Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption. Types of volcanic cones include stratocones, spatter cones, tuff cones, and cinder cones.
Scoria is a highly vesicular, dark-colored volcanic rock that may or may not contain crystals (phenocrysts). It is typically dark in color, and basaltic or andesitic in composition. Scoria is relatively low in density as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity greater than 1, and sinks in water. The holes or vesicles form when gases that were dissolved in the magma come out of solution as it erupts, creating bubbles in the molten rock, some of which are frozen in place as the rock cools and solidifies. Scoria may form as part of a lava flow, typically near its surface, or as fragmental ejecta, for instance in Strombolian eruptions that form steep-sided scoria cones. Chemical analysis of scoria found in Yemen showed that it was mainly composed of volcanic glass with a few zeolites. Most scoria is composed of glassy fragments and may contain phenocrysts. The word scoria comes from the Greek σκωρία, skōria, rust. A colloquial term for scoria is cinder.
The Auckland volcanic field is an area of monogenetic volcanoes covered by much of the metropolitan area of Auckland, New Zealand's largest city, located in the North Island. The approximately 53 volcanoes in the field have produced a diverse array of maars, tuff rings, scoria cones, and lava flows. With the exception of Rangitoto, no volcano has erupted more than once, but eruptions lasted for various periods ranging from a few weeks to several years. Rangitoto erupted twice; the first eruption occurred about 600 years ago, followed by a second eruption approximately 50 years later. The field is fuelled entirely by basaltic magma, unlike the explosive subduction-driven volcanism in the central North Island, such as at Mount Ruapehu and Lake Taupō. The field is currently dormant, but could become active again.
Tower Hill is an inactive volcano on the south-west coast of Victoria, Australia, approximately 275 kilometres (171 mi) west of Melbourne, and 15 kilometres (9 mi) north-west of Warrnambool. The Tower Hill crater is roughly 3 kilometres (2 mi) wide and 80 metres (260 ft) high, with a gradient of between 10% to 80% at the higher points. Within the crater, a series of later volcanic explosions formed a number of scoria cones and spheres, surrounded by a crater lake. Being a giant nested maar, Tower Hill is of international geological significance. The Dhauwurdwurrung name for the volcano is Koroitj.
The Auckland Domain is a large park in Auckland, New Zealand. It is the oldest park in the city, and at 75 hectares is one of the largest. Located in the central suburb of Grafton, the park contains all of the explosion crater and most of the surrounding tuff ring of the Pukekawa volcano.
The Panmure Basin, also sometimes known as the Panmure Lagoon, is a tidal estuary within a volcanic crater or maar in New Zealand's Auckland volcanic field, which erupted approximately 25,200 years ago. It is located to the south of Panmure town centre.
A cinder cone is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or cinder that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is symmetrical; with slopes between 30 and 40°; and a nearly circular ground plan. Most cinder cones have a bowl-shaped crater at the summit.
The Mount Edziza volcanic complex is a large and potentially active north-south trending complex volcano in Stikine Country, northwestern British Columbia, Canada, located 38 kilometres (24 mi) southeast of the small community of Telegraph Creek. It occupies the southeastern portion of the Tahltan Highland, an upland area of plateau and lower mountain ranges, lying east of the Boundary Ranges and south of the Inklin River, which is the east fork of the Taku River. As a volcanic complex, it consists of many types of volcanoes, including shield volcanoes, calderas, lava domes, stratovolcanoes, and cinder cones.
A Surtseyan eruption is an explosive style of volcanic eruption that takes place in shallow seas or lakes when rapidly rising and fragmenting hot magma interacts explosively with water and with water-steam-tephra slurries. The eruption style is named after an eruption off the southern coast of Iceland in 1963 that caused the emergence of a new volcanic island, Surtsey.
Mount Porndon is a 278-metre-high (912 ft) volcano located 13 kilometres southeast of Camperdown in western Victoria, Australia.
The Auckland Region of New Zealand is built on a basement of greywacke rocks that form many of the islands in the Hauraki Gulf, the Hunua Ranges, and land south of Port Waikato. The Waitākere Ranges in the west are the remains of a large andesitic volcano, and Great Barrier Island was formed by the northern end of the Coromandel Volcanic Zone. The main isthmus and North Shore are composed of Waitemata sandstone and mudstone, and portions of the Northland Allochthon extend as far south as Albany. Little Barrier Island was formed by a relatively isolated andesitic volcano, active around 1 to 3 million years ago.
Crater Hill is one of the volcanoes of the Auckland volcanic field, in New Zealand. It consists of an explosion crater about 600 metres (2,000 ft) wide, partly filled with water. The hill, alongside Māngere Lagoon, Waitomokia, Kohuora, Pukaki Lagoon and Robertson Hill, is one of the volcanic features collectively referred to as Nga Tapuwae a Mataoho, referring to the deity in Tāmaki Māori myths who was involved in their creation.
Little Rangitoto is a volcano in the Auckland volcanic field in Remuera, New Zealand. The name Maungarahiri refers to Rāhiri, an ancestor of Ngāpuhi, who journeyed around the North Island. In the 1700s and early 1800s, the volcano was the site of Ngāti Whātua-o-Ōrākei seasonal farms.
Purchas Hill is one of the volcanoes in the Auckland volcanic field.
Hampton Park is one of the volcanoes in the Auckland volcanic field. A small scoria cone reaching 35 metres above sea level, with a shallow crater around 50 metres wide, which has been modified by quarrying. The scoria cone sits in the centre of a much larger explosion crater, the eastern arc of the surrounding tuff ring is still present. Stone from the volcano was used to build dry-stone walls and the nearby St John's Church built on the tuff ring crest.
The Puhinui Craters are located in Auckland's Puhinui Reserve and are part of the Auckland volcanic field in the North Island of New Zealand. They were first recognised as volcanic craters in 2011. A cluster of three small maar craters like these is unique in the Auckland volcanic field. Their ages are unknown but most probably all three erupted during the same eruptive episode. They could have been associated with the eruption of nearby McLaughlins Mountain but this is speculation at present.
Te Tātua-a-Riukiuta is a volcano in Three Kings, New Zealand that erupted 28,500 years ago. The volcano had three prominent peaks and a number of smaller peaks until most of them were quarried away, leaving a sole remaining large peak called Big King.
Manzaz volcanic field is a volcanic field in Algeria. It consists of scoria cones with lava flows and has been active until recently.
Ubehebe Craters is a volcanic field in California. In northern Death Valley, it consists of 14-16 craters in a 3-square-kilometre (1.2 sq mi) area. The largest of these craters is the 800 metres (2,600 ft) wide and 235 metres (771 ft) deep Ubehebe Crater, but many of these craters are partially buried and thus poorly recognizable. Additional volcanic features present include a remnant of a scoria cone as well as a tuff cone.
Lunar Crater volcanic field is a volcanic field in Nye County, Nevada. It lies along the Reveille and Pancake Ranges and consists of over 200 vents, mostly small volcanic cones with associated lava flows but also several maars, including one maar named Lunar Crater. Some vents have been eroded so heavily that the structures underneath the volcanoes have been exposed. Lunar Crater itself has been used as a testing ground for Mars rovers and as training ground for astronauts.
