over the next two days, we plan to explore the trails of this spectacular refuge, which is draped across the tallest peaks in Newfoundland. More on the Park in tomorrow's blog.

Saturday, August 16, 2008

Witless Bay

Located on the Atlantic Coast of southeast Newfoundland, Witless Bay is famous for its large colonies of sea birds, including 300,000 pair of Atlantic puffins, the largest concentration of this species on the planet. The various sea birds, which include puffins, murres, black guillemots and black-legged kittiwakes, nest on the cliff-edged islands that form a chain across the broad mouth of the bay. Protected within the Witless Bay Ecological Reserve, access to the islands is limited to research personnel but a number of local companies offer boat tours of this scenic marine refuge.

Today's tour, blessed by sunny, mild weather, met all of our expectations. Puffins were abundant, guarding their burrows or flying to and from the islands to provide food for their lone youngster; Atlantic puffins mate for life, raising a single offspring each year. Lower cliffs were nearly covered by nesting kittiwakes while large colonies of common and thick-billed murres clustered at favored sites. Though I spotted a flock of razorbills moving across the bay, their nesting season appeared to be over and none were spotted on the islands; likewise, the black guillemots had apparently moved out to sea for the winter months.

Herring and great black-backed gulls, gannets and common terns rounded out the seabirds on today's tour and we had the good fortune to see several humpback whales during our time on the bay. Tomorrow, we plan a drive across the heart of Newfoundland and will spend two days at Gros Morne National Park, on the western coast of this magnificent island.

Thursday, August 14, 2008


Guarding the mouth of the St. Lawrence River, Newfoundland, in combination with Labrador, is Canada's easternmost Province. Over the next week, my wife and I will be exploring this island for the first time and are looking forward to witnessing its stark beauty, abundant wildlife and varied landscape.

Newfoundland has an interesting geologic history. Its eastern third was once part of the Eurasian Plate while its western mountains are an extension of the Northern Appalachians; between these geologic regions is an uplift of ancient marine sediments, once the floor of the Iapetus Ocean. This ocean closed as Earth's continents merged into Pangea (during the Permian Period) and its crust was forced upward and over the junction of the North American and European land masses. When the Atlantic Ocean opened, it rifted to the east of this old suture line, wrenching westernmost Europe from its former Plate and attaching it to the North American Plate. Today, Newfoundland's stratified geology reflects the sequence of those tectonic events.

The rugged landscape of Newfoundland, molded by Pleistocene glaciers and the harsh, North Atlantic climate, is famous for its rocky coasts, icebergs, scenic fiords and tiaga ecosystems. Naturalists are also drawn to the island by its large colonies of sea birds and its varied population of whales. Newfoundland is home to the largest black bears on the Continent and to large herds of caribou and moose; these latter herbivores were introduced in the early 1900s and the island now harbors the greatest concentration of moose in North America.

Wednesday, August 13, 2008

Active and Passive Margins

As discussed in a previous blog, the geographic Continents due not often correspond to the borders of their respective tectonic plates. Since earthquakes and volcanoes are concentrated along the plate margins (where compression, friction and/or subduction occur), a given Continent is susceptible to these geologic events if it lies along or near these "active" margins.

North America has an active western margin and a passive eastern margin. Its plate, forming at the mid Atlantic Ridge, is inching westward. In the Pacific Northwest, this motion is causing the Juan de Fuca and Pacific plates to subduct beneath the advancing edge of North America; earthquakes and volcanoes are thus common along that margin. In the Southwest, the Pacific plate is scraping northwestward along the North American plate (at the San Andreas Fault), producing frequent earthquakes in that region.

By contrast, the East Coast of North America, lying atop the central portion of the Continental Plate, is not prone to geologic upheaval (though minor quakes can occur along old rifts and faults). Rather, this passive margin, characterized by a broad continental shelf, has experienced geographic alterations related to fluctuations in sea level. During periods of glaciation, when sea level was much lower, the coast was much further east than it is today. As the climate warmed and the sea level rose, the coast shifted west, leaving offshore islands and peninsulas of high ground; Long Island, Martha's Vineyard, Nantucket, Cape Cod, Nova Scotia and Newfoundland are examples of these remnant landscapes.

Tuesday, August 12, 2008

Infidelity and Gay Marriage

The recent news about John Edwards places him in a long line of politicians, religious leaders and celebrities who have succumbed to the natural sexual tendencies of the human male; there is no reason to believe that marital infidelity is any less common in the general population and divorce rates reflect that reality. The effort to encourage and enforce monogamy, the key ingredient of a family-based society, has always met with limited success.

It is ironic that some of these same politicians and religious leaders are such staunch opponents of gay marriage. Homosexuality, an inborn trait of an estimated ten percent of humans, has long been derided as a "sinful and irresponsible lifestyle" which promotes casual sex and promiscuity. One would think that these pious protectors of society would thus welcome the committed relationships that gay marriage is bound to encourage. Rather, entrenched in their "principles," these outwardly loyal men oppose legislation to sanction these unions. It is the epitome of hypocrisy (just ask their mistresses!).

Monday, August 11, 2008

Sand, Water and Time

The Entrada Sandstone of eastern Utah was deposited during the Jurassic Period, when dinosaurs roamed the planet and the Atlantic Ocean was beginning to open. Over the next 100 million years, this sand layer was buried by younger sediments of the Cretaceous and Tertiary Periods, slowly compacting into the rock formation that we see today.

During the Miocene and Pliocene Epochs (about 25 to 5 million years ago), the Intermountain West underwent a gradual uplift, adding five thousand feet to the elevation of the region and augmenting the erosive power of its many streams. This water erosion increased dramatically during the cool, wet climate of the Pleistocene as heavy precipitation and torrents of glacial meltwater carved the landscape. Throughout this extended period of uplift and erosion, the sediments that covered the Entrada Sandstone were carried away and the formation was dissected by numerous streams, creating the spectacular landscape of Arches National Park.

Today, the Park harbors the planet's largest collection of rock spans, one of which, Wall Arch, collapsed this past week. Gradually thinned by wind and water erosion (including rock falls from freeze-thaw cycles), the arches eventually give way, adding to the rock debris that covers the floor of this arid landscape. Over time, all of the scenic structures will disappear, the remnants of the Entrada Sandstone will be washed into the Colorado River system and older rocks will adorn the surface. Of course, new layers of volcanic debris, windblown sand or sea sediments may recoat the area during this process.

Sunday, August 10, 2008

Humans and Aging

Today is my 58th birthday, a notch closer to the end of middle age. But, having seen a few friends and many patients die young, I never focus on my age. Besides, the practice of medicine has taught me that life is fickle and that age does not always correlate with one's functional abilities. Those who adhere to a healthy lifestyle (and are fortunate enough to escape serious illness or injury) can expect to remain active and productive for most, if not all, of their life.

When man first evolved, 125,000 years ago, his life span was a third of what we anticipate today. The rigors of a nomadic life style, the dangers of hunting, exposure to the elements and, of course, a complete lack of medical care, insured a brief tour on this planet. The advent of human culture and the domestication of plants and animals had a positive impact on man's longevity but this was balanced by the rise of communicable disease and more efficient means of warfare. In recent centuries, the advance of science has led to improved sanitation, the development of vaccines, the treatment of infections and the many other benefits of modern medicine and dentistry; unfortunately, our efforts to control population growth and to eliminate warfare have been far less successful.

One might anticipate that human life expectancy, now near 80, will continue to rise as medical advances test the limits of our physiology. There's even the hope that man will learn to control (or reverse) the aging process, ending his long search for the fountain of youth. But I have my doubts; unless there is a dramatic change in human behavior, we are likely to succumb to environmental pollution and resource depletion long before we find the key to immortality.

Saturday, August 9, 2008

The Ranchland Flycatcher

One of the most distinctive birds in North America, the scissor-tailed flycatcher is a summer resident of the Great Plains, from Nebraska to Texas. Favoring open country with scattered trees, it is usually seen alone or in pairs, perched on a power line or wire fence. Its long, deeply forked tail, comprising more than half its total length, often attracts the attention of even the least observant traveller.

The spring courtship of scissor-tails involves a graceful, aerial ballet, after which a bulky nest of sticks is placed in an isolated tree. As with most flycatchers, insects, caught on the wing, are their only food and they must depart for balmy climes before the autumn chill. Most scissor-tails winter in Central America, though some head for South Florida and small numbers may turn up along the western Gulf Coast.

The range of this attractive bird, like that of many other species, has been expanding in recent years as they are forced to adapt to a variety of grassland habitats. Their aggressive nature, similar to the behavior of kingbirds, has likely played a key role in this expansion.

Friday, August 8, 2008


With all the rain and heat, it's been a good summer for tomatoes in central Missouri. In fact, a friend who has a farm southeast of Columbia brought me a sack of yellow and red globes just the other day; delicious and nutritious (a good source of Vitamin A, C and lycopene, a potent antioxidant), they were much appreciated.

One would think that tomatoes originated in Italy, considering the cuisine of that country. But current evidence suggests that ancestral tomatoes grew in the highlands of Peru and Bolivia and that they were first domesticated in Central America. Spanish explorers brought their seeds to the Mediterranean region and to Southeast Asia in the 16th Century; however, since their foliage resembles that of the deadly nightshades (to which they are related), they were initially thought to be poisonous and did not become part of the European diet for another hundred years or more.

British settlers brought tomatoes to North America in the late 18th Century and, today, the U.S. is second only to China in their production. Though commonly considered a vegetable, the tomato is a fruit from the botanist's point of view; its parent plant, a branching vine, is a perennial in warm climates but is grown as an annual in temperate regions. A close cousin of chili peppers and eggplant, the tomato is widely cultivated across the globe and is now represented by more than 7000 varieties.

Thursday, August 7, 2008

Fall Preview

A trough (a dip in the jet stream) has been pushing into the Midwest over the past few days and will continue to deepen through the coming weekend. Preceded by bands of thunderstorms, this wave of cooler, drier air is pushing our hot, muggy summer to the south and bringing a taste of fall to the Heartland. While the temperatures will be about 10-15 degrees (F) cooler than in recent weeks, it will be the lower humidity that makes all the difference.

On my walk to work this morning, it was clear that the mild conditions had reinvigorated the neighborhood wildlife. Squirrels and cottontails were more active and birdsong had a renewed intensity. Then again, it may have been an illusion, the result of my own increased awareness in the pleasant, autumn-like air.

Of course, this respite from summer will be all-too-brief. The trough will shift east and flatten northward within a few days and hot, humid air will drift back from the south. Until then, we'll emerge from our air-conditioned bunkers and enjoy the fall preview!

Wednesday, August 6, 2008

Hominids, Volcanoes and the Pleistocene

The Pleistocene Epoch, commonly known as the Ice Age, began 2 million years ago (MYA). Four major glacial advances occurred during this Epoch, separated by warm interglacial periods; most climatologists believe that the Holocene, which began 10,000 years ago and continues today, is just another interglacial episode and that glaciation will redevelop within 10-15,000 years. More than an era of glaciers and Ice Age fauna, the Pleistocene witnessed significant volcanic activity and the final stages of human evolution; the role that volcanism played in the climate swings of the Pleistocene (and thus in the rise of humans) remains a point of controversy.

At the beginning of the Pleistocene, the first and major eruption of the Yellowstone Caldera occurred, Mt. Kilimanjaro (consisting of three volcanoes) rose along the African Rift and the San Francisco Peaks formed in the volcanic field of northern Arizona. At the same time, Homo erectus appeared in Africa; equipped with precise hand function and a pelvis that favored upright posture, he was the first hominid to use fire and spread to southeast Asia by 1.8 MYA. Today's major Cascade volcanoes began to form 1.6 MYA, the second eruption of Yellowstone occurred 1.2 MYA and the Valles Caldera of New Mexico's Jemez Mountains erupted 1.1 MYA.

Mauna Loa, the largest volcano on Earth today, first erupted 700 thousand years ago (TYA), followed by the third eruption of Yellowstone (600 TYA) and Mt. Ranier's first eruption (500 TYA). Homo heidelburgensis appeared in Africa 200 TYA; those that spread northward into Eurasia gave rise to the Neanderthals while those remaining in Africa, cut off and molded by drought, evolved into Homo sapiens (125 TYA). Finally, humans were nearly wiped out by the massive eruption of Toba (on Sumatra, 74 TYA); those that survived (perhaps as few as 10,000) have since colonized the globe and, in the process, triggered the demise of Neanderthals by 30 TYA.

Tuesday, August 5, 2008

A Heat Sandwich

The dome of high pressure that has brought intense heat to the south-central States over the past few weeks is beginning to flatten west to east as the jet stream dips across the Northern Plains and Great Lakes region. The clash between this cold front and the northern rim of the heat dome brought severe storms to Chicagoland last evening and, as the jet pushes southward, the thunderstorms will follow. By tonight, the storm line is forecast to stretch from the Central Plains into the Ohio Valley.

Meanwhile, on the southern side of the heat dome, Tropical Storm Edouard, which formed in the northeastern Gulf of Mexico, has moved westward, following the rim of high pressure. This morning, the storm is coming ashore near the Texas-Louisiana border and, hopefully, will bring much needed rain to the southern Plains. Had the heat dome not been in place, the storm would have likely moved northeastward earlier in the week as a less intense cluster of storms.

For now, the heat dome is sandwiched between the approaching cold front and the tropical storm. Over the next few days, its remnants will likely persist along the Texas-Oklahoma border while the cold front, energized by the jet stream, brings a taste of early fall to the Midwest and Eastern States.

Monday, August 4, 2008

Canyons and Time

Fifteen years ago, my family visited Mesa Verde National Park, in southwest Colorado. Exploring the Sun Temple, we were suddenly startled by an explosion that echoed through the adjacent canyon and looked up to see a massive sheet of rock crashing down the canyon wall, bulldozing trees and everything in its path.

Initially carved by streams and glaciers, the valleys, canyons and gorges of our planet continue to erode through time. The primary stream and its tributaries relentlessly deepen the central chasm and its side canyons while the width of the gorge expands through other processes. Snowmelt and rain enter fissures in the rock walls and these cracks expand when the water freezes; over time, slabs of rock break from the wall of the gorge, tumbling into the valley below. These slump blocks are eventually broken down into smaller rocks by the same freeze-thaw cycle.

In other cases, rivulets of rain and snowmelt gradually erode soft layers of the canyon wall (shales, mudstones), producing recessed caves; when the loss of support reaches a critical point, the overlying rock layers collapse, sending massive boulders down the slope. Finally, in areas of poorly compacted sediment, prolonged or heavy rains saturate the outer layers of the gorge wall, which eventually pour into the valley as an avalanche of rock and mud. Over millions of years, these processes blend the canyon with the surrounding uplands, producing a rolling landscape with less dramatic relief; of course, this transition is much slower in arid regions.

Sunday, August 3, 2008

Flash Flood Aftermath

Forum Nature Area, in Columbia, Missouri, stretches across the floodplain of Hinkson Creek. Covered by a restored prairie and seasonal wetlands, the preserve catches drainage from surrounding uplands and its ecosystem is in constant flux as water levels rise and fall.

Having not visited the refuge for the past two weeks, my wife and I were surprised by the carnage along the southwest border of the seasonal lake. Heavy thunderstorms, abundant over the last month, had clearly sent a raging torrent through the preserve, uprooting willows, scouring away the gravel trail and covering numerous shrubs and saplings with silt and plant debris. High winds had also taken down several large trees and the refuge vistas had suddenly changed.

Unfazed, bullfrogs and green frogs croaked along the shoreline, green-backed herons stalked prey from the downed trees and a family of Canada geese plied the still waters. Away from the flood's path, prairie wildflowers adorned the grassland and resident songbirds moved through the woods, oblivious of the altered habitat. Of course, such seasonal floods created the valley in which the refuge lies; now and then, we are fortunate to witness the natural forces that have molded (and continue to mold) our planet.

Saturday, August 2, 2008

The Sounds of August

By August, the heat and humidity are taking a toll on most birds and mammals, including humans. The morning brings half-hearted tunes from robins and cardinals but bird song is otherwise limited to the occasional rant of a jay or crow, the twitter of energetic swifts and the evening peents of the nighthawks. Even the drone of lawnmowers has become less common as the grass has slowed its growth and suburbanites have lost their enthusiasm for yard work.

In contrast, insects, oblivious to the heat, have assumed the choral duties. Annual cicadas, frantic to find a mate during their brief lives, call from the broadleaf trees, their irritating but nostalgic tune rising and falling in unison. A variety of beetles and grasshoppers join this late summer chorus and evening brings a substantial contribution from the fiddlers: crickets and katydids. The latter insects sing until morning, their scratchy tunes a classic feature of Midwestern, August nights.

Before long, the cool nights of September will suppress the insect chorus and the first hard freeze will officially end their run. By then, the birds and mammals are reinvigorated and the calls of owls, coyotes and migrant waterfowl propel us into autumn.

Friday, August 1, 2008

Summer Migration

Entrenched in the hot, muggy Midwestern summer, it is difficult to imagine that the fall migration is already underway. But, in fact, many shorebirds, having raised their young on the Arctic tundra, have been filtering through the Heartland for the past few weeks, headed for southern coasts.

The number and variety of these sandpipers and plovers will peak in late August to mid September but the first flocks move south by early-mid July. As most birders know, these long distance travellers are best found in flooded fields or on the mudflats that line our lakes and reservoirs; there they stop to rest and feed between legs of their long, biannual journey.

Due to their relatively small size and skittish nature, shorebirds are best viewed from a distance with binoculars or a spotting scope; at wetland preserves with graveled roadways, using your car as a blind permits a closer approach. One marvels at the stamina of these world travellers and, when viewing them in the shimmering heat, is reassured that cool, drier days are on the horizon.