Christchurch City (population 320,000) sits at the base of the long arc of
Pegasus Bay, bounded to the north by the Waimakariri River and to the
south by the old crater complex of the Port Hills and Banks Peninsula.
The heavily braided rivers of the South Island of New Zealand bring
greywacke rock from the Southern Alps to the west, forming the huge
alluvial pan (750,000 ha) of the Canterbury Plains. Braided rivers are
rare worldwide, found elsewhere only in Alaska, Canada, and the Himalayas.
They form a network of ever-changing channels weaving between temporary
shingle islands. In some places, the gravel they have transported from the
mountains formed by the clash of the Indo-Australian and Pacific Plates is
as much as 500 meters deep.
Banks Peninsula, named for explorer Captain Cook’s botanist, consists of
two overlapping extinct volcanoes, the Lyttelton Volcano and the Akaroa
Volcano. Since the last eruptive activity some six million years ago, the
volcanoes have been heavily eroded, dropping them from a peak of 1,500
meters down to around 500 meters.
During his quick 1770 visit, Cook mistook the peninsula for an island, but
the build up of the Canterbury Plains has seen it joined to the mainland
for at least 200,000 years.
Breaches in the crater walls have produced two long harbors: Lyttelton to
the north and Akaroa to the south. The former is the port for
Christchurch, and European settlers in the 1860s were quick to bore a
tunnel through to Christchurch rather than tackle the steep hills and long
swampy walk into the early settlement. The original idea was to settle at
the end of Lyttelton Harbour, but the huge mudflats exposed at low tide
put paid to that plan.
The shallow green waters of Lake Ellesmere (Waihora) to the south of the
city offer a refuge for wildlife. The estuary for the small Avon and
Heathcote rivers, just to the north of Lyttelton Harbour, is home to
godwits, curlews and other visitors from Siberia and Alaska, as Asian and
American birds reach the southernmost point of their annual migrations
This image was acquired by the Enhanced Thematic Mapper plus (ETM+) sensor flying aboard the Landsat 7 satellite on September 25, 2001.
New Zealand’s capital, Wellington, sits at the southwestern tip of North Island near the Cook Strait. The city in the second largest in New Zealand (after Auckland), and at 41 south latitude, it is the southernmost capital city in the world. The North and South Islands of New Zealand are located along the active Australian-Pacific tectonic plate boundary. The glancing collision of these two tectonic plates results in uplift of the land surface, expressed as low hills on North Island and the Southern Alps on South Island.
Colors ranging from deep brown to stark white give New Zealand’s South Island its intense beauty. The snow-capped Southern Alps run down the northern shore of the island. The mountains are rising as the Pacific Plate, the section of the Earth’s crust that holds the Pacific Ocean, including parts of New Zealand’s South Island, sinks beneath the Australia Plate, which holds the rest of New Zealand.
The crew of Expedition 13 recently passed a major milestone: as of late August 2006, more than one quarter of a million images of Earth had been taken from the International Space Station. The 250,000th image is an oblique view (a photograph taken from a side angle) of the city of Christchurch, New Zealand. This view provides a sense of perspective and accents topography, in contrast to nadir (directly downwards) views. Snow highlights the peaks of the Banks Peninsula to the southeast of the city. The peninsula has a radically different landscape compared to the adjoining, flat Canterbury Plains, where Christchurch (gray patch to the north) is located. The Banks Peninsula is formed from the overlapping cones of the extinct Lyttelton and Akaroa volcanoes. Subsequent erosion of the cones formed the heavily dissected terrain visible in the image, and sea level rise led to the creation of several harbors around the Peninsula. Erosion continues unabated today, as evidenced by the apron of greenish blue, sediment-laden waters surrounding the Banks Peninsula.