~ Mother Earth ~
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Iceberg
An iceberg (berg is the German word for mountain) is a large piece of ice that has broken off from a glacier or ice shelf and is floating in open water.
An iceberg off Antarctica
Since the density of pure water ice is ca. 920 kg/m³, and that of seawater ca. 1,025 kg/m³, typically, around 90% of the volume of an iceberg is under water, and that portion's shape can be difficult to surmise from looking at what is visible above the surface. This has led to the expression "tip of the iceberg", generally applied to a problem or difficulty, meaning that the problem is only a small manifestation of a larger trouble.
Iceberg - photomontage of what a whole iceberg might look like under water
The mass can be very durable and can easily damage sheet metal. As a result of these factors, icebergs are considered extremely dangerous hazards to shipping. The most famous sinking from an iceberg collision was the destruction of the RMS Titanic on April 14, 1912.
The first to explain the formation of icebergs was the Russian peasant prodigy Mikhailo Lomonosov. In the 20th century, several scientific bodies were established to study and monitor the icebergs. The International Ice Patrol monitors the presence of icebergs in the northern Atlantic Ocean and reports their movements for safety purposes.
An iceberg near Newfoundland
The Antarctic icebergs are monitored by the National Ice Center and are named. The NIC assigns each iceberg larger than 10 miles along at least one axis a name composed of a letter indicating its point of origin and a running number. The letters used are as follows:
A – longitude 0° to 90° W (Bellingshausen Sea, Weddell Sea)
B – longitude 90° W to 180° (Amundsen Sea, Eastern Ross Sea)
C – longitude 90° E to 180° (Western Ross Sea, Wilkesland)
D – longitude 0° to 90° E (Amery Ice Shelf, Eastern Weddell Sea)
Iceberg B15, which calved from the Ross Ice Shelf in 2000 and initially had an area of 11,000 km², was the largest iceberg ever recorded. It broke into two in November 2002. As of December 2004, the largest remaining piece of it, iceberg B-15A, with an area of 3,000 km², is still the largest iceberg (moreover, the largest floating object) on Earth.
Issue #190 -
Queen Charlotte Islands
The Queen Charlotte Islands or Haida Gwaii are an archipelago off the north-west coast of British Columbia, Canada, consisting of two main islands: Graham Island in the North, and Moresby Island in the south.
The islands are separated from the British Columbia mainland on the east by the Hecate Strait. They are separated from Alaska on the north by the Dixon Entrance and from Vancouver Island on the south by the Queen Charlotte Sound.
Queen Charlotte Islands
Some of the land, including the homelands of the Haida people, is protected as Gwaii Haanas National Park Reserve and Haida Heritage Site. The islands are home to an abundance of wildlife, including the largest subspecies of black bear (Ursus americana carlottae) and the subspecies of stoat (Mustela erminea haidarum). The black-tailed deer and raccoon are introduced species which have become abundant.
Haida Gwaii was the site of Kiidk'yaas (meaning "ancient tree"), the only naturally occurring golden Sitka Spruce in the world. This Golden Spruce was sacred to the Haida people as well as a popular tourist attraction. The 300 year old tree was illegally cut down by Grant Hadwin on January 22nd of 1997 as an apparent political protest against the logging companies. Botanists from the University of British Columbia took cuttings from the fallen tree so that this unique form of tree would not be lost forever, and have since offered a number of seedlings to the Haida people to have replanted.
The islands are home to a wide variety of other large native trees, including the Western Redcedar, Nootka Cypress, Shore Pine, Western Hemlock, Mountain Hemlock, and Red alder.
Another rare natural occurrence that was popular amongst tourists to Haida Gwaii was the White Raven. This was a completely albino raven that was often mistaken for an eagle or seagull due to its unusual colouring. The White Raven lived around Port Clements and would commonly be seen taking food hand-outs from locals and visitors alike. It died after making contact with an electrical transformer, temporarily knocking out power to the town and surrounding area.
Some 6,000 people live on the islands. Their economy is resource-based with logging and commercial fishing being the most important. Service industries and government jobs maintain about one-third of the employment rolls. In recent years tourism has started to become a more prominent part of the economy, especially for fishing and tour guides, cycling, camping and adventure tourism.
The archipelago was visited in 1774 by Juan Pérez and in 1778 by Capt. James Cook. In 1787 the islands were surveyed by Capt. George Dixon. The islands were named by Capt. Dixon after one of his ships, the Queen Charlotte, which was named after Queen Charlotte, wife of King George III of the United Kingdom.
The archipelago seems to have escaped much of the glaciation of the last ice age. That, and its subsequent isolation from the mainland, has produced what some call the "Galapagos of the North," a unique biological zone with many unusual animals and plants. Its climate, like that of the rest of the British Columbia and Alaskan coast in the area, is moderated by the Kuroshio Current, and features considerable precipitation and relatively mild temperatures year round.
The artwork known as Haida Gwaii, by Bill Reid, is featured on the reverse side of the Canadian $20 bill. The piece depicts the Spirit of Haida Gwaii in a canoe, accompanied by the mythic messengers. Haida art is also frequently seen on large monumental sized cedar totem poles and even as cartoons in the form of Haida Manga.
Issue #191 -
Mactaquac Dam
The Mactaquac Dam is a Canadian dam built on the Saint John River by NB Power for generating hydroelectricity. Its power house has a capacity of 672 Megawatts with its 6 turbines.
The dam and power house are located approximately 15 km upstream from Fredericton. The dam itself is a rock-fill structure sealed by clay and combined with a concrete spill-way, forming an arch across a narrow section of the river between Kingsclear on the west bank, and Keswick Ridge on the east bank.
Mactaquac Dam
Rising 40 metres in height above the river level, the reservoir (referred to locally as the "head pond") covers 87 square kilometres and extends 96 kilometres upstream, near Woodstock.
The concrete portions of the dam (namely the spill-way) are currently experiencing a problem of expanding concrete. When built, locally quarried greywacke was used as the aggregate and is believed to be responsible for the alkali aggregate reaction expansion. The dam is being monitored and extra maintenance work is being performed, although the spill-way is expected to have a reduced life expectancy.
Kingsclear, NB is also the site of an Atlantic Salmon fish hatchery, located immediately downstream from the dam. The Mactaquac Dam also has a fish ladder to enable migratory fish to move past the obstruction the dam poses.
Flooding of the head pond
Electrical generation began in 1968 after the reservoir had completely filled. The flooding of the valley resulted in the displacement of several thousand residents and land owners, as well as the abandonment of a Canadian National Railway line and numerous local roads and several communities. An historic waterfall was also submerged as the reservoir filled.
The planned town of Nackawic, New Brunswick and the nearby Ste-Anne-de-Nackawic pulp and paper mill were built to accommodate the new reservoir and power opportunities.
Following the success of preserving historic buildings at Upper Canada Village when the upper St. Lawrence River valley was flooded by the Long Sault Dam, the government of New Brunswick created the King's Landing Historical Settlement to save several buildings which would otherwise have been flooded by the Mactaquac headpond.
Issue #192 -
Marsh
In geography, a marsh is a type of wetland, featuring grasses, rushes, reeds, typhas, sedges, and other herbaceous plants (possibly with low-growing woody plants) in a context of shallow water. A marsh is different from a swamp, which is dominated by trees rather than grasses and low herbs. The water of a marsh can be fresh, brackish, or saline. Coastal marshes may be associated with estuaries and along waterways between coastal barrier islands and the inner coast.
Freshwater marsh in Florida
Marshes are critically important wildlife habitat, often serving as breeding grounds for a wide variety of animal life.
Constructed wetlands featuring surface-flow design are usually in the form of a marsh.
Issue #193 -
Royal Gorge
Royal Gorge (also Grand Canyon of the Arkansas) is a canyon on the Arkansas River near Cañon City, Colorado. With a width of 50 feet at its base and a few hundred feet at its top, and a depth of 1,200 feet in places, the 10-mile-long canyon is a narrow, steep crevasse through the granite of Fremont Peak.
Royal Gorge in 1881
About 3 million years ago as the Rocky Mountains rose from the surrounding plains, a small rivulet that would become the Arkansas River rose with them. Over the millennia, it cut a deep channel for itself through the surrounding granite, at a rate of about one foot every 2,500 years. The gorge's peculiar shape, contrasted to broad canyons such as the Grand Canyon, can be attributed to this long, direct erosion through hard rock.
Before European settlement, Native Americans of the Ute people wintered in Royal Gorge for its protection from wind and relatively mild climate. The Comanche, Kiowa, Sioux, and Cheyenne used Royal Gorge on buffalo hunting expeditions as an access point to mountain meadow regions such as South Park Basin.
Colorado's Rocky Mountain region fell under Spanish claims, and conquistador expeditions of the 17th century or fur traders may have seen Royal Gorge in their traversal of the area. The first recorded instance of a European arrival, however, is the Pike expedition of 1806. Zebulon Pike's group built a crude shelter in the gorge and explored the area, descending on horseback over the frozen Arkansas.
Nearby Cañon City was founded in 1860 to exploit possible mineral deposits in the area. Discovery of silver and lead near Leadville in 1877 prompted a race to build rail access to the area. The consequent Royal Gorge Railroad War between crews of the Santa Fe Railroad and the Denver & Rio Grande. Royal Gorge was a bottleneck along the Arkansas too narrow for both rail lines to go through, with no other reasonable access to the South Park area. The Royal Gorge War ended after two years of low-level guerrilla warfare between the two companies after Federal intervention prompted the so-called Treaty of Boston. The D&RG completed its line and leased it for use by the Santa Fe.
Royal Gorge in 1987
In the 1890s Royal Gorge was used as a passenger route for transcontinental rail travel. Four trains per day went through the gorge. Alternate routes through the mountains made Royal Gorge fall from favor for transcontinental use, and passenger trains on the main line stopped in 1967. A sightseeing train now follows the route through the gorge.
In 1929 Cañon City authorized the building of the Royal Gorge Bridge, which at 1,053 feet above the river is the highest suspension bridge over water in the world. The bridge forms the kernel of Royal Gorge Park, a theme park owned and run by the city. Other activities in Royal Gorge area include whitewater rafting and rock climbing.
Issue #194 -
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica, and the only part of that continent that extends outside the Antarctic Circle. It lies in the Western Hemisphere, facing South America. It extends from a line between Cape Adams (Weddell Sea) and a point on the mainland south of Eklund Islands, to Prime Head.
Booth Island and Mount Scott flank the narrow Lemaire Channel on the west side of the Antarctic Peninsula.
The first sighting of Antarctic Peninsula is contested but it apparently occurred in the 1820s. Agreement on this name by the US-ACAN and UK-APC in 1964 resolved a long-standing difference involving use of the American name, Palmer Peninsula, and the British name, Graham Land, for this feature. Graham Land is now restricted to that part of Antarctic Peninsula northward of a line between Cape Jeremy and Cape Agassiz; Palmer Land to the part southward of that line. In Chile, it is officially referred as O´Higgins Land, after the Chilean patriot and Antarctic visionary. The other Spanish countries call it "PenÃnsula Antártica", among them is Argentina: it has got more bases and people there than any other nation.
The peninsula is highly mountainous, its highest peaks rising to approximately 2,800 metres (9,186 feet). These mountains are considered to be a continuation of the Andes of South America, with a submarine spine connecting the two.
Since the peninsula has the mildest climate in Antarctica, the highest concentration of research stations on the continent can be found there, or on the many nearby islands.
Hope Bay is near to the northernmost extremity of the peninsula, which is Prime Head.
Issue #195 -
Flint
Flint (or flintstone) is a hard, sedimentary cryptocrystalline silicate rock with a glassy appearance. Flint is usually dark-grey, blue, black, or deep brown in colour. It occurs chiefly as nodules and masses in chalks and limestones.
Pebble beach made up of flint nodules eroded out of the nearby chalk cliffs, Cape Arkona, Rügen.
A type of chert, this material is one of the most commonly used materials for the manufacture of stone tools during the Stone Age, as it splits into thin, sharp splinters called flakes or blades (depending in the shape) when struck by another hard object (such as a hammerstone made of another material). It remained an essential mineral resource for making fire, including the flintlocks on early firearms, until the close of the 18th century. It was also used extensively from the 13th century until the present day as a material for building stone walls, especially in England.
In Europe, some of the best toolmaking flint has come from Belgium (Obourg, flint mines of Spiennes), the coastal chalks of the English Channel, the Paris Basin, the Sennonian deposits of Rügen and the Jurassic deposits of the Kraków-area in Poland. Flint mining is attested since the Palaeolithic, but became more common since the Neolithic (Michelsberg culture, Funnelbeaker culture).
Issue #196 -
Nunivak Island
Nunivak Island is the second largest island in the Bering Sea, 48 km (30 miles) offshore from the delta of the Yukon and Kuskokwim rivers, at about 60° North latitude. It is 4,450 km² (1.1 million acres) in area. It is volcanic in origin; most of the island is dominated by volcanic plateau 160 m (500 feet) or more above sea level. Tundra is the main landscape feature; the largest trees on Nunivak are dwarf willow trees, most less than 1.2 m (4 feet) tall. More than 40 rivers drain the tundra upland. Brackish lagoons ring the eastern and southern shores, and steep volcanic cliffs dominate the northwest shores.
Nunivak Island in the state of Alaska
At least 89 migratory seabirds and waterfowl have seasonal homes on Nunivak Island, including several endangered and threatened species. Dense summer breeding rookeries are found on all shores of the island and in inland tundra lakes.
Prehistorically, Nunivak was home to a modest herd of caribou, but these were exterminated after the introduction of firearms in the late 19th or early 20th century. United States Fish and Wildlife introduced reindeer and musk ox onto the island in the 1930s and 1940s. Large herds of these animals are maintained by the local Native Corporation of Mekoryuk.
Nunivak is part of the State of Alaska. Most of the island is part of the Yukon Delta National Wildlife Refuge, administered by the U.S. Fish and Wildlife Service.
Muskox on Nunivak Island
Nunivak has only one permanent settlement, Mekoryuk, on the north shore, with about 200 residents. However, in his 1880 census, Ivan Petroff recorded 702 residents in nine villages on the island. An epidemic in 1900 decimated the population of the island. Outmigration keeps the population small and all the current residents live in Mekoryuk. Nearly all the permanent residents of Nunivak are Cup'it Eskimo, who traditionally speak a dialect of Yupik known as Cup'ig. The Cup'ig language is a first language for many older islanders, and is enjoying a dedicated revival among younger islanders as well, although nearly all Nuniwarmiut (Nunivak people) speak English. The people of Nunivak Island still depend to a large degree on subsistence hunting, and also commercial fishing and industrial work on the mainland.
Issue #197 -
Pasture
Pasture is land with lush herbaceous vegetation cover used for grazing of ungulate livestock as part of a farm or ranch. Prior to the advent of mechanized farming, pasture was the primary source of food for cattle and sheep. It is still used extensively, particularly for free range and organic farming, as pasture gives much better living conditions for the animals. Advances in managed intensive grazing (MIG), and improvements in fence technology, led to renewed interest in grazing in the 1990s.
Pasture lands at Kohala, Hawai'i.
Pasture growth can consist of grasses, legumes, or a mixture. Alfalfa, clover, and birdsfoot trefoil are legumes used in intensive pasture management. Many grasses, including ryegrass (Lolium), meadow-grass (Poa), foxtails (Alopecurus), and bents (Agrostis) are used, depending upon conditions, of which soil type, minimum annual temperature, and rainfall amount are most important.
Issue #198 -
Spring
A spring is a point where groundwater flows out of the ground, and is thus where the aquifer surface meets the ground surface. Depending on how constant the source of the water is - rainfall or snowmelt that infiltrates the earth - springs can be ephemeral (intermittent), perennial (continuous) or artesian. When they leave the ground they may form pools or streams.
A natural spring on Mackinaw Island.
Minerals become dissolved in the water as it moves through the underground rocks. This gives the water flavour, and even carbon dioxide bubbles, depending on the nature of the geology. This is why spring water is often bottled and sold as mineral water, although the term is often the subject of deceptive advertising.
Classification
Springs are often classified by the volume of the water they discharge. The largest springs are called "first-magnitude", defined as springs that discharge water at a rate of at least 100 cubic feet per second (2,800 L/s). The scale for spring flow is as follows:
- 1st Magnitude - > 100 ft³/s (2,800 L/s)
- 2nd Magnitude - 10 to 100 ft³/s (280 to 2,800 L/s)
- 3rd Magnitude - 1 to 10 ft³/s (28 to 280 L/s)
- 4th Magnitude - 100 US gal/min (gallons per minute) to 1 ft³/s or 448 US gal/min (6.3 to 28 L/s)
- 5th Magnitude - 10 to 100 gal/min (0.63 to 6.3 L/s)
- 6th Magnitude - 1 to 10 gal/min (63 to 630 mL/s)
- 7th Magnitude - 1 pint to 1 gal/min (8 to 63 mL/s)
- 8th Magnitude - Less than 1 pint/min (8 mL/s)
- 0 Magnitude - no flow (sites of past/historic flow)
Issue #199 -
Black smoker
Black smokers are a type of hydrothermal vent found on the ocean floor. Generally hundreds of meters wide, black smokers are formed when superheated water from below the Earth's crust comes through the ocean floor. They are rich in dissolved minerals from the crust, most notably sulfides, which crystallize to create a chimney-like structure around the vent. When the superheated water in the vent comes in contact with the frigid ocean water, many minerals are precipitated, creating the distinctive black color. The metal sulfides that are deposited can become massive sulfide ore deposits in time.
A black smoker in the Atlantic Ocean
Black smokers were first discovered in 1977 around the Galápagos Islands by the National Oceanic and Atmospheric Administration. They were observed using a small submersible vehicle called Alvin. Today, black smokers are known to exist in the Atlantic and Pacific Oceans, at an average depth of 2100 meters. The temperature of the water they vent can reach 400 °C, but does not boil due to the high pressure it is under at that depth. The water is also extremely acidic, often having a pH value as low as 2.8 — approximately that of vinegar.
Black smoker ecosystem
Although life is very sparse at these depths, black smokers are the center of entire ecosystems. Sunlight is nonexistent, so many organisms — such as archaea and extremophiles — must convert the heat, methane, and sulfur compounds provided by black smokers into energy through a process called chemosynthesis. In turn, more complex life forms like clams and tubeworms feed on these organisms. The organisms at the base of the food chain also deposit minerals into the base of the black smoker, thus completing the life cycle.
Deep sea vent biogeochemical cycle diagram
A bacterium that uses photosynthesis has been found living near a black smoker off the coast of Mexico. At a depth of 2,500 m, no sunlight penetrates the waters. Instead, the bacterium, part of the Green sulfur bacteria family, use the faint glow from the black smoker for photosynthesis making it the first organism found in nature to use a light other than sunlight for the process. (Beatty, et al., 2005)
New and unusual species are constantly being discovered in the neighborhood of black smokers: for instance, the Pompeii worm in the 1980s, and, in 2001, during an expedition to Indian Ocean's Kairei hydrothermal vent field, an armor-plated gastropod. The latter uses iron sulfides (pyrite and greigite) for the structure of its dermal sclerites (hardened body parts), instead of calcium carbonate. The extreme pressure of 2,500 m of water (approximately 25 megapascals) is thought to play a role in stabilizing iron sulfide for biological purposes. This armor plating probably serves as a defense against the venomous radula (teeth) of predatory snails, co-existing in the same community. This snail, which is unique in its kind, has not yet been named.
Issue #200 -
Sargasso Sea
The Sargasso Sea is a region in the Atlantic Ocean.
The sea is an elongated region in the middle of the North Atlantic, and is surrounded by ocean currents. On the west it is bounded by the Gulf Stream; on the north, it is bounded by the North Atlantic Current; on the east, it is bounded by the Canary Current; and on the south, it is bounded by the North Atlantic Equatorial Current. It is, very roughly, 1,125 km wide and 3,220 km long (700 miles wide and 2,000 miles long). It stretches from roughly 70 degrees west to 40 degrees west, and from 25 degrees north to 35 degrees north. Bermuda is located near the western fringes of the sea.
An image of the distribution and size of eel larvae shows the approximate location of the Sargasso Sea.
The Sargasso Sea, which is very salty, is often regarded as being lifeless, though it is home to some seaweed of the genus Sargassum. This seaweed floats en masse on the surface there. The Sargasso Sea also plays a major role in the migration of the European eel; the larvae of the eel hatch there and go to Europe. Later in life, they try to return to the Sargasso to lay eggs there.
Christopher Columbus and his men noted the Sargasso Sea. They brought reports of the large amount of seaweed on the surface. The Carthaginian admiral Himilco had earlier made similar reports after sailing through the Pillars of Hercules: "Many seaweeds grow in the troughs between the waves, which slow the ship like bushes... Here the beasts of the sea move slowly hither and thither, and great monsters swim languidly among the sluggishly creeping ships".
Issue #201 -
Rutile
Rutile is a mineral composed of titanium dioxide, TiO2 one of three distinct titanium dioxide polymorphs:
- rutile, a tetragonal mineral usually of prismatic habit, often twinned;
- anatase or octahedrite, a tetragonal mineral of octahedral habit; and
- brookite, an orthorhombic mineral. Both octahedrite and brookite are relatively rare minerals.
Rutile is often used in paint.
Rutile in trellis texture characteristic of secondary rutile.
Rutile has a sub-conchoidal fracture, is brittle, has a metallic-adamantine lustre, and is generally reddish brown but also sometimes yellowish, bluish, or violet. Rutile derives its name from the Latin rutilus, red, in reference to the deep red color observed in some specimens when viewed by transmitted light. Natural rutile is usually opaque or very dark red. It is transparent to opaque. Rutile may contain up to 10% iron. Rutile is the most stable form of titanium dioxide and is produced at the highest temperatures, with brookite being formed at lower temperatures and octahedrite being formed at still lower temperatures.
Rutile is found as an accessory mineral in some altered igneous rocks, and in certain gneisses and schists. In groups of acicular crystals it is frequently seen penetrating quartz as in the "fléches d'amour" from Grisons, Switzerland. Small rutile needles present in gems are responsible for "star" sapphires, "star" rubies and other "star" gems, an optical phenomenon known as asterism.
Rutilated quartz pendant. The needle-like crystals of rutile can be seen inside the quartz.
Rutile has among the highest refractive indices of any known mineral, and also exhibits high dispersion. These properties have led to several industrial applications, including the production of white paint pigments. Synthetic rutile was first produced in 1948 and is sold under a variety of names. Synthetic rutile can be made in a variety of colors, but not a pure transparent white, being always slightly yellow. A consequence of the high refractive index is an adamantine lustre that leads to an appearance that makes it seldom used in jewellery. It is not very hard, only about 6 on the Mohs hardness scale. The near colorless diamond substitute is sold under the name Titania.
Issue #202 -
Sonoran Desert
The Sonoran Desert (sometimes also called Gila Desert after Gila River) is a North American desert which straddles part of the border between the United States and Mexico and covers large parts of the states of Arizona, California and the Mexican State of Sonora. It is one of the largest and hottest deserts in North America, with an area of 120,000 square miles (311,000 square kilometres). The desert contains a variety of unique plants and animals, such as the saguaro cactus.
Mountains in the Sonoran Desert
The Sonoran Desert wraps around the northern end of the Gulf of California, from northeastern Baja California through southeastern California and southwestern Arizona to western Sonora. It is bounded on the west by the Peninsular Ranges, which separate it from the California chaparral and woodlands and Baja California desert ecoregions of the Pacific slope. To the north, the Sonoran Desert transitions to the cold-winter Mojave, Great Basin, and Colorado Plateau deserts. To the east, the deserts transition to the coniferous Arizona Mountains forests and Sierra Madre Occidental forests at higher elevations. The Sonoran-Sinaloan transition subtropical dry forest marks the transition from the Sonoran Desert to the tropical dry forests of Sinaloa.
Sonoran Desert wildlife
The desert's subregions include the Colorado Desert and Yuma Desert. In the 1951 publication, Vegetation of the Sonoran Desert, Forrest Shreve divided the Sonoran Desert into seven regions according to characteristic vegetation: Lower Colorado Valley, Arizona Upland, Plains of Sonora, Foothills of Sonora, Central Gulf Coast, Vizcaino Region, and Magdalena Region. Many ecologists now consider Shreve's Vizcaino and Magdalena regions, which lie on the western side of the Baja California Peninsula, to be a separate ecoregion, the Baja California desert.
Issue #203 -
Cape Cod Canal
The Cape Cod Canal is a man-made waterway traversing the narrow neck of land that anchors Cape Cod to mainland Massachusetts. The Canal is roughly 17.4 miles long, and connects Cape Cod Bay in the north to Buzzards Bay in the south. The 540-foot width of the canal is spanned by the Cape Cod Canal Railroad Bridge and two highway bridges, the Bourne and the Sagamore.
Cape Cod Canal
Traffic lights governing the approach of vessels over 65 feet are located at either end of the canal.
The usefulness of a canal for maritime transportation was apparent as early as the 17th century, when residents of the Plymouth colony scouted the low-lying stretch of land between the Manomet and the Scusset rivers; however, the first attempts at building an artificial waterway did not take place until the late 19th century. One failed attempt had already been made by the time August Belmont, Jr's "Boston, Cape Cod and New York Canal Company" succeeded in completing the first working Cape Cod Canal. Construction on the Canal began on June 22, 1909, with the canal opening on a limited basis in 1914, and completed in 1916. This privately owned toll canal had a maximum width of 100 feet (30 m), a minimum depth of 25 feet, and took a somewhat difficult route from Phinney Harbor at the top of Buzzards Bay. Due to the narrow channel and navigation difficulty, several accidents occurred which limited traffic and blackened the reputation of the Canal. As a result, toll revenues failed to meet investors' expectations.
During World War I, German U-boats attacked ships travelling along the far Atlantic coast of Cape Cod, making the Canal an important "safe" shipping lane. During the war, the Federal Railroad Administration took control of the Canal. When the war was over, the disappointed "Boston, Cape Cod and New York Canal Company", viewing the Canal as a bad investment, refused to take it back. In 1928, the government purchased the Canal, to be operated by the United States Army Corps of Engineers as a free public waterway.
From 1935-1940, the government rebuilt the canal, increasing its approach width to 540 feet and its depth to 32 feet. The southern entrance to the canal was rebuilt to proceed directly from Buzzards Bay, rather than through Phinney Harbor.
Issue #204 -
Tectonic plate
A tectonic plate is a piece of the Earth's crust (or lithosphere). The surface of the Earth consists of seven major tectonic plates and many more minor ones.
The plates are around 100 km (60 miles) thick and consist of two principal types of material: oceanic crust (also called sima) and continental crust (sial). Under both lies a relatively plastic layer of the Earth's mantle called the asthenosphere, which is in constant motion. This is in turn underlaid by a solid layer of mantle.
The tectonic plates of the world were mapped in the second half of the 20th century.
The composition of the two types of crust differs markedly. Oceanic crust consists largely of basaltic rocks, while the continental crust consists principally of lower density granitic rocks rich in aluminium and silica. The two types of crust also differ in thickness, with continental crusts considerably thicker than oceanic.
The churning of the asthenosphere carries the plates along in a process known as continental drift, which is explained by the theory of plate tectonics. Interaction between the plates creates mountains and volcanoes, as well as giving rise to earthquakes and other geological phenomena.
The boundaries of the plates do not coincide with those of the continents. For instance, the North American Plate covers not only North America but also Greenland, far eastern Siberia and northern Japan.
As far as is known, the Earth is the only planet in the Solar System to possess tectonic plates, although there have been suggestions that Mars may also have possessed plates in the past before the planet's crust froze in place.
Issue #205 -
Krafla
Krafla is a volcanic system with a diameter of about 20 km in the north of Iceland in the Mývatn region. Its highest peak reaches up to 818 m.
Krafla
Elevation: 2,133 ft (650 m)
Coordinates: 65°44'0" N 16°47'0" W
Location: Iceland
Type: Caldera
Last eruption: 1984
Part of Krafla is one of the two VÃti craters of Iceland. The second one is part of Askja. The Icelandic word "vÃti" means "hell". In former times, people often believed hell to be under volcanoes. The volcano Hekla was also held for hell during the Middle Ages. The crater VÃti near Krafla most recently erupted in 1976. In its center is a blue lake.
The Krafla area also includes Námafjall, a volcanic active area with hot springs.
During the years 1724-29 and in 1746, there were the so-called Mývatn fires. A lot of fissures opened up and the lava fountains could be seen even in the south of the island. A big lava flow destroyed parts of the village ReykjahlÃð, but most of the inhabitants survived having been in the church which lies on an elevation of terrain.
The last volcanic eruption at Krafla took place in the 1980s.
Since 1977 the geothermal energy is put to use by means of a small power station.
Lava flow during a rift eruption at Krafla volcano, northern Iceland, in 1984.
Issue #206 -
Strait of Gibraltar
The Strait of Gibraltar (Spanish: Estrecho de Gibraltar) is the strait which separates the Atlantic Ocean from the Mediterranean Sea. It is often called by a plural form: the Straits of Gibraltar, or a short form: Strog (STRait Of Gibraltar) as it is known in the Navy circles.
The Strait of Gibraltar as seen from space.
The name comes from the Arabic name of "Jebel Tariq" meaning Tariq's mountain. It refers to the Berber Muslim general Tariq ibn-Ziyad who conquered Spain in 711.
On the northern side is Spain and Gibraltar, on the southern side Morocco and Ceuta (a Spanish exclave in North Africa). Its boundaries were known to antiquity as the Pillars of Hercules. There are some small islands, like the disputed Isla Perejil, that is claimed by Spain and Morocco.
The Strait of Gibraltar has a very strategic location. Ships that travel from the Atlantic to the Mediterranean and vice versa, pass through this strait overlooked by the Rock of Gibraltar. Also, very many people who travel from Europe to Africa and vice versa, travel through this strait. During World War II, the British controlled the straits from their nearby base. German submarines entering the Mediterranean Sea were effectively trapped, because they couldn't leave on the surface and the undersea currents were too strong to leave underwater.
The depth is about 300 m, and it is about 14 km wide at its narrowest point.
For a number of years the Spanish and Moroccan governments have been jointly investigating the feasibility of a tunnel underneath the strait, similar to the Channel tunnel between England and France. A new three-year study for a railway tunnel was announced in 2003.
Also, a group of American and British engineers have studied the feasibility of building a bridge to span the straits. Such a bridge would be of a combination suspension-truss design and would dwarf any existing bridge in height (over 3,000 feet) and length (15 km). The 1979 science fiction novel The Fountains of Paradise by Arthur C. Clarke featured such a bridge.
The all-but-landlocked Mediterranean has an evaporation rate higher than the combined inflow of all the rivers that empty into it. The sill of the Strait of Gibraltar acts to limit mixing of water between the cold, less saline Atlantic and the warm Mediterranean waters, which are so much saltier that they sink below the constantly incoming Atlantic water and form a highly saline (thermohaline, both warm and salty) bottom water, called the Mediterranean Outflow; it flows out and down the continental slope, losing salinity, until it equilibrates after mixing at a depth of about 1000 m. The Mediterranean outflow water can be traced for thousands of kilometres before losing its identity.
Some 5 million years ago, the Strait closed, effectively turning the Mediterranean into a huge salty lake that eventually dried up, in what is known as the Messinian Salinity Crisis.
Issue #207 -
Cumberland Falls
Cumberland Falls, sometimes called the Little Niagara, the Niagara of the South, or the Great Falls, is a large waterfall on the Cumberland River in southeastern Kentucky. Spanning the river at the border of McCreary and Whitley counties, the waterfall is the central feature of Cumberland Falls State Resort Park, which itself is surrounded by the Daniel Boone National Forest.
Cumberland Falls by day. On clear moonlit nights, the mist from the falls occasionally produces a moonbow.
On average the falls, which flow over a resistant sandstone bed, are 68 feet (21 m) high and 125 feet (38 m) wide, with a water flow of 3,600 cubic feet per second (100 m³/s).
Under a full moon on clear nights, an elusive lunar rainbow or moonbow is sometimes formed by the mist emanating from the falls. The site is promoted as being one of only two in the world to feature this phenomenon, with Victoria Falls, at the border of Zambia and Zimbabwe, as the other. Actually, almost any waterfall can produce a moonbow under ideal conditions; however, many comparable sites have too much light for this feature to be visible.
History and preservation
Long known to Native Americans of the area, Cumberland Falls received its name from Zachary Green, whose party discovered it during an expedition in 1770. From the 1860s to the 1930s, Cumberland Falls and the surrounding land were privately held. The Moonbow Inn, a popular hotel dating to around 1875, was perched on a ledge overlooking the falls.
The area was a favorite vacation destination for T. Coleman DuPont, a Kentucky native and U.S. Senator from Delaware. Disturbed by plans to build a hydroelectric dam at the site, in 1930 DuPont purchased and donated 600 acres (2.4 km²) surrounding the falls to Kentucky, urging the commonwealth to set aside the property as a state park. Despite DuPont's death later that year, additional land was purchased, and in 1933 the state legislature designated the property as Kentucky's third state park. Much of the early work at the park, including construction of DuPont Lodge and cabins for guests, was undertaken during the Great Depression by Civilian Conservation Corps (CCC) and Works Progress Administration (WPA) employees.
With a reported 700,000 to 1 million visitors per year, the park remains one of Kentucky's busiest and most profitable state parks.
Issue #208 -
Kings Canyon
Kings Canyon is part of the Watarrka National Park in Northern Territory, Australia. Sitting at the western end of the George Gill Range, it is 323 km southwest of Alice Springs and 1,316 km south of Darwin.
Overview of Kings Canyon from the Rim Walk.
Description
The walls of Kings Canyon are over 100 metres high, with the Kings Creek at the bottom. Parts of the gorge is a sacred Aboriginal site and visitors are prohibited from walking off track.
Two walks exists at Kings Canyon. The 2 km (return) and approximately 1 hour Kings Creek Walk traces the bottom of the gorge. At the end of the walk is a platform, with views of the canyon walls above. The 6 km (loop) and 3-4 hour Kings Canyon Rim Walk traces the top of the canyon. A steep climb at the beginning of the walk takes the visitor up to the top, with spectacular views of the gorge below and of the surrounding landscape. About half way during the walk, a detour descends to Garden of Eden, a permanent waterhole surrounded by lush plant life. The last half of the walk passes through a large maze of weathered sandstone domes, reminscent of the Bungle Bungle. A slow descend brings the visitor back to the starting point (the loop can also be done in reverse, but the National Park sign posts at the carpark encourages the walk in one direction).
View from the Kings Canyon Gorge at sunset.
The 22 km Giles Track connects Kings Canyon to Kathleen Springs to the southwest (Kathleen Springs is also accessible from the paved road to Kings Canyon from Uluru/Yulara and Alice Springs.
Visitor's Information
As with many tracks in the central Australian desert, visitors are advised to avoid walking during the middle of the day when the temperature is the highest and the sun most direct. Sun-screen, a hat, plently of water (about 1 litre per hour at the hottest time), and a fly net are essential.
The Kings Canyon Resort operated by Voyages 6 km to the west offers camping, budget rooms, and standard hotel rooms.
View of the sandstone domes at Kings Canyon.
Issue #209 -
Tierra del Fuego
Tierra del Fuego (Spanish: Land of Fire) is an archipelago at the southernmost tip of South America. In 1881 it was divided between Argentina and Chile. The archipelago consists of a main island (Isla Grande de Tierra del Fuego, often called Tierra del Fuego as well), and a group of smaller islands. It is separated from the continent by the Strait of Magellan. The southern point of the archipelago, in Chile, forms Cape Horn.
A true-colour image of Tierra del Fuego captured by NASA's Terra satellite on March 28, 2003.
The main industries are oil, natural gas, sheep farming and ecotourism. The largest island is Tierra del Fuego, or Isla Grande, with an area of 48,100 km². Half of this island, and the islands west and south of it, are part of the Magallanes Region of Chile, the capital and chief town of which is Punta Arenas, situated on the mainland across the strait. The biggest Chilean towns are Porvenir, on the main island, and Puerto Williams, on Navarino Island. Puerto Toro lies a few kilometers south of Puerto Williams and is the southernmost town in the world.
Cities of Tierra del Fuego
The eastern part of the archipelago belongs to Argentina, being part of the Tierra del Fuego Province; its capital, Ushuaia, is the world's most southerly city, the other important town being Rio Grande, near the Atlantic coast.
Its name comes from Ferdinand Magellan, who was the first European to pass it in 1520, he (likely incorrectly) believed he was seeing the many fires (fuego in Spanish) of the Amerindians, which were visible from the sea. He believed that the "Indians" were waiting in the forests to ambush his armada. It is however, more likely that the fires he witnessed were from natural sources such as lightning.
Cerro Sombrero Village, Chile. It was founded to serve as a petroleum campsite.
Four native Fuegians, including "Jemmy Button" (Orundellico), were brought from Tierra del Fuego by Robert Fitzroy on the first voyage of the Beagle in 1830. They were taken to meet the King and Queen in London and were to an extent celebrities. The surviving three returned to Tierra del Fuego with the Beagle with Charles Darwin, who made extensive notes about his visit to the islands.
Issue #210 -
Cape Reinga
Cape Reinga (or Te Rerenga Wairua in the Maori language) is the northwesternmost tip of the Aupouri Peninsula, at the northern end of the North Island of New Zealand.
Cape Reinga
Cape Reinga is located over 100 km north of the nearest small town of Kaitaia. There is a road all the way but suitable vehicles can travel much of the way via Ninety Mile Beach and Te Paki stream bed.
Meeting of the seas
The cape separates the Tasman Sea from the Pacific Ocean. From the lighthouse it is possible to watch the tidal race, as the Tasman Sea meets the Pacific Ocean. This makes for unsettled waters just off the coast.
Cape Reinga Lighthouse
Cape Reinga is often mistaken as being the northernmost point of the North Island. North Cape's Surville Cliffs, 30 kilometres to the east of Cape Reinga, are slightly more northerly.
Maori mythology
According to Maori mythology, the spirits of the dead travel to Cape Reinga on their journey to the afterlife in the spiritual homeland of Hawaiki. At Cape Reinga they depart the mainland by leaping off the ancient pohutukawa tree on the cape. They turn briefly at the Three Kings Islands for one last look back towards the land, then continue on their journey. Reinga means the leaping-off place and Te Rerenga Wairua means the leaping-off place of spirits.
Lighthouse
The lighthouse at Cape Reinga was built in 1941 and first lit during May of that year.
The Cape Reinga lighthouse replaced a lighthouse located on nearby Motuopao Island, which had been built 1879. Accessing the lighthouse was difficult due to the rough seas in the area. In 1938, it was decided to move the lighthouse to Cape Reinga for safety reasons. The complete lantern fittings from Motuopao Island were reused at Cape Reinga.
Cape Reinga Lighthouse
The lighthouse was fitted with a 1,000 watt electrical lamp that could be seen for 26 nautical miles (48 km). The lamp was powered by a diesel generator.
In 1987, the lighthouse was fully automated and the lighthouse keepers were withdrawn. The lighthouse is now monitored remotely from Wellington. In May of 2000 the original lens and lamp were replaced by a 50 watt beacon. The beacon is powered by batteries that are recharged by solar cells. The beacon flashes every 12 seconds and can be seen for 19 nautical miles (35 km).
Issue #211 -
Johnson Street Bridge
The Johnson Street Bridge is a bascule bridge that spans the harbor of Victoria, British Columbia. It is nicknamed "Big Blue" because of its distinctive blue color.
The Johnson Street Bridge
It was designed by the Strauss Bascule Company and built by the City of Victoria Engineering Department. The bridge was completed in January 1924 at a cost of Can$918,000. The original wood deck was replaced by a steel grid in 1966 and the steel structure was repainted in 1979 as part of an extensive renovation.
The Johnson Street Bridge opening
The bridge has two separate structures, the railroad and the highway, that operate independently. The main span is 148 ft (45 m) in length and weighs 350 tons. The approaches are fixed girders, the east is 110 ft (34 m) and the west is 73 ft (22 m). The counterweights are made of hollow concrete and total 780 tons. Daily traffic is 30,000 vehicles.
Issue #212 -
Lake Huron
Lake Huron is one of the five Great Lakes of eastern North America and separates Michigan from Ontario. Georgian Bay, the easternmost part of Lake Huron, is entirely within Canada. Lake Huron's name comes from early French explorers who named it based on the Huron Indians inhabiting the region.
The Great Lakes from space; Lake Huron is the third from the left.
Lake Huron is separated from Lake Michigan, which lies at the same level, and connects by the narrow Straits of Mackinac, making them geologically and hydrologically the same body of water (sometimes called Lake Michigan-Huron). Lake Superior is slightly higher than both. It drains into the St. Marys River at Sault Ste. Marie which then flows southward into Lake Huron. The water then flows south to the St. Clair River, at Port Huron, Michigan and Sarnia, Ontario. Cities on Lake Huron include: Saginaw, Michigan, Bay City, Michigan, Alpena, Michigan, Cheboygan, Michigan, St. Ignace, Michigan, Port Huron, Michigan, and Sarnia, Ontario.
The Great Lakes Waterway continues thence to Lake St. Clair, the Detroit River and Detroit, Michigan, into Lake Erie and thence, via Lake Ontario and the St. Lawrence River, to the Atlantic Ocean.
Ipperwash Beach, Lake Huron.
The surface of Lake Huron is 579 feet (176 metres) above sea level. The lake's average depth is 195 feet (59 metres), while the maximum depth is 750 feet (230 metres). It covers an area of about 23,000 square miles (59 600 square kilometres). It contains 3,538 cubic km of water. The shoreline extends roughly 3,827 miles (6,159 kilometres). Like the other Great Lakes, it is the remnant of the larger Glacial Lake Agassiz, formed by melting ice as the continental glaciers retreated.
A notable feature of the lake is Manitoulin Island, the world's largest lake island.
Issue #213 -
Rio Grande
Known as the Rio Grande in the United States and as the RÃo Bravo (or, more formally, the RÃo Bravo del Norte) in Mexico, the river rises in the San Juan Mountains of Colorado, USA, flows through the San Luis Valley, then south into New Mexico through Albuquerque and Las Cruces to El Paso, Texas, on the U.S.–Mexico border.
The Rio Grande flowing in Big Bend National Park
The river has, since 1845, marked the boundary between Mexico and the United States from the twin cities of El Paso, Texas, and Ciudad Juárez, Chihuahua, to the Gulf of Mexico. As such, it was across this river that Texan slaves fled when seeking their freedom, aided by Mexico's liberal colonization policies and abolitionist stance.
The major international border crossings along the river are Ciudad Juárez and El Paso; Laredo, Texas, and Nuevo Laredo, Tamaulipas; McAllen-Hidalgo, Texas, and Reynosa, Tamaulipas; and Brownsville, Texas, and Matamoros, Tamaulipas. Other notable border towns are the Texas/Coahuila pairings of Del Rio–Ciudad Acuña and Eagle Pass–Piedras Negras.
Use of the water of the Rio Grande is regulated by the Rio Grande Compact, an interstate pact between Colorado, New Mexico and Texas; and a treaty between the United States and Mexico. The Rio Grande is over-appropriated, that is, there are more users for the water than there is water in the river. Since the summer of 2003, much of the river from southern New Mexico to the Big Bend National Park has been dry. Ecologists fear that unless rainfall returns to normal levels during the next few years and strict water conservation measures are adopted by communities along the river, the Rio Grande may soon become extinct.
The watershed of the Rio Grande
The Rio Grande rises in high mountains and flows for much of its length at high elevation; El Paso is 1,147 m (3,762 feet) above sea level. In New Mexico the river flows through the Rio Grande Rift from one sediment-filled basin to another, cutting canyons between the basins and supporting a fragile bosque ecosystem in its floodplain. From El Paso eastward the river flows through desert. Only in the sub-tropical lower Rio Grande Valley is there extensive irrigated agriculture. The river ends in a small sandy delta at the Gulf of Mexico. During periods of extended dry weather, the river will actually cease flowing into the Gulf.
Millions of years ago, the Rio Grande ended at the bottom of the Rio Grande Rift in Lake Cabeza de Vaca. But about 1 million years ago the stream was "captured" and began to flow east.
Issue #214
