Victoria Falls (реферат)

Язык: английский
Формат: реферат
Тип документа: Word Doc
0 1480
Скачать документ

Реферат на тему:

Victoria Falls

Victoria Falls with relatively low water in the dry season

HYPERLINK “http://en.wikipedia.org/wiki/Africa” \o “Africa” Africa ‘s
Victoria Falls or Mosi-oa-Tunya are, by some measures, the largest
HYPERLINK “http://en.wikipedia.org/wiki/Waterfall” \o “Waterfall”
waterfall on the planet, as well as being among the most unusual in
form, and having arguably the most diverse and easily-seen HYPERLINK
“http://en.wikipedia.org/wiki/Wildlife” \o “Wildlife” wildlife of any
major waterfall site.


Although being neither the highest nor widest waterfalls in the world,
the claim for being largest is based on a width of 1.7 km (1 mile) and a
height of 108 m (360 ft), forming what may be the largest sheet of
falling water in the world. No waterfalls are both wider and higher.
Their maximum flow rate compares well with other major waterfalls (see
table below). HYPERLINK “http://en.wikipedia.org/wiki/” \l “_note-WW”
\o “” [1]

The unusual form of Victoria Falls enables virtually the whole width of
the falls to be viewed face-on, at the same level as the top, from a
distance as close as 60 m (200 ft), because the whole HYPERLINK
“http://en.wikipedia.org/wiki/Zambezi_River” \o “Zambezi River” Zambezi
River drops into a deep, narrow slot-like HYPERLINK
“http://en.wikipedia.org/wiki/Chasm” \o “Chasm” chasm , connected to a
long series of HYPERLINK “http://en.wikipedia.org/wiki/Gorges” \o
“Gorges” gorges . Few other waterfalls allow such a close approach on
foot to the heart of their power. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Google” \o “” [2]

Many of Africa’s animals and birds can be seen in the immediate vicinity
of Victoria Falls, and the continent’s range of river fish are well
represented in the Zambezi, enabling wildlife viewing and sports fishing
to be combined with sightseeing. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “” [3]

Victoria Falls are one of HYPERLINK
“http://en.wikipedia.org/wiki/Africa” \o “Africa” Africa ‘s major
tourist attractions, and a HYPERLINK
“http://en.wikipedia.org/wiki/UNESCO” \o “UNESCO” UNESCO HYPERLINK
“http://en.wikipedia.org/wiki/World_Heritage_Site” \o “World Heritage
Site” World Heritage Site (see box below). They are shared between
HYPERLINK “http://en.wikipedia.org/wiki/Zambia” \o “Zambia” Zambia and
HYPERLINK “http://en.wikipedia.org/wiki/Zimbabwe” \o “Zimbabwe”
Zimbabwe , and each country has a national park to protect them and a
town serving as a tourism centre: HYPERLINK
“http://en.wikipedia.org/wiki/Mosi-oa-Tunya_National_Park” \o
“Mosi-oa-Tunya National Park” Mosi-oa-Tunya National Park and
HYPERLINK “http://en.wikipedia.org/wiki/Livingstone%2C_Zambia” \o
“Livingstone, Zambia” Livingstone in Zambia, and HYPERLINK
“http://en.wikipedia.org/wiki/Victoria_Falls_National_Park” \o “Victoria
Falls National Park” Victoria Falls National Park and the town of
HYPERLINK “http://en.wikipedia.org/wiki/Victoria_Falls%2C_Zimbabwe” \o
“Victoria Falls, Zimbabwe” Victoria Falls in Zimbabwe. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-UNEP” \o “” [4]

Physical features

For a considerable distance above the falls, the Zambezi flows over a
level sheet of HYPERLINK “http://en.wikipedia.org/wiki/Basalt” \o
“Basalt” basalt , in a shallow HYPERLINK
“http://en.wikipedia.org/wiki/Valley” \o “Valley” valley bounded by
low and distant HYPERLINK “http://en.wikipedia.org/wiki/Sandstone” \o
“Sandstone” sandstone hills. The river’s course is dotted with
numerous tree-clad HYPERLINK “http://en.wikipedia.org/wiki/Island” \o
“Island” islands , which increase in number as the river approaches the
falls. There are no mountains, HYPERLINK
“http://en.wikipedia.org/wiki/Escarpments” \o “Escarpments” escarpments
, or deep valleys which might create a waterfall, only flat HYPERLINK
“http://en.wikipedia.org/wiki/Plateau” \o “Plateau” plateau extending
hundreds of kilometres in all directions. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Google” \o “” [2] HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “” [3]

The falls are formed as the full width of the river plummets in a single
vertical drop into a chasm 60–120 m (200–400 ft) wide, carved by its
waters along a fracture zone in the basalt plateau. The depth of the
chasm, called the First Gorge, varies from 80 m (262 ft) at its western
end to 108 m (360 ft) in the centre. The only outlet to the First Gorge
is a 110 m (360 ft) wide gap about two-thirds of the way across the
width of the falls from the western end, through which the whole volume
of the river pours into the Victoria Falls HYPERLINK
“http://en.wikipedia.org/wiki/Gorges” \o “Gorges” gorges . HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Google” \o “” [2] HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “” [3]

There are two islands on the crest of the falls large enough to divide
the curtain of water even at full flood: Boaruka Island (or Cataract
Island) near the western bank, and Livingstone Island, near the middle.
At less than full flood, islets divide the curtain of water into
separate parallel streams. The main ones are named, going from Zimbabwe
(west) to Zambia (east): Leaping Water (called Devil’s Cataract by
some), Main Falls, Rainbow Falls (the highest) and the Eastern Cataract.
HYPERLINK “http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “”

Flood and dry season flow rates

The Zambezi basin above the falls experiences a HYPERLINK
“http://en.wikipedia.org/wiki/Rainy_season” \o “Rainy season” rainy
season from late November to early April, and a HYPERLINK
“http://en.wikipedia.org/wiki/Dry_season” \o “Dry season” dry season
the rest of the year. The river’s annual HYPERLINK
“http://en.wikipedia.org/wiki/Flood” \o “Flood” flood season is
February to May with a peak in April, HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-WCD” \o “” [5] and this is
when the falls is the most impressive in terms of power and its
thunderous rumbling sound. The spray from the falls rises typically to a
height of over 400 metres (1300 ft), and sometimes even twice as high,
and is visible from up to 50 km (30 miles) away. At full moon, a
“moonbow” can be seen in the spray instead of the usual daylight
rainbow. During the flood season however it is impossible to see the
foot of the falls and most of its face, and the walks along the cliff
opposite it are in a constant shower and shrouded in mist. Close to the
edge of the cliff, spray shoots upwards like reversed rain, especially
at Zambia’s Knife-Edge Bridge. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “” [3]

As the dry season takes effect, the islets on the crest become wider and
more numerous and in September to January up to half of the rocky face
of the falls may become dry, and the bottom of the First Gorge can be
seen along most of its length. At this time it becomes possible, though
not necessarily safe, to walk across some stretches of the river at the
crest. It is also possible to walk to the bottom of the First Gorge at
the Zimbabwean side. The minimum flow which occurs in November is around
a tenth of the April figure, a larger variation than for other major
falls, which brings Victoria Falls’ annual average flow rate well down.
HYPERLINK “http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “” [3]

The best time to see Victoria Falls depends on what you want to see. May
to August offers the best compromise between a flow rate which impresses
with its power, and the falls not being obscured by spray.

The Victoria Falls are roughly twice the height of North America’s
HYPERLINK “http://en.wikipedia.org/wiki/Niagara_Falls” \o “Niagara
Falls” Niagara Falls and well over twice the width of its horseshoe
falls. In height and width Victoria Falls is only rivalled by South
America’s HYPERLINK “http://en.wikipedia.org/wiki/Iguazu_Falls” \o
“Iguazu Falls” Iguazu Falls which is divided into over 270 smaller
falls and cataracts. See table for comparisons.

The Victoria Falls Gorges

Satellite image showing the broad Zambezi falling into the narrow cleft
and subsequent series of zigzagging gorges (top of picture is north)

The whole volume of the river pours through the First Gorge’s 110 m (360
ft) wide exit for a distance of about 150 m (500 ft), then enters a
zigzagging series of gorges named in order from the first. Water
entering the Second Gorge makes a sharp right turn and has carved out a
deep pool called the Boiling Pot. Reached via a steep footpath from the
Zambian side, it is about 150 m (500 ft) across, its surface is smooth
at low water, but at high water is marked by slow, enormous swirls and
heavy boiling turbulence. HYPERLINK “http://en.wikipedia.org/wiki/” \l
“_note-Spectrum” \o “” [3] Objects which are swept over the falls are
frequently found swirling about here or washed up at the north-east end
of the Second Gorge, such as the occasional dead hippo, or more
tragically, people. This is where the bodies of Mrs Moss and Mr Orchard,
mutilated by crocodiles, were found in 1910 after two canoes were
capsized by a hippo at Long Island above the falls. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-NRJ4” \o “” [6]

The principal gorges are (see reference for note about these
measurements): HYPERLINK “http://en.wikipedia.org/wiki/” \l “_note-0”
\o “” [7] HYPERLINK “http://en.wikipedia.org/wiki/” \l “_note-1” \o
“” [8]

First Gorge: the one the river falls into now

Second Gorge: (spanned by the Victoria Falls Bridge), 250 m south of
falls, 2.15 km long (270 yd south, 2350 yd long)

Third Gorge: 600 m south, 1.95 km long (650 yd south, 2100 yd long)

Fourth Gorge: 1.15 km south, 2.25 km long (1256 yd south, 2460 yd long)

Fifth Gorge: 2.55 km south, 3.2 km long (1.5 mi south, 2 mi long)

Songwe Gorge: 5.3 km south, 3.3 km long, (3.3 mi south, 2 mi long) named
after the small Songwe River coming from the north-east, and the deepest
at 140 m (460 ft), at the end of the dry season.

“http://en.wikipedia.org/w/index.php?title=Batoka_Gorge&action=edit” \o
“Batoka Gorge” Batoka Gorge : below the Songwe, the gorge is called the
Batoka Gorge (which is also used as an umbrella name for all the
gorges). It is about 120 km (75 mi) long (the straight line distance to
its end is about 80 km (50 mi) east of the falls) and takes the river
through the HYPERLINK “http://en.wikipedia.org/wiki/Basalt” \o
“Basalt” basalt HYPERLINK “http://en.wikipedia.org/wiki/Plateau” \o
“Plateau” plateau to the valley in which HYPERLINK
“http://en.wikipedia.org/wiki/Lake_Kariba” \o “Lake Kariba” Lake Kariba
now lies.

The walls of the gorges are close to vertical and generally about 120 m
(400 ft) high, but the level of the river in them varies by up to 20
metres (65 ft) between wet and dry seasons. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “” [3]

How the Victoria Falls formed

“Leaping Waters”, the westernmost cataract of Victoria Falls and the
start of a line of weakness where the next falls will form.

The recent geological history of Victoria Falls can be seen in the form
of the gorges below the falls. The basalt plateau over which the Upper
Zambezi flows has many large cracks filled with weaker sandstone. In the
area of the current falls the largest cracks run roughly east to west
(some run nearly north-east to south-west), with smaller north-south
cracks connecting them.

Over at least 100,000 years, the falls have been receding upstream
through the Batoka Gorges, eroding the sandstone-filled cracks to form
the gorges. The river’s course in the current vicinity of the falls is
north to south, so it opens up the large east-west cracks across its
full width, then it cuts back through a short north-south crack to the
next east-west one. The river has fallen in different eras into
different chasms which now form a series of sharply zig-zagging gorges
downstream from the falls. HYPERLINK “http://en.wikipedia.org/wiki/” \l
“_note-Spectrum” \o “” [3]

Ignoring some dry sections, the Second to Fifth and the Songwe Gorges
each represents a past site of the falls at a time when they fell into
one long straight chasm as they do now. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “” [3] Their
sizes indicate that we are not living in the age of the widest ever

The falls has already started cutting back the next major gorge, at the
dip in one side of the ‘Leaping Waters’ section of the falls. This is
not actually a north-south crack, but a large east-north-east line of
weakness across the river, and that is where the next full width falls
will eventually form.

Further geological history of the course of the HYPERLINK
“http://en.wikipedia.org/wiki/Zambezi_River” \o “Zambezi River” Zambezi
River is in the article of that name.

Precolonial History

Archaeological sites around the falls have yielded Homo habilis stone
artefacts from 3 million years ago, 50,000-year-old Middle Stone Age
tools and Late Stone Age (10,000 and 2,000 years ago) weapons,
adornments and digging tools. HYPERLINK “http://en.wikipedia.org/wiki/”
\l “_note-UNEP” \o “” [4] Iron-using HYPERLINK
“http://en.wikipedia.org/wiki/Khoisan” \o “Khoisan” Khoisan
HYPERLINK “http://en.wikipedia.org/wiki/Hunter-gatherer” \o
“Hunter-gatherer” hunter-gatherers (bushmen) displaced these Stone Age
people and in turn were displaced by HYPERLINK
“http://en.wikipedia.org/wiki/Bantu” \o “Bantu” Bantu tribes such as
the southern Tonga people known as the HYPERLINK
“http://en.wikipedia.org/wiki/Tokaleya” \o “Tokaleya” Batoka/Tokaleya ,
who called the falls Shungu na mutitima. The HYPERLINK
“http://en.wikipedia.org/wiki/Matabele” \o “Matabele” Matabele , later
arrivals, named them aManza Thunqayo, and the HYPERLINK
“http://en.wikipedia.org/wiki/Makololo” \o “Makololo” Makololo (whose
language is used by the HYPERLINK
“http://en.wikipedia.org/wiki/Lozi_people” \o “Lozi people” Lozi people
) called them Mosi-oa-Tunya. All these names mean essentially the same
thing, ‘the smoke that thunders’. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-NRJ” \o “” [9]

The first European to see the falls was HYPERLINK
“http://en.wikipedia.org/wiki/David_Livingstone” \o “David Livingstone”
David Livingstone on HYPERLINK
“http://en.wikipedia.org/wiki/November_17” \o “November 17” 17 November
HYPERLINK “http://en.wikipedia.org/wiki/1855” \o “1855” 1855 ,
during his 1852-1856 journey from the upper Zambezi to the mouth of the
river. The falls were well known to the HYPERLINK
“http://en.wikipedia.org/wiki/Batswana” \o “Batswana” Batswana ,
HYPERLINK “http://en.wikipedia.org/wiki/Matabele” \o “Matabele”
Matabele and HYPERLINK “http://en.wikipedia.org/wiki/Balozi” \o
“Balozi” Balozi , but Europeans were sceptical of their reports,
perhaps thinking that the lack of mountains and valleys on the plateau
made a falls unlikely. The Arabs may have known of them under a name
equivalent to ‘the end of the world’. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-2” \o “” [10]

Livingstone had been told about the falls before he reached them from
upriver and was paddled across to a small island that now bears the name
Livingstone Island. Livingstone had previously been impressed by the
HYPERLINK “http://en.wikipedia.org/wiki/Ngonye_Falls” \o “Ngonye Falls”
Ngonye Falls further upstream, but found the new falls much more
impressive, and named them after HYPERLINK
“http://en.wikipedia.org/wiki/Victoria_of_the_United_Kingdom” \o
“Victoria of the United Kingdom” Queen Victoria . He wrote of the falls
“No one can imagine the beauty of the view from anything witnessed in
England. It had never been seen before by European eyes; but scenes so
lovely must have been gazed upon by angels in their flight”. HYPERLINK
“http://en.wikipedia.org/wiki/” \l “_note-Spectrum” \o “” [3]

In 1860, Livingstone returned to the area and made a detailed study of
the falls with HYPERLINK
“http://en.wikipedia.org/wiki/John_Kirk_%28explorer%29” \o “John Kirk
(explorer)” John Kirk . Other early European visitors included
HYPERLINK “http://en.wikipedia.org/wiki/Portugal” \o “Portugal”
Portuguese explorer HYPERLINK
“http://en.wikipedia.org/wiki/Serpa_Pinto” \o “Serpa Pinto” Serpa Pinto
, HYPERLINK “http://en.wikipedia.org/wiki/Czech_Republic” \o “Czech
Republic” Czech explorer HYPERLINK
“http://en.wikipedia.org/wiki/Emil_Holub” \o “Emil Holub” Emil Holub ,
who made the first detailed plan of the falls and its surroundings in
1875 (published in 1880), HYPERLINK “http://en.wikipedia.org/wiki/” \l
“_note-3” \o “” [11] and British artist HYPERLINK
“http://en.wikipedia.org/wiki/Thomas_Baines” \o “Thomas Baines” Thomas
Baines , who executed some of the earliest paintings of the falls. Until
the area was opened up by the building of the railway in 1905, though,
the falls were seldom visited by other Europeans.

Нашли опечатку? Выделите и нажмите CTRL+Enter

Похожие документы

Оставить комментарий

Уведомление о
Заказать реферат!
UkrReferat.com. Всі права захищені. 2000-2019