Monday, November 23, 2009

Blue Grama Grass

In the cloudless sky the September sun burned the land with its fiery ring, branding all living things in the desert whether capable of conscious thought or driven only by the instinct of survival. The rains had stopped weeks ago and now Bina trudged an unmarked path between bald earth and the occasional carpet of the flag like blue grama grass.

Blue Grama is a perennial grass native to the Trans-Pecos. It grows in the hot lowlands of the Chihuahua Desert to the high forested areas of the mountain peaks. It grows throughout North America from Alberta and Manitoba to the Rocky Mountains, Great Plains and Midwest, thriving in a broad range of topography and soil types.
The plant height rarely exceeds 15 inches but the roots can grow as deep as five feet and outward as much as 16 inches, watering and aerating the soils as it burrows. The grass is graze, drought and cold resistant. It offers high protein for livestock tends not to freeze and uses water extensively when available but is capable of going dormant during low or no water conditions.

One way the Blue Grama propogates is with seeds and does best when they are dispersed by wind, birds, insects or mammals beyond the root reach of neighboring adult plants, as adult plants tend to exploit moisture in the seedling’s root zone.
But more often, Blue Grama propagates via a process known as vegetative reproduction. Tiny stems at the base of the plant known as tillers can produce multiple stems and thick tuffs with bushy seed heads from a single seedling indefinitely.

Vegetative Reproduction is more an expansion of biomass of the individual plant rather than the creation of a new organism. The tillers at the base of the plants are new individuals except they are clones, new in every aspect, except genetically. How this process appears to reset the aging clock remains a mystery.

Friday, November 20, 2009

Santa Elena Canyon

Bina and the River that Saved Her

They called her Bina, the Apache name for music maker. She had been playing her flute under a cottonwood tree when they muscled her on the bare back of the palomino. She remembered the taught flank muscles of the horse flexing between her legs as a dark arm wrapped around her, finger nails piercing her side. They galloped across the moon lit desert south toward the river and now three years later she glanced one final time at the mouth of the canyon and the raging waters that had set her free.

The geography of the Big Bend region of Texas over the past 250 million years was formed by a series of compression, volcanism and tension events that created mountain terrain which lent itself to a high degree of erosion. Rapid run-off and flash flooding after thunderstorms is the strongest form of erosion but erosion by way of naturally occurring corrosive chemicals like carbonic acid is also a powerful agent in the geological formation of the area. Calcite which forms the bulk of the limestone in the Big Bend is especially susceptible to break down by carbonic acid.

The formative period of the Santa Elena Canyon likely began about two million years ago, a relatively short period in Earth’s geologic time. The cliffs of the eight mile long, 1500 foot deep canyon run along a fault line. The effect of running water, carbonic acid and the oxygen of water corroding the iron sulfate in the igneous rocks of the canyon, coupled with fault line mechanics eroded and cut deep into the earth’s crust and formed this canyon segment in the watercourse of the Rio Grande.

A series of basin and range topography existed along the future Rio Grande corridor and once the erosion sediment of the higher lands filled the basins, a single flowing conduit linked the Rocky Mountain run-off with the Gulf of Mexico, creating a 1950 mile long waterway and our country’s youngest major river system.

Evidence of pre-historic human settlement in the Santa Elena area date back 10,000 to 12,000 years ago. More recently in the 16th century when Spanish explorers came to the area, they filed written reports with the Spanish Monarchy describing a group of hunter-gatherers known as the Jumano. These tribes may have been related to the Puebloan civilization of Arizona and New Mexico.

Mescalero Apache and Commanche became dominant in the area in the 18th and 19th century. These tribes crossed the Rio Grande both in trade and in warfare with the Spanish and the Jumano.

Thursday, November 12, 2009

Mammatus Clouds

One week into October a line of thunderstorms formed in the Del Norte Mountains of the Trans-Pecos. Dark anvil shaped thunderheads obscured the tops of Mount Ord and Cathedral Mountain. The slanted penetrating rain sheets could be seen from the town below and then as the late evening sun broke though the thinner clouds in the west a blanket of strange sagging gray puffs of laden visible moisture reflected oddly in the dying light and descended into the town’s valley as if a symbol of some new world chaos.

Mammatus or Mammatocumulus clouds are a rare pouch-like cloud structures that form in sinking air usually in the aftermath or on the underside of a thunderstorm where distinct temperature gradients, moisture and wind shear are present and most often when cumulonimbus anvil clouds have formed. The name is derived from the Latin word Mamma meaning udder or breast as some believe these clouds resemble a woman’s breast.

The opaque and lumpy lobes cluster and can cover the sky for miles and each lobe last an average of ten minutes before evaporation dissolves them. They are usually composed of ice crystals or a combination of ice and water.

Inside the cumulonimbus storm clouds, updrafts carry heavy wet air to the top until the momentum is lost and this subsiding air spreads horizontally and accumulates at the base of the cloud. Sagging with water or ice these air-suspended bosoms dangle and cluster in the sky and occasionally form the rare Mammatus cloud.

At least ten theories exist on exactly how they form but because of their rarity and chance sightings observational information remains thin. Much knowledge on micro-physical cloud processes lie on the unknown outside edge of the scientific frontier.