Sahara: The Great Desert

Desert is a dry, hot, and full of sand and dusty place burning under the scorching sun yet it is a miracle of Mother Nature. Desertification has become a worldwide problem today but some deserts are naturally occurring and full of surprise. As the world's biggest desert, the Sahara covers a third of the African continent-an area about the size of the United States. It is one of the hottest places on Earth. Even though temperatures there may rise to 136 F (57.7 C), its dryness, not heat makes a place like the Sahara a desert. It is bounded in the east by the Red Sea and it stretches west to the Atlantic Ocean. To the north, the Sahara Desert's northern boundary is the Mediterranean Sea, while in the south it ends at the Sahel, an area where the desert landscape transforms into a semi-arid tropical savanna.  The Sahara covers large parts of Algeria, Chad, Egypt, Libya, Mali, Mauritania,Morocco, Niger, Western Sahara, Sudan and Tunisia. It is one of three distinct physiographic provinces of the African massive physiographic division. 

The desert landforms of the Sahara are shaped by wind or by occasional rains and include sand dunes and dune fields or sand seas, stone plateaus, gravel plains, dry valleys, and salt flats. Unusual landforms include the Richat Structure in Mauritania. Several deeply dissected mountains and mountain ranges, many volcanic, rise from the desert, including the Aïr Mountains, Ahaggar Mountains, Saharan Atlas, Tibesti Mountains, Adrar des Iforas, and the Red Sea hills. The highest peak in the Sahara is Emi Koussi, a shield volcano in the Tibesti range of northern Chad. Most of the rivers and streams in the Sahara are seasonal or intermittent, the chief exception being the Nile River, which crosses the desert from its origins in central Africa to empty into the Mediterranean. Underground aquifers sometimes reach the surface, forming oases, including the Bahariya, Ghardaïa, Timimoun, Kufrah, and Siwah. The central part of the Sahara is hyper-arid, with little vegetation. The northern and southern reaches of the desert, along with the highlands, have areas of sparse grassland and desert shrub, with trees and taller shrubs in wadis where moisture collects.

To the north, the Sahara reaches to the Mediterranean Sea in Egypt and portions of Libya, but in Cyrenaica and the Magreb, the Sahara borders Mediterranean forest, woodland, and scrub ecoregions of northern Africa, which have a Mediterranean climate characterized by a winter rainy season. According to the botanical criteria of Frank White and geographer Robert Capot-Rey, the northern limit of the Sahara corresponds to the northern limit of Date Palm cultivation and the southern limit of Esparto, a grass typical of the Mediterranean climate portion of the Maghreb and Iberia. The northern limit also corresponds to the 100 mm (3.9 in) isohyet of annual precipitation. To the south, the Sahara is a belt of dry tropical savanna with a summer rainy season that extends across Africa from east to west. The southern limit of the Sahara is indicated botanically by the southern limit of Cornulaca monacantha or northern limit of Cenchrus biflorus, a grass typical of the Sahel.  According to climatic criteria, the southern limit of the Sahara corresponds to the 150 mm (5.9 in) isohyet of annual precipitation. 

Read More

Pagan Pagodas in Myanmar

Pagan or also known as Bagan is located 425 miles north of Yangon, Myanmar. It is a famous religious city consists of many pagodas, stupas and shrines built around 11-13 AD. Pagan was the capital city of northern Burma for more than thousands of years.  It's believed that more than 13,000 structures once occupied the Pagan plain. Pagan is a religious and archaeological marvel, and some would say it's "a wonder of the ancient World." The temples stretch for eight miles along the bank of the Ayeyarwady River and for about two miles inland. At some points the ruins are so dense that it's often described as a place where it's impossible to move without touching something sacred. 

People of the Burman ethnic group had been already converted to Indian religion like Mahayana. Under King Anawrahta (reigned 1044-77), the ethnic Burmans finally conquered the other people of the region, including people called the Mon, who were previously dominant in the south. They sent the Mon royal family making it the capital and centre of an official, fundamentalist form of Hinayana (Theravada) Buddhism adopted from Ceylon (Sri Lanka), about 1056. This initiated the period of Pagan’s greatness, which was sustained at first by Mon artistic traditions. Many numbers of large and exquisite monasteries and shrine were built and maintained during the next 200 years and it was made possible both by the great wealth of the royal exchequer and by the large number of slaves, skilled and unskilled, whose working lives were dedicated to the support of each institution. The city became one of the most important centres of Buddhist learning.

Lesser buildings are grouped around the more important pagodas and temples. Scattered around these are smaller pagodas and buildings, some of which may once have been aristocratic palaces and pavilions later adapted to monastic uses--e.g., as libraries and preaching halls. All are based on Indian prototypes, modified during subsequent development by the Mon. The principal architectural theme is the Buddhist stupa, a tall bell dome, designed originally to contain near its apex the sacred relics of Buddhist saints. Another is the high, terraced plinth, which may be supplemented by stairs, gateways, extra stupas, and pinnacles and symbolizes a sacred mountain.

Read More

Niagara Falls

 Enchantingly magnificent in sight, Niagara Falls can be categorized as the most beautiful and powerful waterfall in the world. Located on the Niagara River in North America, it is 17 miles (27 km) north-northwest of Buffalo, New York and 75 miles (121 km) south-southeast of Toronto, between the twin cities of Niagara Falls, Ontario, and Niagara Falls, New York. The falls is composed of two parts separated by Goat Island: the Horseshoe Falls on the Canadian side and the American Falls on the American side. The smaller Bridal Veil Falls are also located on the American side, separated from the main falls by Luna Island. The international boundary line was originally drawn through Horseshoe Falls in 1819, but the boundary has long been in dispute due to natural erosion and construction.

Niagara Falls were formed when glaciers receded at the end of the Wisconsin glaciation (the last ice age), and water from the newly formed Great Lakes carved a path through the Niagara Escarpment en route to the Atlantic Ocean. While not exceptionally high, the Niagara Falls is very wide. More than 6 million cubic feet (168,000 m3) of waterfalls over the crest line every minute in high flow, and almost 4 million cubic feet (110,000 m3) on average. When the ice melted, the upper Great Lakes emptied into the Niagara River, which followed the rearranged topography across the Niagara Escarpment. In time, the river cut a gorge through the north facing cliff, or cuesta. Because of the interactions of three major rock formations, the rocky bed did not erode evenly. The top rock formation was composed of erosion resistant limestone and Lockport dolostone. That hard layer of stone eroded more slowly than the underlying materials. The aerial photo on the right clearly shows the hard caprock, the Lockport Formation (Middle Silurian), which underlies the rapids above the falls, and approximately the upper third of the high gorge wall.

Immediately below the hard-rock formation, comprising about two thirds of the cliff, laid the weaker, softer, sloping Rochester Formation (Lower Silurian). This formation was composed mainly of shale, though it has some thin limestone layers. It also contains ancient fossils. In time, the river eroded the soft layer that supported the hard layers, undercutting the hard cap rock, which gave way in great chunks. This process repeated countless times, eventually carving out the falls. Submerged in the river in the lower valley, hidden from view, is the Queenston Formation (Upper Ordovician), which is composed of shales and fine sandstones. All three formations were laid down in an ancient sea, their differences of character deriving from changing conditions within that sea.

Read More

Mount Everest

Mount Everest is the highest mountain in the world. Situated as the highest peak out of many in the Himalayas mountain range in Nepal, it extends to the sky as high as 29 002feet (8,848m) or so. Shifting tectonic plates continue to push Everest upward, along with the whole Himalaya mountain range, at 1.6 to 3.9 inches (4 to 10 centimeters) per year. In 1841, Sir George Everest, Surveyor General of India from 1830 to 1843, first recorded the location of Everest. It was subsequently named "Peak XV". In 1865, it was renamed Mt. Everest to honor Sir George. Everest is also called Chomolungma in Tibet and Sagarmatha in Nepal.

The summit of Everest is the point at which the Earth's surface reaches the greatest distance above sea level. Several other mountains are sometimes claimed as alternative "tallest mountains on Earth". Mauna Kea in Hawaii is tallest when measured from its base; it rises over 10,200 m (6.3 mi) when measured from its base on the mid-ocean floor, but only attains 4,205 m (13,796 ft) above sea level. By the same measure of base to summit, Mount McKinley, in Alaska, is also taller than Everest. Despite its height above sea level of only 6,193.6 m (20,320 ft), Mount McKinley sits atop a sloping plain with elevations from 300 m (980 ft) to 900 m (3,000 ft), yielding a height above base in the range of 5,300 to 5,900 m (17,400 to 19,400 ft); a commonly quoted figure is 5,600 m (18,400 ft). By comparison, reasonable base elevations for Everest range from 4,200 m (13,800 ft) on the south side to 5,200 m (17,100 ft) on the Tibetan Plateau, yielding a height above base in the range of 3,650 to 4,650 m (11,980 to 15,260 ft). The summit of Chimborazo in Ecuador is 2,168 m (7,113 ft) farther from the Earth's centre (6,384.4 km (3,967.1 mi)) than that of Everest (6,382.3 km (3,965.8 mi)), because the Earth bulges at the Equator. However, Chimborazo attains a height of only 6,267 m (20,561 ft) above sea level, and by this criterion it is not even the highest peak of the Andes.

Read More

Great Barrier Reef

For almost 2000km long, Great Barrier Reef is the world’s largest coral reef eco system in the world. It is roughly parallel to the coast of Queensland, Australia and composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometres (1,600 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi). The Great Barrier Reef has long been known to and used by the Aboriginal Australian and Torres Strait Islander people, and is an important part of local groups' cultures and spirituality. The reef is a very popular destination for tourists, especially in the Whitsunday Islands and Cairns regions. Tourism is an important economic activity for the region, generating $1 billion per year. 

The Great Barrier Reef includes the smaller Murray Islands. It reaches from Torres Strait in the north to the unnamed passage between Lady Elliot Island (its southernmost island) and Fraser Island in the south. Lady Elliot Island is located 1,915 km (1,190 mi) southeast of Bramble Cay as the crow flies.

From 20,000 years ago until 6,000 years ago, sea level rose steadily. As it rose, the corals could then grow higher on the hills of the coastal plain. By around 13,000 years ago the sea level was only 60 metres (200 ft) lower than the present day, and corals began to grow around the hills of the coastal plain, which were, by then, continental islands. As the sea level rose further still, most of the continental islands were submerged. The corals could then overgrow the hills, to form the present cays and reefs. Sea level here has not risen significantly in the last 6,000 years. It is estimated that the age of the present, living reef structure at 6–8,000 years old.  The Great Barrier Reef World Heritage Area has been divided into 70 bioregions, of which 30 are reef bioregions. In the northern part of the Great Barrier Reef, ribbon reefs and deltaic reefs have formed; these structures are not found in the rest of the reef system. There are no atolls in the system, and reefs attached to the mainland are rare. Lagoonal reefs are found in the southern Great Barrier Reef, and further north, off the coast of Princess Charlotte Bay. Cresentic reefs are the most common shape of reef in the middle of the system, for example the reefs surrounding Lizard Island. Cresentic reefs are also found in the far north of the Great Barrier Reef Marine Park, and in the Swain Reefs (20–22 degrees south). Reefs are found in the northern and southern parts, near Cape York Peninsula, Princess Charlotte Bay, and Cairns. Most of the islands on the reef are found on planar reefs. 

 Great Barrier Reef is home for large variety of marine life including many vulnerable or endangered species, some of which may be endemic to the reef system. Thirty species of whales, dolphins, and porpoises have been recorded in the Great Barrier Reef, including the dwarf minke whale, Indo-Pacific humpback dolphin, and the humpback whale. Large populations of dugongs live there. Six species of sea turtles come to the reef to breed – the green sea turtle, leatherback sea turtle, hawksbill turtle, loggerhead sea turtle, flatback turtle, and the olive ridley. The green sea turtles on the Great Barrier Reef have two genetically distinct populations, one in the northern part of the reef and the other in the southern part. Fifteen species of sea grass in beds attract the dugongs and turtles, and provide fish habitat. The most common genera of sea grasses are Halophila and Halodule.

Read More