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Showing posts from September, 2008

Two-Plate Countries

The great majority of the countries on this planet lie completely upon their respective Continent's plate. However, there are some that straddle two tectonic plates and are thus especially susceptible to earthquakes.

Iceland is the most obvious example; rising above the mid Atlantic Ridge, the western half of this island nation lies on the North American Plate while the eastern portion is part of the Eurasian Plate. While almost all of the continental U.S. and Mexico occupy the North American Plate, Southern California and the Baja are inching slowly to the northwest atop the Pacific Plate. Easternmost Russia and northern Japan lie on the North American Plate while the remainder of these countries sit on the Eurasian Plate. New Zealand also straddles two plates; its North Island and the northwest portion of its South Island lie on the Australian Plate but the rest of the South Island occupies the Pacific Plate.

But the most complex assembly of countries and tectonic plates is in…

Winter's First Jab

Thunderstorms are rumbling across Missouri this morning, the leading edge of a cold front that will bring us the first significant chill of the season; the rest of the week is expected to be dry, with highs in the 60s (F) and lows in the 40s. Spring and fall are the battle-grounds of winter and summer and this appears to be winter's first jab.

The weather gyrations of spring and fall coincide with an undulating jet stream, which creates an alternating pattern of cool and warm weather across the Heartland. Troughs (dips in the jet) allow Canadian air to spill southward while ridges (northward curves in the jet) open the Midwest to a warm, humid flow from the Gulf of Mexico. As autumn progresses, the jet will gradually move southward and flatten out; broad troughs will dominate the region and the chill of winter will become entrenched. By then, winter will have won the battle and summer will not renew its challenge until March.

Tropical Canada

After forming in the Caribbean as a tropical depression, the storm that would become Hurricane Kyle brought heavy rains to Puerto Rico and the Dominican Republic. Then, drawn northward by an upper low off the Carolina coast, it became a tropical storm, passing just west of Bermuda. An approaching cold front continued to accelerate the storm and, moving north across the warm Gulf Stream, Kyle became a hurricane.

While most hurricanes fizzle out as they enter cooler waters of the North Atlantic, Kyle has been moving at a fast clip and its circulation has managed to hold together; this afternoon, the hurricane is about to make landfall across southern Nova Scotia and the south coast of New Brunswick. Heavy rains will lash Maine, west of its track, but the damaging winds and storm surge will be restricted to Canada.

Though nor'easters, produced by potent cold fronts, bring destructive winds and waves to this region on a regular (seasonal) basis, tropical hurricanes rarely reach this …

Hybrid Life Forms

Last evening, my wife asked me to look at something in the flower bed; it appeared to her that an animal had vomited on the bark mulch. With that description, I knew she had discovered a slime mold.

Despite their ugly appearance, slime molds are fascinating organisms that demonstrate features typical of both plants and animals. Once classified as Myxomycota, within the Kingdom of Fungi, slime molds are now placed in their own Kingdom (Protista) by many mycologists; beyond the confusion regarding their classification, slime molds are a heterogeneous group, generally divided into cellular and plasmodial forms. Beginning life as a spore, this mystery organism initially becomes either an ameoboid cell or a flagellated swarm cell; the former group fuse into plasmodial species while the latter stick together to form cellular mats. The plasmodial forms may be a few centimeters to several feet in diameter; in either case, the individual cell walls break down and the parent slime mold looks lik…

Natural Health

As a physician, I know that many medical problems are not preventable; genetic disorders, many infections, accidents and a variety of cancers fall into this category. And I also realize that modern medications and procedures have significantly improved the quality and longevity of our lives; vaccines, antibiotics, insulin and sterile surgical techniques are just a few examples.

But many of the maladies that afflict humans are partly or totally preventable. Furthermore, the treatment of these "lifestyle diseases" levies a heavy toll on our society. Inactivity, poor dietary habits, tobacco use, excessive alcohol consumption, drug abuse and other risky behavior are at the root of many of our most common and most costly medical problems. Too often, humans indulge in these behaviors, believing that medications and/or surgical procedures will bail them out down the line. As a result, many of them end up with a history of multiple operations and a long list of daily medications (som…

Cuyahoga Valley National Park

As the last Pleistocene glacier, the Wisconsin, retreated into Canada, some 14,000 years ago, the Cuyahoga River and its tributaries began to erode a scenic valley in northeast Ohio. Protected as a National Recreation Area in 1974, this 33,000 acre wonderland, rich in human and geologic history, is now a National Park. Access to the preserve is via I-271 (Exit 12) or eastward from I-77 via S.R. 82 or Pleasant Valley Road (the Independence Exit).

Erosion along the walls of the Valley has uncovered 60 million years of geologic history; outcrops of Sharon Conglomerate, Pennsylvanian in age, dot the ridge tops while cliffs of Devonian shale rise along the river. Middle layers of the gorge are composed of Mississippian sediments, including Bedford Shale and Berea Sandstone. Groves of Canadian hemlock, relics of a periglacial ecosystem, cover shaded slopes of the valley, adding diversity to the rich, deciduous forest.

Numerous trails wind through the Park, taking visitors to secluded wate…

The Fall Migration

Though we have just officially entered the autumn season, the fall migration of North American birds began back in July as the first shorebirds drifted south through the Heartland. This movement of plovers and sandpipers, from Arctic breeding grounds to southern beaches, will continue into early November.

Meanwhile, other migrations have begun, led by common nighthawks in late August. These insect hunters are still passing through Missouri, joined by summer songbirds throughout September; by mid October, most of these fair-weather species will be gone and winter residents will be arriving from the north. The duck migration, which begins with the exodus of cinnamon and blue-winged teal in September, will continue into December, generally peaking in number and variety by early November; early ducks are accompanied by American white pelicans while cormorants, loons and grebes move with the later groups.

By early November, the migrant geese begin to arrive in America's Heartland, p…

Hawks in Flocks

Most hawks are solitary creatures. They are seen in pairs during the breeding season and may gather in small groups at favored hunting grounds but otherwise spend much of their lives alone. And, unlike most birds, the great majority of these predators do not migrate in flocks; three exceptions are native to North America.

The broad-winged hawk, a small buteo with prominent tail bands, is unusual in two respects. In contrast to most buteos, which live and hunt in open country, this crow-sized hawk inhabits deciduous forests where it hunts from a secluded perch for mice, snakes, lizards and small insects. By mid September, broad-wings, which range across the eastern half of the Continent, gather in large flocks and begin their migration to South America. Taking advantage of updrafts along the Appalachian ridges, they may be seen in flocks of a hundred or more; Hawk Mountain, in Pennsylvania, is renowned for these sitings.

Swainson's hawks, large buteos of the American West, also m…

Ocean Floor Topography

Looking out at the vast, blue ocean, one might assume that its floor is as flat and featureless as its surface. But, in fact, the ocean floor has the same variety of topography that we see on land: mountains, hills, plains, basins and canyons. The ocean floor forms at the mid ocean ridges and moves off toward the oceanic trenches, where it is consumed back into the mantle; along the way, deposition, erosion, fault motion and volcanism mold its surface.

More than 30% of the ocean floor is covered by volcanic ridges; most of these are aligned along the spreading zones, where new ocean crust is forming and where the bordering tectonic plates are being pushed apart. In other areas, these ridges have developed over a volcanic hot spot and extend off in the direction of the plate motion; the Hawaiian Ridge is an excellent example of a regional volcanic ridge. The summit of most volcanic ridges are well below the surface of the ocean but some are tall enough to exceed sea level, forming clust…

Staying Together

Since this is my 33rd Wedding Anniversary, it seems like a good time to revisit the subject of monogamy. As I have expressed in past blogs, the study of natural history suggests that monogamy is not a natural human condition; rather, it has been encouraged (if not imposed) by religious and cultural laws. However, most of us would agree that, in our complex, modern society, a stable, committed, monogamous relationship offers the ideal environment for the healthy development of children. Nevertheless, the divorce rate continues to hover near 50% in developed, Western cultures.

Some marriages are sustained solely through the power of guilt, a response to religious and social pressure. Others work due to the interdependent psychological needs of the partners. But it seems to me that most successful marriages reflect the willingness of the partners to give each other space.

Humans are social creatures. However, most of us require periods of solitude and cherish the freedom to pursue in…

Breeding Champs

There seem to be more meadow voles on our Littleton farm this year. Perhaps this is due to a better food crop following the copious rain and snow this spring; more likely, it reflects the eviction of our fox family, primary predators of these prolific rodents. Then, again, we have plenty of hawks, kestrels and owls around to keep their numbers in check.

Meadow voles spend most of their brief life in burrows and runways beneath dense grass (or beneath snow in the winter); several of their entry portals are evident along our driveway, which borders one of the pastures. Females are able to breed by one month of age and, in their 12-18 month lifespan, produce a litter of 4-12 youngsters every 3-4 weeks; to some degree, birth rates rise and fall relative to the local food supply. Obviously, meadow voles are one of the most prolific mammals on the planet.

When not breeding, these voles are eating, consuming over 50% of their body weight each day. Active day and night, they feed primarily…

The Scratchers

Many birds attract our attention with their colorful plumage; certain buntings, grosbeaks, tanagers, orioles and waders come to mind. Others have distinctive calls; even novice birders can identify magpies, crows, blue jays, flickers and belted kingfishers without actually seeing them.

Then there are the scratchers. While most ground-feeding birds sift through leaf litter for seeds or insects, some species are especially vigorous in this regard; robins, thrashers, hermit thrushes and fox sparrows are excellent examples. But the king scratchers are the towhees and their energetic feeding style often calls our attention to their presence.

Of the four species in North America, the rufous-sided towhee is the most common and widespread; this species, which has eastern and western races, is a permanent resident in much of the U.S., though it departs more northern regions in winter. Here in Colorado, it is joined by the green-tailed towhee, which inhabits foothill shrublands and canyons du…

Cottonwood Cathedrals

On my frequent walks along the South Platte River, I often stop to enjoy the shady, peaceful environment of the cottonwood groves. Common along the rivers and creeks of eastern Colorado, between elevations of 3500 and 6000 feet, the plains cottonwood matures into a massive tree with a thick trunk and a wide, branching crown. Older groves are cathedral-like in their natural splendor and provide home to a wide variety of creatures.

Magpies and hawks construct bulky nests in their upper branches, often used by great horned owls in later years. Fox squirrels, raccoons, opossums, screech owls, wood ducks and bats use cavities in these majestic trees and their spreading crown attracts riparian songbirds; among the latter are western wood pewees, yellow warblers, chickadees, white-breasted nuthatches, downy woodpeckers and northern orioles. Northern flickers often dominate these groves and dead trees are favored nest or roosting sites for bald eagles, ospreys, double-crested cormorants, great…

A Hornet Nest

Since my last visit to our Colorado farm, a gray, basketball-sized, turban-shaped globe has appeared in one of our apple trees; not to be mistaken for a pinata, this is, of course, a hornet nest. No doubt present during my visit in July, the nest has "grown" to a more conspicuous size over the past two months.

Pregnant female hornets emerge from their winter retreat in spring and lay eggs in a cluster of paper cells that they attach to a tree limb; unlike other wasps, they enclose these cells in a protective envelope (the "paper" is formed by salivary digestion of wood scraps). Once the eggs hatch, the attentive queen feeds them until the larvae pupate; emerging as sterile female workers, this initial brood returns the favor by expanding the hive and tending to the queen, who will continue to lay fertilized eggs throughout the spring and summer. Space for the new egg chambers is made by scraping away the inner layer of the envelope and adding a new layer to the o…

Back on the Farm

It's good to be back at our Littleton, Colorado, farm, if only for a week. September is always a good time to visit and, since I was last here in July, there has been a significant change. Recent rains have greened-up the "lawn" and the trees and shrubs look especially vibrant for late summer. It's been a good year for pears, apricots and crab apples but the other apple trees have a rather sparse crop. The mulberry trees have been picked clean by the robins, orioles and house finches but there's plenty of juniper berries to last the winter.

The rose of sharon and trumpet vines are still in bloom, attracting our resident hummingbirds and a few migrants from the mountains. Other visitors have included western wood pewees, Lincoln's sparrows, rufous-sided towhees, yellow warblers, western tanagers and a surprising number of blue-gray gnatcatchers. The collared doves and lesser goldfinches, first seen in July, are still hanging around, joining the usual mix of chi…

The Yellowing

After days of heavy rain, there was nothing but brilliant sunshine on my trip to Colorado today; only the distant smoke of power plants and shimmering clouds of starlings marred the deep, blue sky. A dome of high pressure had settled over the Plains, clearing the air and stifling any wind; the turbines at the Smoky Hills Wind Farm, west of Salina, were nearly stationary.

Despite the spectacular weather, wildlife was scarce on my drive along the interstate. Turkey vultures tilted above the shallows of the Missouri River floodplain, searching for victims of the deluge. Red-tailed and Swainson's hawks hunted along the highway, several herds of pronghorn grazed the High Plains near Limon and the occasional box turtle tempted fate on our concrete ribbon of death.

Most noticeable were the changing colors of the landscape. Summer greens had faded to olive, the Flint Hills tallgrass was tipped with gold and a variety of sunflowers, coneflowers and goldenrod adorned the grasslands of Mis…

Ike's Reign

Born two weeks ago, off the coast of Africa, Hurricane Ike ravaged several islands of the Caribbean before spinning into the Gulf of Mexico and growing into a massive, category 2 storm. Leaving a broad swath of water and wind damage across coastal Texas and Louisiana, it moved inland and brought heavy rains to northeast Texas, eastern Oklahoma and Arkansas.

Over the past twenty four hours, an approaching cold front nudged Ike to the northeast and, as of this morning, its remnant depression was centered over southeast Missouri. Here in Columbia, we received torrents of rain before the winds shifted from the north, indicating that the "backside" of Ike's circulation had arrived. Making a beeline for Chicago, Ike will leave more flooding before its reign ends over the Great Lakes region.

Though the route of these storms may seem aimless, their motion is a reflection of upper air flow which, in turn, is governed by the jet stream pattern. Once Ike entered the Gulf of Mexic…

Storm Surge

As hurricanes come ashore, they cause destruction via heavy rain, high winds and storm surge; the latter is often least appreciated by coastal residents and visitors. The amount of rainfall is most closely related to the forward speed of the hurricane; the slower it moves, the more rain it drops on any given area. The wind damage correlates with the strength of the hurricane; the lower the central pressure, the higher the sustained wind speed and, thus, the greater the impact on structures.

The storm surge refers to the buildup of ocean water ahead of the storm. As the hurricane comes ashore, it acts like a giant plow, forcing a broad river of water toward the coast; this phenomenon is greatest to the right of the storm's center, reflecting the counter-clockwise motion of the surface winds. The threat from storm surge is related to the size of the hurricane and to the region's topography; flat coastal plains that lie along shallow bays are especially vulnerable.
If the coastal w…

Earthquake Central

Looking at a map of the North Pacific, one finds that the Aleutian Chain of Alaska is continuous with other islands off the east coast of Asia; the latter include the islands of Japan. This curving line of islands marks the southern edge of the North American Plate, which extends northward to include eastern Siberia; south of Tokyo, the Japanese islands lie on the eastern edge of the Eurasian Plate. Indeed, Japan lies at the intersection of four major tectonic plates: the North American, Eurasian, Philippine and Pacific Plates.

The North American and Eurasian Plates are colliding in the center of Honshu, Japan's largest island; though the exact position of this collision zone remains controversial, most geologists place it just southwest of Tokyo. The Philippine Plate is subducting beneath the Eurasian Plate along the southern margin of Japan while the Pacific Plate is subducting beneath the North American Plate along the eastern edge of this island nation. Finally, to the sout…

A Balmy Flow

The same high pressure dome that is deflecting Hurricane Ike toward Texas is pulling warm, moist air into the Midwest. Unlike the cool, dry air of this past week, this balmy air mass resists heating and cooling; our highs and lows of the next two days will be within 6 or 7 degrees F of each other while temperatures spanned a range of 20-25 degrees F when the air was dry and the skies were clear.

Our overnight low was 67, producing a frenzy of insect calls more typical of mid August. Just ten days short of the equinox, these crickets and katydids feel the instinctual pressure to breed before the autumn chill ends their reign. Many humans, disdainful of the cold, also welcome this balmy flow, a short-lived respite from the march toward winter.

Showers developed this morning and, as the next cold front approaches, the rain will intensify tonight. By the weekend, autumn will reclaim the Heartland.

September in Colorado

Though October gets the nod in the Midwest, September is my favorite month in Colorado. Mild days and cool nights typify the weather and snow dusts the high peaks, heralding a change in the seasons. Out on the Eastern Plains, large flocks of gulls, waders, shorebirds, cormorants, pelicans and early waterfowl gather at the larger reservoirs, preparing to migrate to southern climes.

Songbirds are moving south along the foothills while, in the higher mountains, some species are preparing their descent to lower elevations for the winter. In like manner, Colorado's elk begin their journey to mountain valleys and foothill meadows and, by the end of the month, the bugles of the adult bulls echo through the high country. The quaking aspen start to turn by the middle of the month, producing shimmering blankets of gold as September wanes.

Best of all, the summer crowds have dispersed and hikers can enjoy this mountain splendor in relative solitude. Glorious weather, spectacular scenery, …

Harvest Loon

September is usually a good time to visit Eagle Bluffs Conservation Area, southwest of Columbia. The songbird migration has begun, shorebirds are peaking, blue-winged teal are beginning to arrive and large flocks of white pelicans and great egrets congregate there before heading south. Looking forward to this annual spectacle, I headed down to the refuge last evening.

Entering the preserve, I found a large number of turkey vultures roosting on the transmission towers and spotted a lone bald eagle flying above the Missouri. A pair of white-tailed deer bolted for the woods as I approached and cottontails scampered from the roadway at every bend. Other than those expected encounters, the refuge was remarkably quiet. Green-backed herons were well represented and the occasional great blue heron stalked the shallows; but only a couple of great egrets flapped across the wetlands and, other than a lone coot, the only waterfowl were a group of decoys placed by a hunter. Only the red-winged blac…

Hurricane Season

The Atlantic Hurricane Season begins on June 1 and ends by mid November; the second week in September generally represents the peak of hurricane development. Early in the season, tropical depressions (the precursors of tropical storms and hurricanes) usually develop from disturbances over the warm waters of the Caribbean and Gulf of Mexico. If not aborted by strong, upper-level winds or by interaction with areas of inversion (sinking, dry air), these isolated depressions feed on the heat and humidity of the tropical atmosphere, develop rotating clusters of thunderstorms and may give rise to a tropical storm; the latter becomes a hurricane if its peak, sustained winds reach 74 mph.

By mid summer, the easterly African jet stream begins to carry waves of low pressure into the tropical Atlantic. Drifting westward, these waves may progress to tropical depressions and thence to tropical storms and hurricanes. In many cases, cold fronts, moving east off the coast of North America, deflect…

Man, Intelligence and Knowledge

When man first appeared, 125,000 years ago, he had the same intellectual capacity that we have today. Though, like any human trait, intelligence varies between individuals, all healthy members of our species are equipped with the brain power to learn, to understand and to communicate; of course, some take more advantage of this potential than do others.

Our human ancestors used their intelligence to understand the nature of their environment, to gather food, to avoid danger and to protect themselves from the elements. Over time, experience and experimentation have greatly increased our knowledge but the innate intelligence of our species has not changed. Though we have the same intellectual capacity as those first humans who spread from Africa, the combined effects of curiosity, exploration, communication and hard work (mental and physical) have led to an exponential growth of our knowledge. Today's average high school student has a better understanding of many scientific issu…

Desert Formation

Deserts are generally defined as geographic regions that receive an annual average precipitation of 10 inches or less. Many factors combine to produce such a low level of precipitation but three conditions tend to predominate.

Most of the deserts on this planet are aligned along the Tropics of Cancer and Capricorn where persistent high pressure zones cause the air to sink; sinking air compresses, dries out and heats up, creating an atmosphere of low humidity and sparse cloud cover. The dry air, abundant sunshine and radiant nocturnal cooling lead to wide swings in temperature throughout the 24-hour cycle; hot, sunny days and chilly, clear nights characterize these desert regions for most of the year. These conditions are hostile to most species of vegetation, minimizing plant transpiration and further reducing the natural processes that humidify the atmosphere.

Similar climatological factors often lead to desert formation on the lee side of mountain ranges. Prevailing winds carry mo…

Gustav Visits Missouri

After ravaging much of Louisiana, Hurricane Gustav, now a Tropical Depression is centered over southwest Arkansas. Its counter-clockwise circulation is sweeping copious moisture into the Heartland, just in time to meet a potent cold front that is dropping through the Midwest. Combine these meteorologic events and you get continuous, flooding rains.

Here in central Missouri, light rain developed by dawn and waves of heavier precipitation have occurred throughout the day. A mild north wind (we are now behind the front) has kept the temperature in the lower sixties, quite a contrast from the summer heat of this past week. As the remnants of Gustav move northeastward along the front, our rain is expected to increase, totalling a couple of inches overnight and just as much tomorrow.

By the weekend, the cold front should be far enough east to keep us out of the rain; sunny skies and mild, dry air are forecast. Hurricane Hanna should be striking the Southeast Coast about then!

Sheltowee Trace Trail

As summer gives way to the glorious season of fall, hikers across the country search for new adventures. One of the better trails in the eastern U.S. is the Sheltowee Trace Trail, which winds across the Appalachian Plateau from Pickett State Park, in Tennessee, to Rowan County, Kentucky, north of Morehead. Running the entire length of Daniel Boone National Forest, the 257-mile route (Forest Trail 100) was named in honor of Kentucky's famous explorer; Sheltowee, which means Big Turtle, was the name given to Daniel Boone by local Native Americans.

On its course through Kentucky, the Sheltowee Trace crosses the Big South Fork National Recreation Area, winds past Cumberland Falls and skirts the north shore of Laurel River Lake. North of McKee, the trail curves along a scenic, rock-walled gorge and then drops to the Turkey Foot Recreation Area, on the War Branch of Station Camp Creek. Heading north, it eventually enters Natural Bridge State Resort Park, one of the most spectacular sites…

Celebrity Coast

Everyone who's anyone in the American media has gathered along the Louisiana coast to stand in the wind and rain as Hurricane Gustav comes ashore. Of course, the political fiasco that followed Katrina is part of their motivation but one would think that local news and weather personnel could provide the storm coverage. Perhaps these gods of American culture are convinced that we, the adoring American public, can only believe what they, the American media celebrities, have to report.

With all due respect to the suffering of Louisiana residents, it is time that we focus attention on the futility of living on floodplains and in areas protected by levees. Decades without a major storm or flood allow us to become complacent; we make assumptions based on what we have observed during our brief, human lives, an instant in natural history. Then, two major hurricanes strike within three years and the toll on society, measured in both human lives and financial costs, is staggering.

Hopeful…