A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the structural integrity of such a chamber, greatly diminishing its capacity to support its own roof, and any substrate or rock resting above. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface. Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur over the course of a century, the formation of a caldera is a rare event, occurring only a few times within a given window of 100 years. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018.
This is a list of the lists of islands in the world grouped by country, by continent, by body of water, and by other classifications. For rank-order lists, see the other lists of islands below.
Twin cities are a special case of two neighboring cities or urban centres that grow into a single conurbation – or narrowly separated urban areas – over time. There are no formal criteria, but twin cities are generally comparable in status and size, though not necessarily equal; a city and a substantially smaller suburb would not typically qualify, even if they were once separate. Tri-cities and quad cities are similar phenomena involving three or four municipalities.
A natural arch, natural bridge, or rock arch is a natural landform where an arch has formed with an opening underneath. Natural arches commonly form where inland cliffs, coastal cliffs, fins or stacks are subject to erosion from the sea, rivers or weathering.
In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually composed of rock that is resistant to weathering and erosion. The sedimentary rocks that are most likely to form cliffs include sandstone, limestone, chalk, and dolomite. Igneous rocks such as granite and basalt also often form cliffs.
Eighth Wonder of the World is an unofficial title sometimes given to new buildings, structures, projects, designs or even people that are deemed to be comparable to the seven Wonders of the World.
The Window of the World is a theme park located in the western part of the city of Shenzhen in the People's Republic of China. It has about 130 reproductions of some of the most famous tourist attractions in the world squeezed into 48 hectares. The 108 metre (354 ft) tall Eiffel Tower dominates the skyline and the sight of the Pyramids and the Taj Mahal all in proximity to each other are all part of the appeal of this theme park.
Elk Falls Provincial Park is a provincial park in British Columbia, Canada. It is 1,807 hectares in size and is located at the east end of John Hart Lake on the northwest side of the city of Campbell River, on Vancouver Island.
Tarutao National Park consists of 51 islands in the Strait of Malacca, off the coast of Satun Province of southern Thailand. The Tarutao National Park consists of two island groups: Tarutao and Adang-Rawi, which are scattered from 20 to 70 kilometres' distance from the south-westernmost point of mainland Thailand. The park covers an area of 931,250 rai ~ 1,490 square kilometres (580 sq mi) of which 1,260 square kilometres (490 sq mi) ocean and 230 square kilometres (89 sq mi) island. The southernmost end of the park lies on the border with Malaysia, just north of Langkawi. Tarutao became Thailand's second marine national park on 19 April 1974. The coastal Khao Sam Roi Yot National Park had been designated in 1966.
Where the Hell is Matt? is an Internet phenomenon that features a video of Dancing Matt doing a dance "jig" in many different places around the world in 2005. The video garnered popularity on the video sharing site YouTube. There are now five major videos plus two outtakes and several background videos on YouTube. Matt dances alone in the first videos. In 2008 others join with him doing the dance "jig"; in 2010 he does the Diski Dance in South Africa. In 2012 he works with other dancers, sometimes using a local dance or another dance step.
Salt Creek Falls is a cascade and plunge waterfall on Salt Creek, a tributary of the Middle Fork Willamette River, that plunges into a gaping canyon in the Willamette National Forest near Willamette Pass in Lane County, Oregon. The waterfall is notable for its main drop of 286 feet (87 m), ranking third highest among plunge waterfalls in Oregon, after Multnomah Falls and Watson Falls.) The pool at the bottom of Salt Creek Falls waterfall is 66 feet (20 m) deep.
