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Colca Canyon

Colca Canyon is the canyon of the Colca River in southern Peru. It is located about 100 miles (160 kilometers) northwest of Arequipa.

Long thought to be the deepest canyon on earth at 10,725 ft (3,269 m), it is more than twice as deep as the Grand Canyon in the United States. The Cotahuasi Canyon nearby to the northwest is now known to be deeper at 11,488 ft (3,501 m), and the Yarlung Tsangpo Canyon along the Brahmaputra in Tibet is now thought to be the deepest canyon in the world at 16,650 ft (5,075 m). Since they are such major features of the landscape, the Colca and Cotahuasi canyons are both easily recognizable in even low-resolution satellite photos of the region.

Colca Canyon

The Colca River starts high in the Andes at Condorama Crucero Alto and changes its name to Majes, and then to Camana before reaching the Pacific Ocean. Parts of the canyon are habitable, and Inca and pre-Inca terraces are still cultivated along the less precipitous canyon walls. The small town of Chivay is on the upper Colca River, where the canyon is not so deep but where many terraces are present in the canyon and continue for many kilometers downstream. As the canyon deepens downriver, a series of small villages is spread out over the approximately 35 mi (56 km) between Chivay and the village of Cabanaconde. The canyon reaches its greatest depth nearby, and in contrast, only about 15 mi (24 km) to the southeast rises the 20,630-ft (6,288-m) Nevado Ampato, a snow-capped extinct volcano.

The canyon is the habitat of the great Andean condor (Vultur gryphus), a species that has seen world-wide effort to preserve it.

The Spanish laid out towns along the canyon and built churches there, but the towns did not thrive and have faded out of memory. In the 1980s, the Majes Hydroelectric Project built roads and opened the area to outsiders. Access today is usually through Arequipa.

Cruz del Condor is a popular tourist stop to view the condors, which hunt in the early morning and late afternoon. At this point the canyon floor is 3,960 ft (1,200 m) below the rim of the canyon.

Issue #393

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Miramar Peninsula

The Miramar Peninsula is at the southeastern end of the city of Wellington, New Zealand. It contains the suburbs of Miramar, Seatoun, and Strathmore. The isthmus connecting the peninsula to the rest of Wellington separates Evans Bay to the north from Lyall Bay to the south, and is the location of Wellington International Airport.

Miramar Peninsula

To the east of the peninsula lies the mouth of Wellington Harbour, which opens into Cook Strait at its southern end. The notorious rocks of Barrett Reef lie close to the shore of the peninsula.

The peninsula was originally called Watt's Peninsula. In 1872 the first settler in the area, James Coutts Crawford, changed the name to Miramar which means Behold the sea or Wonderful Sea.

The original Maori name was Whataitai.

Miramar Borough was formed on November 18, 1904.

Film director Peter Jackson has built a multi-million dollar series of studios, sound stages, pre- and post-production facilities in Miramar.

Issue #394

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Kimberlite

Kimberlite is an ultrapotassic, ultramafic, igneous rock composed of olivine, phlogopite, pyroxene and garnet, with a variety of chemically anomalous trace minerals.

Hewn kimberlite core sample from the James Bay Lowlands region of Northern Ontario, Canada. Green olivine grains and purplish red garnet are visible. The sample is 13 cm (5 inches) long.

Morphology and volcanology

Kimberlites are found as dikes and volcanic pipes which underlie and are the source for rare and relatively small explosive volcanoes (maars). Kimberlites in the Guyana Shield, in Venezuela and French Guyana, form thin, tabular dipping sills.

Kimberlite pipes are the result of explosive diatreme volcanism from very deep mantle derived sources. These volcanic explosions produce vertical columns of rock that rise from deep magma reservoirs. The morphology of kimberlite pipes are varied but generally include a sheeted dyke complex of tabular, vertically dipping feeder dykes in the root of the pipe which extend down to the mantle. Within 1.5-2 km of the surface the highly pressured magma explodes upwards and expands to form a conical to cylindrical diatreme, which erupts to surface. The surface expression is rarely preserved but is usually similar to a maar volcano.

Petrology

Kimberlites are divided into Group I (basaltic) and Group II (micaceous) kimberlites. This division is made along mineralogical grounds.

The general consensus reached on kimberlites is that they are formed deep within the mantle, at between 150 and 450 kilometres depth, from anomalously enriched exotic mantle compositions, and are erupted rapidly and violently, often with considerable CO2 and volatile components. It is this depth of melting and generation which makes kimberlites prone to hosting diamond xenocrysts.

The mineralogy of Group I kimberlites is considered to represent the products of melting of lherzolite and harzburgite, eclogite and peridotite under lower mantle conditions. The mineralogy of Group II kimberlites may represent a similar melting environment to that of Group I kimberlites, the difference in mineralogy being caused by the preponderance of water versus Ócarbon dioxide.

Group I kimberlites

Group I kimberlites are of CO2-rich ultramafic potassic igneous rocks dominated by a primary mineral assemblage of forsteritic olivine, magnesian ilmenite, chromian pyrope, almandine-pyrope, chromian diopside (in some cases subcalcic), phlogopite, enstatite and of Ti-poor chromite. Group I kimberlites exhibit a distinctive inequigranular texture cause by macrocrystic (0.5-10 mm) to megacrystic (10-200 mm) phenocrysts of olivine, pyrope, chromian diopside, magnesian ilmenite and phlogopite in a fine to medium grained groundmass.

The groundmass mineralogy, which more closely resembles a true composition of the igneous rock, contains forsteritic olivine, pyrope garnet, Cr-diopside, magnesian ilmenite and spinel.

Group II kimberlites

Group-II kimberlites (or orangeites) are ultrapotassic, peralkaline rocks rich in volatiles (dominantly H2O). The distinctive characteristic of orangeites is phlogopite macrocrysts and microphenocrysts, together with groundmass micas that vary in composition from phlogopite to "tetraferriphlogopite" (anomalously Fe-rich phlogopite). Resorbed olivine macrocrysts and euhedral primary crystals of groundmass olivine are common but not essential constituents.

Characteristic primary phases in the groundmass include: zoned pyroxenes (cores of diopside rimmed by Ti-aegirine); spinel-group minerals (magnesian chromite to titaniferous magnetite); Sr- and REE-rich perovskite; Sr-rich apatite; REE-rich phosphates (monazite, daqingshanite); potassian barian hollandite group minerals; Nb-bearing rutile and Mn-bearing ilmenite.

Kimberlitic indicator minerals

Kimberlites are peculiar igneous rocks because they contain a variety of mineral species with peculiar chemical compositions. These minerals such as potassic richterite, chromian diopside (a pyroxene), chromium spinels, magnesian ilmenite and high-aluminium garnets are generally absent from most other igneous rocks, making them particularly useful as indicators for kimberlites.

These indicator minerals are generally sought in stream sediments in modern alluvial material. Their presence, when found, may be indicative of the presence of a kimberlite within the erosional watershed which has produced the alluvium.

Economic importance

Kimberlites are the most important source of primary diamonds. Many kimberlite pipes also produce rich alluvial or eluvial diamond placer deposits.

The deposits occurring at Kimberley, South Africa were the first recognized and the source of the name. The Kimberley diamonds were originally found in weathered kimberlite which was colored yellow by limonite, and so was called yellow ground. Deeper workings encountered less altered rock, serpentinized kimberlite, which miners call blue ground.

Issue #395

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Balboa Island, Newport Beach, California

Balboa Island is an area of Newport Beach, California actually comprising three modified or artificial islands in Newport Harbor: Balboa Island, the largest; the smaller Little Balboa Island to the east of Balboa Island, joined by a two-lane bridge; and the smallest Collins Island to the northwest of Balboa Island, joined by a one-lane bridge. The Balboa Island community is joined to the mainland by a short two-lane bridge on the northeast of Balboa Island, and a privately-operated fleet of three, three-car ferryboats (Balboa Island Ferry) which provide access across the harbor to the Balboa Peninsula which lies to the south.

Balboa Island

Balboa Island is one of the most expensive real estate markets in North America outside of Lower Manhattan. A two-bedroom house with a water view from the living room can cost about $3 million.

Local tradition has it that Balboa Island is where the frozen chocolate banana was first marketed: There are snack shops on Marine Avenue that will dip a frozen banana on a stick into chocolate sauce and roll it around in ground nuts or candy sprinkles. This legend is referenced in the American television show Arrested Development in which the wealthy Bluth family of Orange County owns a frozen chocolate banana stand on Balboa Island. Also popular is the Balboa bar, a square of vanilla ice cream on a stick prepared in a similar fashion.

The zip code for Balboa Island is 92662.

The island was not always easily accessible. Newport Harbor was still largely undredged, and sailboat was often the only way to get around. Robert McFadden, an early Balboa Harbor developer had established a successful fishing wharf on the Balboa Peninsula and by 1906, the Pacific Electric line Red Cars began service to the Balboa Peninsula and Balboa Pavilion, and soon, the Red Cars would bring thousands of summertime visitors from Los Angeles.

Within a few years, real estate promoters began sending salesmen up to wealthy Pasadena and soon to Los Angeles (both connected by the Red Cars) to promote property in and around Newport Harbor. Considerable Balboa Island property was sold in Pasadena, and this is one of the reasons that so many longtime Island residents continue to have family and contacts in the Pasadena area. One of these real estate promoters was William Collins. At the time, Balboa Island was little more than a sandbar that was usually swallowed up by high tide.

In 1908 and 1909, with permission of the Orange County Board of Supervisors, Collins dredged the surrounding bay and piled the sand on the little sandbar that he came to call Balboa Island. Collins originally sold lots on the Island for as little as $25, with the promise of a bridge and ferry service to follow. Joseph Allan Beek, while still a student at Pasadena City College, was enchanted with the area, and became one of Collins' salesmen. Joe Beek played a crucial role in the development of Balboa Island, and spent a lifetime devoted to it. He later served as Secretary of the California State Senate until his death in 1968.

The island grew slowly at first, but in 1916, it became part of the City of Newport Beach. By 1921, homes were beginning to fill in the Island and Balboa Peninsula. Roads to the Newport Harbor area were still largely undeveloped, and many people still arrived by rail to the peninsula and took the ferry over to the island. Although the first bridge from the mainland to the North Bayfront was built in 1912, it was not capable of carrying automobiles until 1929, when it was refurbished.

In 1919, after complaints of inadequate service, the city of Newport Beach awarded a fifteen-year franchise to Joseph Beek to run the ferry. At first it only carried pedestrians, but by 1921, was also transporting cars to the Island. The ferry operation remains in the Beek family.

In 1953, the International Boy Scout Jamboree held its event where Newport Center and Fashion Island now sit. Thousands of tents were pitched in the area reachable only by a two-lane muddy trail called Palisades Road. The road was soon paved, and later the name was changed to Jamboree Road in honor of the Scouts.

Today it remains a major thoroughfare through Newport Beach, and ends at Balboa Island. Over the years, Balboa Island has developed into a close-knit community, home to professionals, families, retirees, students and celebrities.

Issue #396

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Pacific temperate rain forests

The Pacific temperate rain forests of Canada and the United States are the largest temperate rain forest zone on the planet. The Pacific temperate rain forests occur on west-facing coastal mountains along the Pacific coast of North America, from Kodiak Island in Alaska to northern California, and are part of the Nearctic ecozone.

Pacific temperate rain forests often grow right up to the shoreline.

These rain forests occur in a number of ecoregions, which vary in their species composition, but all are predominantly conifers, sometimes with an understory of broadleaf trees and shrubs. The Pacific temperate rain forests can be found along the west coast from Alaska south to California. The forests in the north contain predominantly Sitka spruce and western hemlock, while those in the coastal forests are home as well to Coast Redwood (Sequoia sempervirens), Coast Douglas-fir (Pseudotsuga menziesii). Notably, the three tallest species of trees are found here.

The Pacific temperate rainforests are characterized by a high amount of rainfall, in some areas as much as 100 inches per year. Dense growths of epiphytes and mosses cover the trees, and lush vegetation is present everywhere.

Issue #397

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Geysir

Geysir (sometimes known as The Great Geysir), in the Haukadalur valley, Iceland, is the oldest known geyser and one of the world's most impressive examples of the phenomenon. The English word geyser to describe a spouting hot spring derives from Geysir (which itself is derived from the Icelandic verb gjósa meaning to erupt. The English verb gush is probably related to that word). Geysir lies on the slopes of Laugarfjall hill which is also the home to Strokkur geyser.

Eruptions at Geysir can hurl boiling water up to 60 metres in the air. However, eruptions may be infrequent, and have in the past stopped altogether for years at a time. Currently, eruptions are occurring about three times a day on average.

Strokkur, a geyser in the Geysir area

History

The oldest accounts of a geyser at Haukadalur date back to 1294. Earthquakes in the area caused significant changes in local neighbouring landscape creating several new hot springs. Changes in the activity of the Geysir and the surrounding geysers are strongly related to earthquake activity. In records dated 1630 the geysers erupted so violently that the valley around them trembled.

In recent times earthquakes have tended to revive the activity of Geysir which then subsides again in the following years. Before 1896 Geysir was almost dormant before an earthquake that year caused eruptions to begin again, occurring several times a day, lasting up to an hour and causing spouts of up to 60 metres in height. By 1935 the geyser was almost dormant again and a manmade channel was dug through the silica rim around the edge of the geyser vent. This ditch caused a lowering of the watertable and a revival in activity. Gradually this channel too clogged with silica and eruptions again became rare. In 1981 the ditch was cleared again and eruptions could be stimulated, on special occasions, by the addition of soap. Following environmental concerns the practice of adding soap was seldom employed during the 1990s. During that time Geysir seldom erupted. When it did erupt, it was spectacular, sending boiling water about forty metres into the air. On the Icelandic National Day authorized government geologists would force an eruption. A further earthquake in 2000 revived the geyser again. Initially eruptions were taking place on average eight times a day. By July 2003 this activity had again decreased to around three times per day.

The nearby geyser Strokkur erupts much more frequently than Geysir, erupting to heights of up to 20 metres every five minutes or so. Strokkur's activity has also been affected by earthquakes, although to a lesser extent than the Great Geysir. There are around thirty much smaller geysers and hot pools in the area, including one called Litli Geysir ('Little Geysir').

Descriptions of the Great Geysir and Strokkur have been given in every travel guide to Iceland published from the 18th century onwards. Today the geyser remains an essential element of almost every tourist's itinerary. The place is, together with Þingvellir and the Gullfoss waterfall, part of the most famous sights of Iceland, the Golden Circle.

Ownership of the Geysir area

Until 1894 the Geysir area was owned by a local farmer. In that year the area was sold to James Craig (later Lord Craigavon), a whisky distiller and future Prime Minister of Northern Ireland. Initially he erected large fences around the site and an entrance fee was charged for visitors wishing to view the geysers. The following year however Craig appeared to tire of his project and gave the area as a present to a friend, E. Craig, who dropped the entrance fees. Later Craig's nephew Hugh Rogers inherited the site. In 1935 he sold the site to film director Sigurður Jónasson who subsequently donated it to the Icelandic people in perpetuity.

Issue #398

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Shenandoah Valley

The Shenandoah Valley region of western Virginia, from Winchester to Staunton, is bounded by the Blue Ridge mountains to the East and the Allegheny mountains to the West. Harrisonburg, Waynesboro,Winchester and Front Royal are also among the many small towns in the Valley. The region also includes the eastern panhandle of West Virginia and the cities of Martinsburg and Harpers Ferry. Down the center of the Shenandoah Valley runs the Massanutten Mountain range, encompassing Powell's Fort Valley in Shenandoah County.

A farm in the fertile Shenandoah Valley

The word Shenandoah was derived for the Native American expression for "Beautiful Daughter of the Stars." The Valley Pike (or Valley Turnpike) began as a migratory trail for tribes such as the Delaware and Catawba and became the major thoroughfare of wagons, and in time, motor vehicles. By the 20th century, the Valley Turnpike was a toll road, eventually being acquired by the Commonwealth of Virginia and becoming U.S. Highway 11. For much of the length, the newer Interstate 81 parallels the old Valley Pike.

Geologically the Shenandoah Valley reaches as far as Roanoke; however, it and Lexington are not in the Shenandoah River basin, which reaches somewhat south of Staunton. From north to south, the Shenandoah Valley encompasses two counties in West Virginia: Berkeley County and Jefferson County; and seven counties in Virginia: Frederick County, Clarke County, Warren County, Shenandoah County, Page County, Rockingham County, and Augusta County.

The Shenandoah Valley is a productive agricultural region. Despite the great promise of the rich farmland of the Valley, the Blue Ridge Mountains, crossed by Governor Alexander Spotswood's legendary Knights of the Golden Horseshoe Expedition at Swift Run Gap in 1716, were a major obstacle to colonial expansion from the east. Instead, the Valley was first settled by German and then by Scotch-Irish immigrants from Pennsylvania in the 1730s. The former were known as "Shenandoah Deitsch". Both stocks came south into the Valley from the Potomac River, in contrast to the largely English settlement of the Virginia tidewater and piedmont regions.

The Shenandoah Valley was a major site of battles in the American Civil War.

Issue #399

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Celtic Sea

The Celtic Sea (Irish: An Mhuir Cheilteach) is the area of the Atlantic Ocean off the south coast of Ireland. It is bounded to the east by Saint George's Channel, the Bristol Channel and the English Channel, as well as adjacent portions of Wales, Cornwall and Brittany. The Celtic heritage of the bounding lands give the sea its name, first proposed by E.W.L. Holt in 1921. The northern portion of this sea had previously been considered part of Saint George's Channel and the southern part had no common name; the need for a common name came to be felt because of common geology and hydrology. The name is now commonly used by workers in the oil and fishing industries.

Map of the Celtic Sea, an arm of the Atlantic.

The southern and western boundaries are less clearly defined. Holt suggested the 200 fathom (366 m) marine contour and Ushant; the International Hydrographic Organization definition uses plumb lines and extends slightly further south.

Issue #400

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