Closely related to the six-lined racerunner of the Mid-Atlantic and Southeastern U.S., the prairie racerunner is found from northwestern Indiana and southern Wisconsin, westward to southern Wyoming and southward to Arkansas, West Texas and New Mexico. Favoring dry, sandy soil and hot weather, these lizards inhabit prairie grasslands, abandoned farms, glades and rocky hillsides; attracted to disturbed areas, they are known to spread along power line swaths and railroad lines. Here in Colorado, prairie racerunners are abundant from the High Plains to the shrub zone of the lower Front Range foothills.
Emerging from hibernation in late April or May, prairie racerunners are best observed during the morning and early afternoon hours of June and July, dashing across trails or clearings and disappearing into clumps of vegetation to snare prey or to avoid predators. Their long tail, twice the length of their body, is thought to serve as a counter-balance as they zig-zag at speeds up to 18 miles per hour. Mating occurs by late spring and five eggs are generally produced; as with most lizards, the hatchlings are miniature replicas of the adults and must fend for themselves. While a second brood may be produced within a few weeks, adult prairie racerunners begin to hibernate by late August or early September; the young, needing more time to generate fat stores, wait until late September or October to settle in their winter burrows (depending on their home latitude).
Feasting on a wide variety of insects and other invertebrates during their brief season of activity, prairie racerunners may fall victim to grassland hawks, prairie falcons, burrowing owls, fox, coyotes, roadrunners, magpies and a variety of snakes. Using shallow burrows during the warmer months, they dig a deeper channel with a terminal chamber for their prolonged hibernation; during that time, in sharp contrast to their frenzied life above ground, their metabolic rate falls dramatically and they rely on fat deposits to fuel their survival. If they make it through their first winter, adult prairie racerunners are thought to have a natural life span of 4-5 years.
Tampilkan postingan dengan label Great Plains. Tampilkan semua postingan
Tampilkan postingan dengan label Great Plains. Tampilkan semua postingan
Rabu, 11 Juli 2012
Sabtu, 09 Juni 2012
Dry Rivers on the High Plains
Most of the rivers that cross the High Plains of the American West would hardly be recognized as creeks farther to the east. While the primary rivers that rise in the mountains, including the Missouri, Yellowstone, Platte and Arkansas Rivers deserve their title, many of the smaller rivers, heading on the High Plains Province itself, are dry for much of the year, transmitting water only after episodes of torrential rain or rapid snowmelt. Among these sandy channels are the upper tributaries of the Niobrara, Republican and Smokey Hill watersheds.
Cut off from Pacific moisture by the Continental Divide and located far from the Gulf of Mexico, the High Plains only receive copious precipitation when powerful storms draw in moisture laden air from the east, events that most often occur from February through June; indeed, this geophysical province receives less than 20 inches of precipitation each year. Yet, if we study the High Plains topography, we find that these meager conduits have managed to carve ridges, hills and valleys from the otherwise level plain, suggesting that they were more substantial streams in the past. In fact, during the Pleistocene Epoch (2 million to 10 thousand years ago) the regional climate was much cooler and wetter, giving rise to rivers that, in today's climate, have withered to channels of sand, prairie grass and scattered stands of cottonwood trees.
As with other ecosystems across our globe, it is impossible to understand the current geography without an appreciation for natural history and the region's underlying geology. In the case of the American High Plains, Pleistocene rivers sculpted the Tertiary deposits and underlying Cretaceous Sea sediments into the landscape that we find today; feeble and intermittent streams now occupy the valleys that those rivers left behind.
Cut off from Pacific moisture by the Continental Divide and located far from the Gulf of Mexico, the High Plains only receive copious precipitation when powerful storms draw in moisture laden air from the east, events that most often occur from February through June; indeed, this geophysical province receives less than 20 inches of precipitation each year. Yet, if we study the High Plains topography, we find that these meager conduits have managed to carve ridges, hills and valleys from the otherwise level plain, suggesting that they were more substantial streams in the past. In fact, during the Pleistocene Epoch (2 million to 10 thousand years ago) the regional climate was much cooler and wetter, giving rise to rivers that, in today's climate, have withered to channels of sand, prairie grass and scattered stands of cottonwood trees.
As with other ecosystems across our globe, it is impossible to understand the current geography without an appreciation for natural history and the region's underlying geology. In the case of the American High Plains, Pleistocene rivers sculpted the Tertiary deposits and underlying Cretaceous Sea sediments into the landscape that we find today; feeble and intermittent streams now occupy the valleys that those rivers left behind.
Senin, 04 Juni 2012
High Plains Thunderstorms
Our trip from Missouri to Colorado today was almost entirely under sunny skies, with afternoon temperatures near 90 degrees F. The one, significant exception was an imposing wall of dark clouds, lightening and intense rain along the Kansas-Colorado border. Though our journey through the storms was brief and, thankfully, unaccompanied by large hail, the thunderstorms were training over Kit Carson County, including the city of Burlington, triggering a flash flood warning from the National Weather Service.
Encounters with severe weather can be unsettling in any location but they are especially terrifying on the Plains or on open water. In these areas, one gets both a broad view of the storm's size and ferocity and plenty of time to observe the approaching monster, wondering what it might do to your vehicle or boat. In addition, if caught in an open landscape, one experiences a sense of hopelessness, finding no means to escape the looming threat.
While some make their living chasing and photographing storms on the Great Plains, the rest of us are well advised to check weather forecasts prior to our journey and be willing to stop at a safe location if unexpected storms develop. Today's storms seemed to blow up before our eyes and we had no recourse but to slow down and hope for the best; fortunately, the major storms were well away from the highway as we passed through and we had only to contend with torrential rain and gusty wind. Once we were through this swath of fury, the clouds dispersed and we crossed dry, sun-drenched terrain all the way to Denver.
Encounters with severe weather can be unsettling in any location but they are especially terrifying on the Plains or on open water. In these areas, one gets both a broad view of the storm's size and ferocity and plenty of time to observe the approaching monster, wondering what it might do to your vehicle or boat. In addition, if caught in an open landscape, one experiences a sense of hopelessness, finding no means to escape the looming threat.
While some make their living chasing and photographing storms on the Great Plains, the rest of us are well advised to check weather forecasts prior to our journey and be willing to stop at a safe location if unexpected storms develop. Today's storms seemed to blow up before our eyes and we had no recourse but to slow down and hope for the best; fortunately, the major storms were well away from the highway as we passed through and we had only to contend with torrential rain and gusty wind. Once we were through this swath of fury, the clouds dispersed and we crossed dry, sun-drenched terrain all the way to Denver.
Jumat, 25 Mei 2012
Midwest Mountain Lions
Having once inhabited most of the United States, mountains lions were extirpated from eastern and central portions of our country by the early 20th Century; an exception was the Florida panther, which managed to survive in the dense vegetation of the Everglades and adjacent cypress swamps. Throughout most of the 1900s, the easternmost populations of cougars (other than the Florida panther) were in West Texas and in the Black Hills of western South Dakota.
However, over the past decade, sightings of mountains lions have increased signficantly across the American Midwest. Almost all of the confirmed cases have been males, presumably banished from their home range by other dominant males; indeed, cougars are territorial and field studies have revealed that the home range of adult males is in the neighborhood of 100-300 square miles. While 5 mountain lions inhabited the Pine Ridge Escarpment of western Nebraska in 2004, 30 were documented by 2011, including females and cubs. Sightings in Kansas, Missouri, Iowa, Minnesota and Wisconsin have involved male cougars that are thought to have wandered eastward from South Dakota and western Nebraska (though some may have arrived from Colorado via the Arkansas River corridor). One famous case involved a male that wandered through Minnesota and Wisconsin in 2009-2010 and ended up getting killed in Connecticut in 2011. Here in Missouri, there have been at least 29 cougar sightings since 1994, though, in some cases, multiple sightings of the same cat may have occurred. Since mountain lions are secretive and primarily nocturnal, an accurate estimate of Midwest wanderers is very difficult to obtain and it is likely that more pass through this region than some human residents might care to imagine; on the other hand, livestock loss to cougars has been minimal since these travelers seem to favor small mammals and the occasional deer.
Of course, unless females begin to follow the nomadic males from mountainous areas of the West, breeding populations will not become established in the Heartland. The increasingly common sightings in recent decades surely reflects the growth of human populations throughout the Mountain West, depriving these predators of their natural habitat and forcing males to head east, following river channels across the Great Plains. Any excitement associated with the opportunity to observe these magnificent cats in the Midwest is tempered by the knowledge that we have driven them from their modern homeland and that they are returning to an ancient homeland that has forever changed. Whether they will be welcomed or persecuted remains to be seen.
However, over the past decade, sightings of mountains lions have increased signficantly across the American Midwest. Almost all of the confirmed cases have been males, presumably banished from their home range by other dominant males; indeed, cougars are territorial and field studies have revealed that the home range of adult males is in the neighborhood of 100-300 square miles. While 5 mountain lions inhabited the Pine Ridge Escarpment of western Nebraska in 2004, 30 were documented by 2011, including females and cubs. Sightings in Kansas, Missouri, Iowa, Minnesota and Wisconsin have involved male cougars that are thought to have wandered eastward from South Dakota and western Nebraska (though some may have arrived from Colorado via the Arkansas River corridor). One famous case involved a male that wandered through Minnesota and Wisconsin in 2009-2010 and ended up getting killed in Connecticut in 2011. Here in Missouri, there have been at least 29 cougar sightings since 1994, though, in some cases, multiple sightings of the same cat may have occurred. Since mountain lions are secretive and primarily nocturnal, an accurate estimate of Midwest wanderers is very difficult to obtain and it is likely that more pass through this region than some human residents might care to imagine; on the other hand, livestock loss to cougars has been minimal since these travelers seem to favor small mammals and the occasional deer.
Of course, unless females begin to follow the nomadic males from mountainous areas of the West, breeding populations will not become established in the Heartland. The increasingly common sightings in recent decades surely reflects the growth of human populations throughout the Mountain West, depriving these predators of their natural habitat and forcing males to head east, following river channels across the Great Plains. Any excitement associated with the opportunity to observe these magnificent cats in the Midwest is tempered by the knowledge that we have driven them from their modern homeland and that they are returning to an ancient homeland that has forever changed. Whether they will be welcomed or persecuted remains to be seen.
Senin, 16 April 2012
Long-Billed Curlews
While crossing the stormy Plains yesterday afternoon, I encountered a small flock of long-billed curlews, attempting to fly into the teeth of an icy north wind. After wintering along the western Gulf Coast, in South Texas, in Southern California or in Mexico, this largest American shorebird returns to grasslands of the High Plains, Great Basin and Columbia Plateau for the warmer months.
Once on their breeding grounds, couples engage in courtship rituals, including dances, looping flights and preliminary nest site scooping by the male. The female eventually selects one of his open ground sites, engages in additional scooping and collects a variety of plant materials to place in the floor of the depression. Four eggs are deposited and incubated by both parents; like many game birds, the young are able to move about and feed soon after hatching and are attended by both parents for a week or so. Thereafter, the female parent departs to join other wayward mothers and juveniles in large feeding flocks while the father stays to watch over the youngsters until they are fledged. The long, down-curved bill of this curlew is used to probe mudflats, wet meadows and sandy shallows for a variety of invertebrates (worms, insect larvae, shrimp, sand crabs) and small amphibians; they may also snare grasshoppers, crickets and other insects from the grass and occasionally consume the eggs of other prairie birds.
Once common in parts of the Eastern U.S., long-billed curlews have retreated westward due to over-hunting and habitat loss to agriculture; fortunately, the western populations seem to have stabilized but remain sensitive to the health of shortgrass ecosystems. Small numbers of long-billed curlews may turn up on Atlantic beaches during the fall and winter months where they can be distinguished from whimbrels by the curlew's larger size, longer bill and unstriped crown and from the occasional Eurasian curlew by the latter's darker plumage, white rump and heavily streaked breast; the cinnamon wing linings of long-billed curlews also aid identification when this large shorebird is in flight.
Once on their breeding grounds, couples engage in courtship rituals, including dances, looping flights and preliminary nest site scooping by the male. The female eventually selects one of his open ground sites, engages in additional scooping and collects a variety of plant materials to place in the floor of the depression. Four eggs are deposited and incubated by both parents; like many game birds, the young are able to move about and feed soon after hatching and are attended by both parents for a week or so. Thereafter, the female parent departs to join other wayward mothers and juveniles in large feeding flocks while the father stays to watch over the youngsters until they are fledged. The long, down-curved bill of this curlew is used to probe mudflats, wet meadows and sandy shallows for a variety of invertebrates (worms, insect larvae, shrimp, sand crabs) and small amphibians; they may also snare grasshoppers, crickets and other insects from the grass and occasionally consume the eggs of other prairie birds.
Once common in parts of the Eastern U.S., long-billed curlews have retreated westward due to over-hunting and habitat loss to agriculture; fortunately, the western populations seem to have stabilized but remain sensitive to the health of shortgrass ecosystems. Small numbers of long-billed curlews may turn up on Atlantic beaches during the fall and winter months where they can be distinguished from whimbrels by the curlew's larger size, longer bill and unstriped crown and from the occasional Eurasian curlew by the latter's darker plumage, white rump and heavily streaked breast; the cinnamon wing linings of long-billed curlews also aid identification when this large shorebird is in flight.
Minggu, 15 April 2012
Crossing the Storm
After stewing in the warm sector of our latest Pacific storm for 36 hours, enduring periods of heavy rain, intense thunderstorms and interludes of steamy sunshine, we left Columbia this morning, bound for our Littleton, Colorado farm. Having checked the Weather Channel before our departure, we noted that the storm system's upper level low was still centered over western Kansas and that its dry line, responsible for the wealth of tornadoes over the previous 24 hours, was about to reach Kansas City.
Fortunately, the severe weather was down in northeast Oklahoma and we left the balmy air of Missouri as we crossed through a modest band of rain showers and entered cooler, drier air in eastern Kansas. Sunny conditions persisted into central Kansas but once we reached the Smoky Hills Wind Farm, its massive turbines spinning in a strong south wind, a band of clouds appeared across the western horizon. We soon realized that the clouds represented the eastern wall of the storm's low pressure swirl; produced by uplift and rotating counterclockwise around the center of low pressure, the direction of cloud movement changed as we continued west along I-70. Moving northward in central Kansas, the clouds were coming from the west in western Kansas and were drifting southward in eastern Colorado. Finally, as we neared the Front Range, upslope showers developed as a northeast wind from the atmospheric swirl pushed humid air toward the Palmer Divide and Front Range foothills. Rising, cooling and condensing, this upslope flow produced snow showers above 7000 feet and sleety rain on the High Plains.
An eleven hour (800 mile) drive had taken us from balmy, 70 degree F air on the west edge of the storm system to chilly showers of rain and sleet on its western rim. En route, we crossed all of the storm's component air masses and directly witnessed the atmospheric swirl of its central low. What better way to appreciate the structure and power of these massive storm systems?
Fortunately, the severe weather was down in northeast Oklahoma and we left the balmy air of Missouri as we crossed through a modest band of rain showers and entered cooler, drier air in eastern Kansas. Sunny conditions persisted into central Kansas but once we reached the Smoky Hills Wind Farm, its massive turbines spinning in a strong south wind, a band of clouds appeared across the western horizon. We soon realized that the clouds represented the eastern wall of the storm's low pressure swirl; produced by uplift and rotating counterclockwise around the center of low pressure, the direction of cloud movement changed as we continued west along I-70. Moving northward in central Kansas, the clouds were coming from the west in western Kansas and were drifting southward in eastern Colorado. Finally, as we neared the Front Range, upslope showers developed as a northeast wind from the atmospheric swirl pushed humid air toward the Palmer Divide and Front Range foothills. Rising, cooling and condensing, this upslope flow produced snow showers above 7000 feet and sleety rain on the High Plains.
An eleven hour (800 mile) drive had taken us from balmy, 70 degree F air on the west edge of the storm system to chilly showers of rain and sleet on its western rim. En route, we crossed all of the storm's component air masses and directly witnessed the atmospheric swirl of its central low. What better way to appreciate the structure and power of these massive storm systems?
Selasa, 03 April 2012
The Western Ibis
Cousin to the glossy ibis of the Southeastern U.S., the white-faced ibis winters along the Gulf Coast (from Louisiana to Texas), in valley wetlands of central and southern California and in Mexico. While some are permanent residents in these areas, most migrate through the central and western U.S. to breed on freshwater wetlands of the Northern Plains and Intermountain West.
Since wetland conditions tend to vary across the dry country of the Western U.S., these nomadic migrants are opportunistic, choosing their colonial nest sites based on the conditions that they find; for this reason, their numbers in any given area varies widely from year to year. Preferring broad, shallow wetlands with islands of vegetation, white-faced ibis nest in marsh grasses or in low trees along the shore. Both parents incubate the 3-4 eggs and participate in feeding regurgitated insects, worms, amphibians and small fish to the nestlings; the young are fledged within a month and are self sufficient by August.
Known to wander widely in late summer, small flocks of white-faced ibis turn up in the eastern U.S. on occasion but generally return to their traditional wintering grounds by mid autumn. Peak spring migrations across the Great Plains generally occur from mid April to early May and it is then that most of us encounter these attractive birds, stopping to rest and feed on shallow lakes, braided rivers or flooded fields.
Since wetland conditions tend to vary across the dry country of the Western U.S., these nomadic migrants are opportunistic, choosing their colonial nest sites based on the conditions that they find; for this reason, their numbers in any given area varies widely from year to year. Preferring broad, shallow wetlands with islands of vegetation, white-faced ibis nest in marsh grasses or in low trees along the shore. Both parents incubate the 3-4 eggs and participate in feeding regurgitated insects, worms, amphibians and small fish to the nestlings; the young are fledged within a month and are self sufficient by August.
Known to wander widely in late summer, small flocks of white-faced ibis turn up in the eastern U.S. on occasion but generally return to their traditional wintering grounds by mid autumn. Peak spring migrations across the Great Plains generally occur from mid April to early May and it is then that most of us encounter these attractive birds, stopping to rest and feed on shallow lakes, braided rivers or flooded fields.
Sabtu, 24 Maret 2012
Mt. Salina
Having driven across the Great Plains on many occasions, I have come to know the cities and towns, their respective exit numbers and, most importantly, the amenities that they offer for the traveler. In addition, as a naturalist, I have come to recognize these human oases by their surrounding terrain (yes, the Great Plains harbor a mix of topography).
One of these natural landmarks is a small but prominent mesa just east of Salina, Kansas. While it has an elevation of only 1500 feet or so, it rises almost 300 feet above the city and its immediate surroundings. Nameless on the few maps that I have checked, I have christened it Mt. Salina and have noted that this erosional remnant rises south of the Smoky Hill River, near its junction with the Saline River.
While not nearly as majestic as Pikes Peak and other famous landmarks across the American West, this mesa must have played a significant role in guiding early settlers and native Americans to regional settlements and their vital water resource (though I profess no historical knowledge in this regard). As for myself, I am always glad to catch site of Mt. Salina when I head west on I-70, a sign that I have put a significant dent in my journey across the Plains.
One of these natural landmarks is a small but prominent mesa just east of Salina, Kansas. While it has an elevation of only 1500 feet or so, it rises almost 300 feet above the city and its immediate surroundings. Nameless on the few maps that I have checked, I have christened it Mt. Salina and have noted that this erosional remnant rises south of the Smoky Hill River, near its junction with the Saline River.
While not nearly as majestic as Pikes Peak and other famous landmarks across the American West, this mesa must have played a significant role in guiding early settlers and native Americans to regional settlements and their vital water resource (though I profess no historical knowledge in this regard). As for myself, I am always glad to catch site of Mt. Salina when I head west on I-70, a sign that I have put a significant dent in my journey across the Plains.
Minggu, 18 Maret 2012
Ground Turbulence
My regular trips between Missouri and Colorado are usually a bit tiring but today's journey was especially difficult. After leaving Columbia in a balmy haze this morning, I encountered a southwest wind in eastern Kansas which strengthened with every mile to the west, all the way to the Front Range. Though the skies were mostly sunny and I had neither supercells nor snow to complicate my travel, nine hours of bone-jarring turbulence was more than enough.
While the strong wind was my sole problem through eastern and central Kansas, dust plumes and tumbleweed armies posed additional distractions across the dry landscape of the High Plains. Fortunately, no trucks were overturned by the winds and few RV's ventured across the Great Plains today, a wise response to the high wind advisory. Though strong winds are common across this region, today's wind field is especially widespread and is posing a major fire threat from New Mexico and West Texas to Nebraska. Gusty winds along the Front Range have enveloped Denver in a pall of dust and a large wildfire is currently burning in northeast Colorado.
Today's strong winds are the product of a potent low over Wyoming (attached to a deep trough over the western U.S.) and a massive area of high pressure over the eastern States. Counterclockwise winds around the low are combining with clockwise winds at the edge of the high pressure dome, leading to a strong south-southwesterly flow over the Great Plains. The leading edge of the trough is forecast to cross the Rockies overnight and, here in Metro Denver, we'll experience cool, showery weather for the next few days. Meanwhile, as the front moves eastward, these strong winds will precede it, raking the Midwest and igniting thunderstorms as Gulf moisture enters the mix.
While the strong wind was my sole problem through eastern and central Kansas, dust plumes and tumbleweed armies posed additional distractions across the dry landscape of the High Plains. Fortunately, no trucks were overturned by the winds and few RV's ventured across the Great Plains today, a wise response to the high wind advisory. Though strong winds are common across this region, today's wind field is especially widespread and is posing a major fire threat from New Mexico and West Texas to Nebraska. Gusty winds along the Front Range have enveloped Denver in a pall of dust and a large wildfire is currently burning in northeast Colorado.
Today's strong winds are the product of a potent low over Wyoming (attached to a deep trough over the western U.S.) and a massive area of high pressure over the eastern States. Counterclockwise winds around the low are combining with clockwise winds at the edge of the high pressure dome, leading to a strong south-southwesterly flow over the Great Plains. The leading edge of the trough is forecast to cross the Rockies overnight and, here in Metro Denver, we'll experience cool, showery weather for the next few days. Meanwhile, as the front moves eastward, these strong winds will precede it, raking the Midwest and igniting thunderstorms as Gulf moisture enters the mix.
Jumat, 10 Februari 2012
From Snow to Snows
As we left the snowy landscape of Metro Denver yesterday morning, a full moon gleamed above the Front Range. Once past the Palmer Divide, the snow cover gradually diminished and, except for residual drifts along the highway, had disappeared by the time we entered Kansas. However, as I discussed on February 6, the snow blanket reappeared near Wakeeney and then steadily vanished as we descended toward Hays.
For the remainder of our journey, a brown landscape and gray sky set the scene; only the aerial ballets of starlings, the agile swoop of harriers and the reliable presence of red-tails broke the monotony. Then, just east of Russell, Kansas, my first glimpse of snow geese during this "spring" migration season erased my boredom as a wavering flock crossed the bleak winter sky, headed toward their Arctic breeding grounds. A second flock appeared near Salina and a third, much larger flock graced the sky in eastern Kansas.
Darkness negated any sightings in Missouri but, over the next six weeks, I'll hear and see many more flocks of these vocal travelers, the vanguard of our gathering spring. While the season of snow has yet to run it course, snow geese carry the hope of warmer, fragrant and colorful days ahead.
For the remainder of our journey, a brown landscape and gray sky set the scene; only the aerial ballets of starlings, the agile swoop of harriers and the reliable presence of red-tails broke the monotony. Then, just east of Russell, Kansas, my first glimpse of snow geese during this "spring" migration season erased my boredom as a wavering flock crossed the bleak winter sky, headed toward their Arctic breeding grounds. A second flock appeared near Salina and a third, much larger flock graced the sky in eastern Kansas.
Darkness negated any sightings in Missouri but, over the next six weeks, I'll hear and see many more flocks of these vocal travelers, the vanguard of our gathering spring. While the season of snow has yet to run it course, snow geese carry the hope of warmer, fragrant and colorful days ahead.
Senin, 06 Februari 2012
High Plains Upslope
On my frequent travels between Missouri and Colorado, I have often noticed that, following a snowstorm, the Wakeeney, Kansas, area receives more snow than areas to its west or east on I-70. Assuming this must represent an upslope phenomenon, a reflection of the local topography, I examined a map of the region after yesterday's journey reinforced my past observations.
In fact, Wakeeney sits on the east edge of the High Plains at the west end of a topographic wedge in which the elevation is gradually rising from east to west. A prominent ridge just south of Hays, Kansas, is an erosional remnant of the High Plains, dividing the watersheds of the Smoky Hill River, to its south, from that of Big Creek to its north. In similar fashion, though not as visible from I-70, another eastward extension of the High Plains divides the Big Creek watershed from that of the Saline River, to the north of that ridge. Both of these ridges merge near Wakeeney and the rolling terrain between them climbs from 2000 feet at Hays to about 2450 feet at Wakeeney, yielding an upslope terrain that concentrates its orographic precipitation near the latter city; this scenario develops whenever easterly winds sweep Gulf moisture westward toward the High Plains.
Upsloping air cools and condenses, dropping its cargo of rain or snow. Such orographic weather events are common along mountain ranges, producing vital snowpacks in many regions and moist, forested retreats in the "sky islands" of desert areas. The upsloping terrain near Wakeeney is repeated at many other sites across the Great Plains, where a series of escarpments produce stair-like transitions from the lower, tallgrass zone on the east to the higher, shortgrass ecosystem of the High Plains. In addition, similar escarpments border the High Plains to the north, west and south, yielding upslope funnels in those regions as well; examples include the Pine Ridge Escarpment of western Nebraska and the Palmer Divide in eastern Colorado.
In fact, Wakeeney sits on the east edge of the High Plains at the west end of a topographic wedge in which the elevation is gradually rising from east to west. A prominent ridge just south of Hays, Kansas, is an erosional remnant of the High Plains, dividing the watersheds of the Smoky Hill River, to its south, from that of Big Creek to its north. In similar fashion, though not as visible from I-70, another eastward extension of the High Plains divides the Big Creek watershed from that of the Saline River, to the north of that ridge. Both of these ridges merge near Wakeeney and the rolling terrain between them climbs from 2000 feet at Hays to about 2450 feet at Wakeeney, yielding an upslope terrain that concentrates its orographic precipitation near the latter city; this scenario develops whenever easterly winds sweep Gulf moisture westward toward the High Plains.
Upsloping air cools and condenses, dropping its cargo of rain or snow. Such orographic weather events are common along mountain ranges, producing vital snowpacks in many regions and moist, forested retreats in the "sky islands" of desert areas. The upsloping terrain near Wakeeney is repeated at many other sites across the Great Plains, where a series of escarpments produce stair-like transitions from the lower, tallgrass zone on the east to the higher, shortgrass ecosystem of the High Plains. In addition, similar escarpments border the High Plains to the north, west and south, yielding upslope funnels in those regions as well; examples include the Pine Ridge Escarpment of western Nebraska and the Palmer Divide in eastern Colorado.
Minggu, 18 Desember 2011
A Sherbet Sunrise
Yesterday morning, as I left Denver under clear, cold skies, I was treated to a spectacular sunrise on the High Plains. The mellow but brilliant colors reminded me of the rainbow sherbet that I often enjoyed as a child (and still do on occasion). Low, flat clouds had taken on a raspberry glow while a swath of lemon yellow stretched across the horizon, fading to lime green at the fringes. As sunrise approached, the pale yellow evolved to a deep orange off to the southeast, marking the site where the sun would soon appear.
Humans have always been inspired by the sunrise and, for early man, it surely brought hope after the long, frigid winter nights. Even today, the sun's return is especially welcome after the extended periods of darkness that typify the season. More than signifying the recovery of light and heat (what little is provided by a low winter sun), the colorful display offers reassurance that nature's cycle will persevere.
Some may feel that I am overstating the significance of a sunrise to such intelligent creatures as human beings. But I suspect that we all carry collective memories from our distant ancestors, perhaps imprinted in our genetic code, that trigger deep-seated emotions in response to certain natural events. Early in our history, this revelation was vital to combat despair and, even today, it lingers in our soul for the same purpose.
Humans have always been inspired by the sunrise and, for early man, it surely brought hope after the long, frigid winter nights. Even today, the sun's return is especially welcome after the extended periods of darkness that typify the season. More than signifying the recovery of light and heat (what little is provided by a low winter sun), the colorful display offers reassurance that nature's cycle will persevere.
Some may feel that I am overstating the significance of a sunrise to such intelligent creatures as human beings. But I suspect that we all carry collective memories from our distant ancestors, perhaps imprinted in our genetic code, that trigger deep-seated emotions in response to certain natural events. Early in our history, this revelation was vital to combat despair and, even today, it lingers in our soul for the same purpose.
Selasa, 13 Desember 2011
The Wichita Mountains
Rising from the flat terrain of southern Oklahoma, northwest of Lawton, ridges of igneous and metamorphic rock trend northwest to southeast. Thirty miles long, these rock formations originated in a rift zone that developed from the late Precambrian Era into the Cambrian Period, some 550-600 million years ago. Though the rifting process was aborted, plutons of granite, intrusions of gabbro and deposits of rhyolite were encased within and atop the surrounding crust and, over the next 20 million years, were covered by layers of younger Paleozoic sediments.
During the Pennsylvanian Period, about 325 million years ago, the continents began to merge into Pangea. The collision of North America and Africa crumpled up the Southern Appalachians and the docking of South America extended that collision zone toward the west, lifting the Ouachita and Wichita Mountains. Erosion coincided with this uplift and continues today; having carried away the overlying and encasing sediments, wind and water have left behind outcrops of the ancient rock that formed within the Cambrian rift. Of course, the ridges of the Wichita Mountains, like all ranges on this planet, will eventually wear down to a level plain, their aprons of debris carried off to the sea or dispersed by the wind.
Wichita Mountains NWR protects a portion of this scenic landscape, providing habitat for bison, elk and the more common wildlife of southern Oklahoma. Several of the peaks rise above 2400 feet, offering a cool retreat during the summer months and attracting a wide variety of birds to their oak woodlands. From I-44, about 8 miles north of Lawton, head west on Route 49; the refuge will be approximately 12 miles ahead.
During the Pennsylvanian Period, about 325 million years ago, the continents began to merge into Pangea. The collision of North America and Africa crumpled up the Southern Appalachians and the docking of South America extended that collision zone toward the west, lifting the Ouachita and Wichita Mountains. Erosion coincided with this uplift and continues today; having carried away the overlying and encasing sediments, wind and water have left behind outcrops of the ancient rock that formed within the Cambrian rift. Of course, the ridges of the Wichita Mountains, like all ranges on this planet, will eventually wear down to a level plain, their aprons of debris carried off to the sea or dispersed by the wind.
Wichita Mountains NWR protects a portion of this scenic landscape, providing habitat for bison, elk and the more common wildlife of southern Oklahoma. Several of the peaks rise above 2400 feet, offering a cool retreat during the summer months and attracting a wide variety of birds to their oak woodlands. From I-44, about 8 miles north of Lawton, head west on Route 49; the refuge will be approximately 12 miles ahead.
Senin, 12 Desember 2011
December on the Plains
As I left Columbia this morning, a silver dollar moon beamed in the western sky, illuminating the predawn landscape. By the time I reached western Missouri, the pink rays of sunrise were reflecting from a deck of high, puffy clouds and several flocks of snow geese wavered southward above the rolling farmlands.
Once I entered Kansas a thick layer of clouds covered the sky but rusty grasses of the Flint Hills added color to an otherwise drab landscape. Numerous red-tailed hawks perched along the highway, restless Canada geese moved among the crop fields and a lone Cooper's hawk streaked across the roadway, headed for a valley woodland. The first snow banks appeared west of Hays and snow cover waxed and waned for the rest of my trip, peaking near Colby, Kansas, and along the base of the Front Range. On the High Plains, flocks of meadowlarks, horned larks and longspurs drifted across the fields, ring-necked pheasants foraged along the highway and northern harriers flapped low above the crop stubble, hunting for rodents. Finally, north of Limon, a few herds of pronghorn, the only wild mammals encountered on my journey, roamed the grasslands of the Palmer Divide.
As I approached Denver, the Front Range was backlit by a brilliant sunset and a northeast wind was producing both upslope haze across the city and lowering clouds across the wall of peaks. A significant snowfall is not forecast for the Metro Area but one never knows along this corridor of fickle and ever-changing weather. It is, after all, December.
Once I entered Kansas a thick layer of clouds covered the sky but rusty grasses of the Flint Hills added color to an otherwise drab landscape. Numerous red-tailed hawks perched along the highway, restless Canada geese moved among the crop fields and a lone Cooper's hawk streaked across the roadway, headed for a valley woodland. The first snow banks appeared west of Hays and snow cover waxed and waned for the rest of my trip, peaking near Colby, Kansas, and along the base of the Front Range. On the High Plains, flocks of meadowlarks, horned larks and longspurs drifted across the fields, ring-necked pheasants foraged along the highway and northern harriers flapped low above the crop stubble, hunting for rodents. Finally, north of Limon, a few herds of pronghorn, the only wild mammals encountered on my journey, roamed the grasslands of the Palmer Divide.
As I approached Denver, the Front Range was backlit by a brilliant sunset and a northeast wind was producing both upslope haze across the city and lowering clouds across the wall of peaks. A significant snowfall is not forecast for the Metro Area but one never knows along this corridor of fickle and ever-changing weather. It is, after all, December.
Rabu, 24 Agustus 2011
Crescent Lake NWR
Crescent Lake NWR, in Nebraska's western panhandle, is certainly one of our more remote National Wildlife Refuges. Take your pick: 28 miles north of Oshkosh (on US 26, northwest of Ogallala) via a winding, sand-gravel road or 28 miles south of Lakeside (on Route 2, east of Alliance) via a single lane of asphalt; during my three hour tour I encountered only a refuge employee in his pickup and the driver of a cattle truck. Whatever route you take, the visit will be well worth your effort (just make sure you have plenty of gas in the tank).
Stretching across 46,000 acres in the westernmost section of Nebraska's famous sandhills ecosystem, Crescent Lake National Wildlife Refuge protects a chain of lakes and wetlands that lie in valleys between the grass-covered dunes. Established in 1931, the refuge provides nesting habitat, wintering grounds or a migration reststop for at least 279 bird species. Nesting birds of note include eared and western grebes, American bitterns, tundra swans, canvasbacks, bald eagles, sharp-tailed grouse, black-necked stilts, American avocets, long-billed curlews, Wilson's phalaropes, black terns, burrowing owls, marsh wrens and blue grosbeaks, among many other species. High Plains grassland residents, best observed along the roadways, include northern harriers, Swainson's hawks, American kestrels, dickcissels, lark sparrows, lark buntings, vesper sparrows, grasshopper sparrows, bobolinks, yellow-headed blackbirds and both eastern and western meadowlarks. Flocks of American white pelicans soared above the refuge yesterday morning and I also encountered a large number of white-faced ibis; late summer is also ideal for shorebird watching and Crescent Lake NWR attracts a wide variety of resident and migrant species.
In addition to the birdlife, this scenic preserve is home to coyotes, swift fox, white-tailed and mule deer, pronghorns, muskrats, kangaroo rats and an excellent variety of reptiles and amphibians; yellow mud turtles inhabit the preserve and bullsnakes are often encountered on the roadways. Of interest, Crescent Lake itself actually lies just south of the refuge boundary and is protected by the State of Nebraska; efforts to establish a sandhills wilderness area, just east of the refuge, are currently under consideration.
Stretching across 46,000 acres in the westernmost section of Nebraska's famous sandhills ecosystem, Crescent Lake National Wildlife Refuge protects a chain of lakes and wetlands that lie in valleys between the grass-covered dunes. Established in 1931, the refuge provides nesting habitat, wintering grounds or a migration reststop for at least 279 bird species. Nesting birds of note include eared and western grebes, American bitterns, tundra swans, canvasbacks, bald eagles, sharp-tailed grouse, black-necked stilts, American avocets, long-billed curlews, Wilson's phalaropes, black terns, burrowing owls, marsh wrens and blue grosbeaks, among many other species. High Plains grassland residents, best observed along the roadways, include northern harriers, Swainson's hawks, American kestrels, dickcissels, lark sparrows, lark buntings, vesper sparrows, grasshopper sparrows, bobolinks, yellow-headed blackbirds and both eastern and western meadowlarks. Flocks of American white pelicans soared above the refuge yesterday morning and I also encountered a large number of white-faced ibis; late summer is also ideal for shorebird watching and Crescent Lake NWR attracts a wide variety of resident and migrant species.
In addition to the birdlife, this scenic preserve is home to coyotes, swift fox, white-tailed and mule deer, pronghorns, muskrats, kangaroo rats and an excellent variety of reptiles and amphibians; yellow mud turtles inhabit the preserve and bullsnakes are often encountered on the roadways. Of interest, Crescent Lake itself actually lies just south of the refuge boundary and is protected by the State of Nebraska; efforts to establish a sandhills wilderness area, just east of the refuge, are currently under consideration.
Sabtu, 30 Juli 2011
Driving back through Time
Leaving Denver this morning, I headed east across the High Plains of eastern Colorado which have a veneer of late Tertiary sediments (about 5-30 million years old), eroded from the Rockies or blown eastward from volcanoes of the Western U.S. Now sculpted into broad uplands and valleys across the Colorado Piedmont, these deposits form loosely compacted strata that overly Cretaceous shale and sandstone; the latter sediments, some 100 million years old, are upturned as a hogback along the base of the Front Range and are exposed across the "lowlands" of the South Platte Valley.
By the time I reached central Kansas, the relatively young Tertiary sediments had disappeared and Cretaceous limestones lay just beneath the soil; these chalks and "post-rocks" were deposited in a broad, shallow sea, which stretched from the Texas coast to northwest Canada about 100 million years ago (MYA). Just east of Junction City, I-70 climbs into the Flint Hills, composed of Permian strata (about 250 million years old); these scenic ridges are the northern end a a Permian swath that stretches southwestward to the Permian Basin of West Texas. It was during the Permian Period that Earth's continents merged to form Pangea, forcing up the Southern Appalachians as North American collided with Africa.
In easternmost Kansas and western Missouri, Pennsylvanian rocks are exposed along rivers and roadcuts; deposited about 300 MYA, they represent a time when fern forests dominated the globe, home to early reptiles and giant amphibians. Nearing Columbia, outcrops of Mississipian limestone appear along the highway; deposited in shallow seas, some 325 MYA, this bedrock now yields the karst topography of gorges, caves, springs and sinkholes that characterize Central Missouri. Over the course of 11 hours, I covered 700 miles and traveled back through 300 million years of geologic history.
By the time I reached central Kansas, the relatively young Tertiary sediments had disappeared and Cretaceous limestones lay just beneath the soil; these chalks and "post-rocks" were deposited in a broad, shallow sea, which stretched from the Texas coast to northwest Canada about 100 million years ago (MYA). Just east of Junction City, I-70 climbs into the Flint Hills, composed of Permian strata (about 250 million years old); these scenic ridges are the northern end a a Permian swath that stretches southwestward to the Permian Basin of West Texas. It was during the Permian Period that Earth's continents merged to form Pangea, forcing up the Southern Appalachians as North American collided with Africa.
In easternmost Kansas and western Missouri, Pennsylvanian rocks are exposed along rivers and roadcuts; deposited about 300 MYA, they represent a time when fern forests dominated the globe, home to early reptiles and giant amphibians. Nearing Columbia, outcrops of Mississipian limestone appear along the highway; deposited in shallow seas, some 325 MYA, this bedrock now yields the karst topography of gorges, caves, springs and sinkholes that characterize Central Missouri. Over the course of 11 hours, I covered 700 miles and traveled back through 300 million years of geologic history.
Minggu, 22 Mei 2011
A Parade of Supercells
Heading east in central Kansas last evening, I witnessed a parade of supercells, spaced across the eastern horizon; each half-again as tall as Mt. Everest, they reflected the setting sun. As I grew closer to this spectacle, the gaps began to close with new thunderstorms as outflow from the parent cells created lift. Soon, a massive wall of chaos loomed across my path; fortunately, I had made plans to spend the night west of the storms.
Safely in my motel room, I tuned into the Weather Channel and found that an interrupted line of severe thunderstorms, some with tornadoes, stretched from East Texas to Minnesota. I was also entertained by two of the Channel's expert stuntmen, doing exactly what they tell us not to do: standing in the dark near intense storms, looking for tornadoes with the aid of limited radar and night-vision glasses. Fortunately, no on-air mishaps.
The culprit for the severe weather was a massive, upper level low, parked over the Northern Plains. Still in place today, it will spawn new waves of storms as dry air from the west is swept into humid air moving up from the Gulf. Indeed, as I approached eastern Kansas this morning, puffy clouds were lining up above the hazy surface air, ready to ignite severe storms as afternoon heating intensifies. And don't worry, those courageous storm chasers are still in the path of the storms, ready to bring us live scenes of destruction.
Safely in my motel room, I tuned into the Weather Channel and found that an interrupted line of severe thunderstorms, some with tornadoes, stretched from East Texas to Minnesota. I was also entertained by two of the Channel's expert stuntmen, doing exactly what they tell us not to do: standing in the dark near intense storms, looking for tornadoes with the aid of limited radar and night-vision glasses. Fortunately, no on-air mishaps.
The culprit for the severe weather was a massive, upper level low, parked over the Northern Plains. Still in place today, it will spawn new waves of storms as dry air from the west is swept into humid air moving up from the Gulf. Indeed, as I approached eastern Kansas this morning, puffy clouds were lining up above the hazy surface air, ready to ignite severe storms as afternoon heating intensifies. And don't worry, those courageous storm chasers are still in the path of the storms, ready to bring us live scenes of destruction.
Rabu, 11 Mei 2011
The Pine Ridge Escarpment
Curving through northwestern Nebraska and into the southwest corner of South Dakota, the Pine Ridge Escarpment, rising to 5000 feet, divides the watersheds of the White River, to its north, and the Niobrara River, to its south. Like the Gangplank, west of Cheyenne, and the Palmer Divide, between Denver and Colorado Springs, this ridge is an erosional remnant, molded from Tertiary sediments during the cool, wet climate of the Pleistocene.
Capped with Miocene sandstone of the Arikaree Group, the north-facing, 100 mile long escarpment represents the edge of the High Plains, which stretch away to the south. North of the ridge, the terrain drops into the Missouri Plateau, where the White River and its tributaries have produced badlands in the older sediments of the Oligocene (the White River Group). West of Pine Ridge, the Hat Creek Breaks represent similar geologic strata, rising between the watersheds of the Cheyenne and Upper Niobrara Rivers.
Named for the groves of ponderosa pine that cloak its summit and northern flank, Pine Ridge also harbors a mix of junipers and drought-tolerant shrubs (snowberry, skunkbush, chokecherry, sumac), which attract bighorn sheep, elk, mule deer, porcupines and wild turkey; predators include coyotes, bobcats and mountain lions. Naturalists can most easily explore this ridge at Ft. Robinson State Park, west of Crawford, and Chadron State Park, south of Chadron; more adventurous visitors might set their sights on the Soldier Creek Wilderness Area, WNW of Ft. Robinson. The Toadstool Geologic Park, NNW of Crawford, offers a spectacular array of Oligocene formations, exposed within the Oglala National Grassland.
Capped with Miocene sandstone of the Arikaree Group, the north-facing, 100 mile long escarpment represents the edge of the High Plains, which stretch away to the south. North of the ridge, the terrain drops into the Missouri Plateau, where the White River and its tributaries have produced badlands in the older sediments of the Oligocene (the White River Group). West of Pine Ridge, the Hat Creek Breaks represent similar geologic strata, rising between the watersheds of the Cheyenne and Upper Niobrara Rivers.
Named for the groves of ponderosa pine that cloak its summit and northern flank, Pine Ridge also harbors a mix of junipers and drought-tolerant shrubs (snowberry, skunkbush, chokecherry, sumac), which attract bighorn sheep, elk, mule deer, porcupines and wild turkey; predators include coyotes, bobcats and mountain lions. Naturalists can most easily explore this ridge at Ft. Robinson State Park, west of Crawford, and Chadron State Park, south of Chadron; more adventurous visitors might set their sights on the Soldier Creek Wilderness Area, WNW of Ft. Robinson. The Toadstool Geologic Park, NNW of Crawford, offers a spectacular array of Oligocene formations, exposed within the Oglala National Grassland.
Selasa, 26 April 2011
Flint Hills NWR
Mention the Flint Hills of eastern Kansas and most of us picture broad, grass-covered ridges with narrow, wooded valleys, grazed by cattle and patrolled by raptors. So, as I headed for the Flint Hills National Wildlife Refuge, southeast of Emporia, I expected tallgrass prairie, bison herds, coyotes and upland songbirds.
In fact, like most preserves in the National Wildlife Refuge System, Flint Hills was established to protect habitat for migrating waterfowl. Stretching along the Neosho River floodplain, this attractive refuge offers a mix of wetland habitats which attract a wide variety of wildlife. In addition to the waterfowl, one can expect to see herons, egrets, gulls, shorebirds, wild turkeys, bald eagles, white-tailed deer and a host of reptiles and amphibians; of course, the numerous insects attract a diverse population of resident and migrant songbirds.
Accessed by short trails and an extensive network of gravel roads, the Flint Hills refuge covers the Neosho River floodplain from the town of Neosho Rapids to the backwaters of the John Redmond Reservoir. To reach the preserve from Emporia, head east on I-35 for approximately 5 miles, turn south on Route 130 and proceed 3 miles to the entrance; much of the refuge is closed to the public from November 1 through March 1 but is otherwise open from dawn to dusk.
In fact, like most preserves in the National Wildlife Refuge System, Flint Hills was established to protect habitat for migrating waterfowl. Stretching along the Neosho River floodplain, this attractive refuge offers a mix of wetland habitats which attract a wide variety of wildlife. In addition to the waterfowl, one can expect to see herons, egrets, gulls, shorebirds, wild turkeys, bald eagles, white-tailed deer and a host of reptiles and amphibians; of course, the numerous insects attract a diverse population of resident and migrant songbirds.
Accessed by short trails and an extensive network of gravel roads, the Flint Hills refuge covers the Neosho River floodplain from the town of Neosho Rapids to the backwaters of the John Redmond Reservoir. To reach the preserve from Emporia, head east on I-35 for approximately 5 miles, turn south on Route 130 and proceed 3 miles to the entrance; much of the refuge is closed to the public from November 1 through March 1 but is otherwise open from dawn to dusk.
Senin, 25 April 2011
Tornado Central
Last Friday, during my road trip to Oklahoma, a swath of severe, tornadic thunderstorms developed across the southeastern corner of that State. While I was well to the north and west of the storms, their cloudtops loomed to the southeast and I was treated to a few hours of weather coverage by the meteorologists of Oklahoma City.
Since their metropolitan area is second only to Clearwater, Florida, in its susceptibility to tornadoes, these meteorologists are exceptionally knowledgeable about the dynamics of these storms and provide coverage that is both educational and entertaining. Combining information from onsight storm chasers (mapped by GPS on one station) and the latest storm imaging technology, these enthusiatic forecasters keep the citizens of Oklahoma well informed; based on the scientific detail of their discussions, it is also clear that they are speaking to an engaged populace that respects, understands and heeds their advice.
Most televised weather reports focus on the severity and direction of dangerous storms, providing information that has been invaluable in saving lives; the coverage from Oklahoma City goes well beyond this vital warning system, offering insight into factors that generate, sustain or weaken these atmospheric monsters. For those of us who are fascinated by the weather, their expert coverage of tornadic thunderstorms is a thrilling, if unfortunate, experience.
Since their metropolitan area is second only to Clearwater, Florida, in its susceptibility to tornadoes, these meteorologists are exceptionally knowledgeable about the dynamics of these storms and provide coverage that is both educational and entertaining. Combining information from onsight storm chasers (mapped by GPS on one station) and the latest storm imaging technology, these enthusiatic forecasters keep the citizens of Oklahoma well informed; based on the scientific detail of their discussions, it is also clear that they are speaking to an engaged populace that respects, understands and heeds their advice.
Most televised weather reports focus on the severity and direction of dangerous storms, providing information that has been invaluable in saving lives; the coverage from Oklahoma City goes well beyond this vital warning system, offering insight into factors that generate, sustain or weaken these atmospheric monsters. For those of us who are fascinated by the weather, their expert coverage of tornadic thunderstorms is a thrilling, if unfortunate, experience.
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