Ausralia is a vast continent embedded in the Indo-Australian tectonic plate that is moving northward against the Indonesian Islands. Most of its citizens live near the coast. This map names the states of Australia and shows its major road network:
All of Australia is pictured in this Landsat mosaic (a larger and somewhat different version appears near the bottom of page 7-3).
Most of Australia is semi-desert. Mountains are infrequent and relatively low. The geology of the continent is summarized in this simplified general map:
This map is similar but breaks down the structural and stratigraphic units more specifically:
We saw part of northwestern Australia when we examined the Pilbara district on page 2-6. We will look again here we will look more closely at one of the images making up that mosaic. This is the so-called Pilbara district of northwest Australia, near the coast, made up of Archean and Proterozoic rocks. Near the batholiths are Proterozic rocks making up the Hamersley Group. Some of the units are banded ironstones. This ASTER image shows off this spectacular geology:
This ground photo is typical of the country comprising the Pilbara district
In the Northern Territories is Arnhem Land, populated mostly by aborigines. This scene is about 200 km east of Darwin, the only large town in the region. The scene below was taken during a dry period, but rain forests (dark red) occur, and vegetation blooms after rains. This land contains animals such as portrayed in the movie "Crocodile Dundee".
Much of the Australian Interior is dry, harsh, inhospitable, and sparsely developed. This next scene lies in the Sturt Desert where New South Wales, South Australia, and Queensland meet. Numerous sand dunes aligned with long dimension running NW-SE blanket the landscape. Normally rainfall is less than 12 inches (30 cm) a year. But in this scene there had been a heavy period of rain a bit earlier such that water has collected (temporarily) in the low areas between dunes.
Approximately 80% of Australia is arid lands (the other 20% includes tropical forests in the north and temperate forests along some of the coasts). Only a fraction of the drier terrains have numerous sand dunes like those in the Sturt Desert above. Here are two views of the Great Sandy Desert in northwest Australia, the first showing some broad sandy cover, the second showing mostly bedrock with sparse vegetation:
A group of low plateaus appear in desert lands in interior Queensland. In this unusual satellite image of the Porcupine Gorge region, the individual plateaus stand out because of an interbedded basalt lava flow unit which traces their outlines as though with a dark pen:
The influence of a prolific, if short-lived, rainy season in the interior is evidenced in these next two Landsat scenes within the Great Artesian Basin, located at the border of Queensland and New South Wales. Top image: After especially heavy rains, the Barcoo River fills a depression with water that extends as a large lake, Lake Cuddapan. The surrounding land is also now displaying grass and marshy vegetation, the former suitable for cattle grazing. Bottom image: After the wet season, the land reverts to a barren state but the lake beds remain wet enough to support extensive wetlands vegetation.
Because so much of Australia is relatively flat lowlands, floods such as the one shown above spread over wide areas. This happened in January of 2009 in northern Australia when the Flinders River - normally a stream that flows over a semi-desert landscape - received copious water from heavy 'southern summer' rains and spilled over wide areas, as seen in the lower MODIS (on Aqua) image below:
The dry climate and lack of vegetation in much of Australia's interior favor excellent exposure and expression of geologic structures. Mountains in the Flinders Range are strikingly exposed in this ASTER image:
The main destination of tourists exploring the Australian Outback (interior) is the town of Alice Springs. Nearby is the MacDonnell Range, fold mountains that are expressed as ridges. In this next image, the Gosses Bluff impact crater (Section 18) is a small circular area to the north (near top center) of the Ranges.
Several hundred kilometers from Alice Springs is the country's most famous natural landmark known both by its aboriginal name, Uluru, and by the name given it by English settlers, Ayers Rock. This is the largest monolith in the world, being 3.8 km long and 348 meters high. It consists of arkose (feldspar-rich sandstone), in highly tilted strata. Now a National Park, it boasts several five star hotels within sight to accommodate the hundreds of thousands of visitors now trekking to it each year. Below we show two high resolution color images of Ayers Rock taken by the IKONOS satellite and an aerial oblique view in natural color.
The dissected plateau country in southeast Australia receives much more rainfall so that the region is heavily forested with eucalyptus, gum, mahogany, and ironwood, as well as tree ferns, palms, and other tropical vegetation near the coast. The Blue Mountains and the Hunter Range make up part of the scene below. The largest city (more than 4 million) in Australia, Sydney, lies between Botany Bay (south) and Port Jackson Bay (north) and extends inland at least 20 km (12 miles). This is how it appears in an Terra MISR image taken just before the Olympics 2000 began in September. The city itself is just right of center.
This Landsat image shows greater Sydney:
Zooming in closer on Sydney, look at this IKONOS image of part of that great city:
The downtown section of Sydney is impressive in this panoramic photograph:
Sydney's most famous landmark is the fabulous Opera House:
This marvelous structure, completed in 1972, shows up as a dominating feature in this Quickbird image of the harbor and downtown buildings of Sydney:
The 2000 Olympic Village in Sydney (outside the edge of the EO-1 image) is sharply singled out by an IKONOS-2 image:
Canberra, Australia's capital, is a newly built complex that has wide open spaces and initially a small population. Everything is built around a central lake:
By the mid '90s this Landsat TM subscene shows major population growth and spread, as the city itself also by then had many planted trees in full growth.
The only big city along the southwest coast of Western Australia is Perth on the Indian Ocean, shown here in a Landsat subscene. Flat plains inland from Perth end abruptly against a spread of low mountains, the Darling Range, heavily forested. The linear nature of the contact of plains with these uplands (part of the Paleozoic crystalline shield), suggest a fault.
We look next at an area about 725 km (450 miles) east of Perth and 160 km (100 miles) inland from the south coast. It is underlain by ancient Archean crystalline and sedimentary rocks that have been worn down to lowlands (plains). Natural vegetation is known locally as mallee scrub, a mixture of saltbush and bluebush. Most of the upper right has been undeveloped but over the years, much of the remaining area has been cleared by burning. Calcium-rich soils there, plus a rainfall of 25-38 cm (10-15 inches) per year, have favored development of numerous interlocking large farms. Wheat is the principal crop. Here in October (Australia�s spring), the fields show only the first stages of growth. Between the farmlands and the pristine terrain to the northeast is one of Australia�s electrified "rabbit-proof" fences designed to keep that marauding pest away from the croplands. Salt lakes appear in the virgin lands.
When tourists come to Australia, besides Ayer's Rock and Alice Springs, and of course Sydney, the third popular destination is the famed Great Barrier Reef off the coast of Queensland, as seen in this image:
A closer look from space shows parts of the reef complex just north of the city of Cairns - the prime spot for vacationers who wish to explore the reef.
One way is by air; here is an aerial view of the reef:
The best way is to explore parts of the Great Barrier Reef close up, either by sailing over it in a glass-bottomed boat or by snorkeling. This is an indication of what you would see:
The GBR, like much of the world's coral reefs elsewhere, is experiencing damage by bleaching (the white coral stalk in the above photo is an example), brought on both by warmer temperatures and by chemicals added to the seas by man. In this global warming era, there is a real danger that the coral reefs across the globe can by killed.
One of the most beautiful and scenic countries in the world is New Zealand, a pair of islands some 1600 km (1000 miles) southeast of Sydney. These landmasses form near a major plate boundary between the Pacific and Indo-Australian plates. New Zealand consists of two large islands, seen here in this satellite image:
North Island is notable for its several active volcanoes and a major geyser-hot steam field. This Envisat image shows most of North Island in more detail.
The capital of New Zealand is Auckland:
Auckland has grown into a modern city with an impressive skyline:
The second city in population is Wellington. Here it is as seen in an astronaut photo:
But to those who have toured N.Z., South Island is ranked as even more striking because of its spectacular mountains and lush plains. The snow-capped Southern Alps, a chain of complexly folded and metamorphosed rocks elevated by plate collision to current heights above 3000 meters (10000 ft). Their western side is bounded by the great Alpine fault, analogous to the San Andreas of California (and many visitors compare the landscapes of N.Z. to parts of that state). The entire South Island has been emvisaged in a Day-IR HCMM image (see page 9-8), shown next, in which many of the black patches are snow. Note the effect on the regional topography by the Alpine Fault (linear boundary below top center). On its south are high mountains; to the north are low plains.
On December 7, 2007 the MODIS instrument on Aqua obtained this cloud-free image of the South Island:
The Alps have been extensively glaciated, producing the rugged peaks and valleys walls that resemble Yosemite in California. As evident in the scene below, the eastern Alps give way to the Canterbury Plains, across which flow (top to bottom) the Waiau, Waimakariri, and Raikaia Rivers. The Banks Peninsula to the east is built up, in part, of several now extinct volcanoes. The city of Christchurch (blackish area) lies at its northwest end. Land use is mainly sheep and cattle husbandry, and wheat, oats, and fodder farming on the Plains.
This next photo is a bit of a trick. Christchurch is seen in the foreground but the Alps appear to be close-by. They are actually distant, but a telephoto lens was used to obtain this scene.
Movie-goers, and especially fans of the Lord of the Rings trilogy, should recognize this scenery. The entire Ring was filmed mostly in South Island of New Zealand, but with some scenes in North Island. The actors and crew were based out of South Island's largest town - Christchurch, seen here in an International Space Station photo (the 250000th picture taken from that platform). The circular hills are a dissected old volcanic edifice.
The kinship in appearance of the New Zealand Alps to those in Europe is evident in this Landsat 7 ETM+ image that shows Mt. Cook, at 3754 m (12316 ft) the highest point in this mountain chain, and almost twice as high as the highest mountain in nearby Australia. The ranges on the two islands were once connected before New Zealand split off.
The ground photo below was taken from the coast north of Christchurch looking at the terraces in the Canterbury Plains cut by the Karangama River with the high Alps in the background.
A closer look at the Southern Alps is afforded by these two images, the second being of Mt. Cook, highest in the range, and similar to the Matterhorn in the European Alps:
As one moves out into the great Pacific Basin beyond Australia and New Zealand, many island groups are found scattered about, mainly in low latitudes. Some of the islands shown below on this page are located on this map of Oceania - a general name given to many of the Pacific Ocean islands:
Tahiti is typical of Oceania's islands. It is volcanic in natureIt is located in the Society Islands of French Polynesia. Here it is from space, with the airport at Papeete shown as a thin red strip in the upper left of the island's shore:
Papeete is its largest city. The neighboring island of Moorea rises abruptly from the ocean, as it is the site of a large volcano.
Indeed, many Pacific islands are volcanic (see the Hawaiian Islands as the lead example, on page page 17-3). Some of those have fringes of coral around them. In this latter category, the third largest island is New Caledonia. This photo, taken by an astronaut aboard the ISS, shows a part of the island with its peninsula that contains the largest city, Noumea.
Many Pacific islands are atolls (see page 17-4 for other examples). These may be just fringing reefs with a lagoon inside, as exemplified by the Arno atoll in the Marshall Islands.
Some atolls are inhabited but the residents need to be supplied with food and necessities by ship since nearly all atolls are not self-sustaining. Atafu atoll (entrusted to New Zealand) is one such example; it has trees (note the coral (lighter blue) in its lagooon:
A typical atoll without a lagoon is Mantangi Island in the Fiji Island group of several hundred. The entire island is a coral reef some 3 km (2 miles) in length. It is fringed with submerged coral (lighter blue) and a white coral sand beach; inland the island is covered with tropical trees and brush.
Some atoll islands are well populated, as shown by Tongatapu in the Tonga Islands, a group near New Zealand.
This next image is the atoll of Tetiaroa, in the Society Islands. (These are part of French Polynesia and include Tahiti and Bora Bora. Its claim to fame is that it was purchased outright from the French government by Marlon Brando, the famed Hollywood actor:
Coral atolls can develop in clusters, as shown in this IKONOS image of the Maldives:
Other atolls are aligned in chains, as are the Tuomotu islands in French Polynesia. This archipelago contains 73 individual atolls, the largest of which is Rangiroa, whose top is 80 meters (250 ft) above sealevel. The islands are inhabited, despite the appearance of having little land mass.
The United States possesses a widespread collection of atolls and volcanic islands scattered about the Pacific. Here are two that are well known (Guam sends delegates to the Republican and Democratic conventions); check the captions for identities:
By now you should have formed the impression that the U.S. has many islands in its possession, both in North America and worldwide. Here is a List of American Islands produced by Wikipedia.
Islands are widespread over the Pacific. Some have notably histories in World War II. Midway northwest of the Hawaiian Islands was part of the turning point battle of the Japanese campaign. While it was being attached by Japanese carrier planes, U.S. carriers launched strikes at the Japanese, sinking four of their carriers. Here is Midway, still a U.S. Marine base; it is a very narrow coral reef:
General Douglas MacArthur, along with Admiral Chester Nimitz, made up the duo who devised the "island hopping" strategy that recaptured some islands that the Japanese had occupied earlier in their 1942 spread across the west Pacific. Guadalcanal and Tarawa were the sites of two of the most vicious battles. Tarawa appears here in this satellite image - one wonders why such a tiny island was so vital in the campaign but again the airport was the main motivation.
Several thousand miles east of the Tonga Islands is Easter Island, seen here from space. It is owned by Ecuador. Its claim to fame are the remarkable statues that awed the first explorers after its discovery.
With these last scenes, we conclude our odyssey around the fascinating landscapes and urban centers on our planet Earth.