Ignimbrite in the context of Rhyolite

Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "pyroclastics," and these are also technically sedimentary rocks.

Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earth's current land surface.

A pyroclastic fall deposit is a uniform deposit of material which has been ejected from a volcanic eruption or plume such as an ash fall or tuff. Pyroclastic fallout deposits are a result of:

1. Ballistic transport of ejecta such as volcanic blocks, volcanic bombs and lapilli from volcanic explosions
2. Deposition of material from convective clouds associated with pyroclastic flows such as coignimbrite falls
3. Ejecta carried in gas streaming from a vent. The material under the action of gravity will settle out from an eruption plume or eruption column
4. Ejecta settling from an eruptive plume or eruption column that is displaced laterally by wind currents and is dispersed over great distances

The Bandelier Tuff is a geologic formation exposed in and around the Jemez Mountains of northern New Mexico. It has a radiometric age of 1.85 to 1.25 million years, corresponding to the Pleistocene epoch. The tuff was erupted in a series of at least three caldera eruptions in the central Jemez Mountains.

The Bandelier Tuff was one of the first ignimbrites recognized in the geologic record, and has been extensively studied by geologists seeking to understand the processes involved in volcanic supereruptions.

Fiamme are lens-shapes, usually millimetres to centimetres in size, seen on surfaces of some volcaniclastic rocks. They can occur in welded pyroclastic fall deposits and in ignimbrites, which are the deposits of pumiceous pyroclastic density currents. The name fiamme comes from the Italian word for flames, describing their shape. The term is descriptive and non-genetic.

Fiamme are most typical of welded lapilli-tuffs and are commonly found in association with eutaxitic textures, best seen under the microscope.

Kurile Lake (Russian: Кури́льское о́зеро, romanized: Kuríl'skoye Ózero) is a caldera and crater lake in Kamchatka, Russia. It is also known as Kurilskoye Lake or Kuril Lake. It is part of the Eastern Volcanic Zone of Kamchatka which, together with the Sredinny Range, forms one of the volcanic belts of Kamchatka. These volcanoes form from the subduction of the Pacific Plate beneath the Okhotsk Plate and the Asian Plate.

Before the Kurile Lake caldera formed, the Pauzhetka caldera was active during the Pleistocene, and was the origin of the Golygin ignimbrite at 443,000 ± 8,000 years old. The Kurile Lake caldera erupted 41,500 years ago, and another small eruption occurred between 9,000 and 10,000 years ago; then in 6460–6414 BCE, a very large eruption took place, forming the present-day caldera and the Kurile Lake ignimbrite and depositing ash as far as 1,700 kilometres (1,100 mi) away. This eruption has a volume of 140–170 cubic kilometres (34–41 cu mi), making it a VEI-7-class eruption and one of the largest during the Holocene. Subsequently, the volcanoes Diky Greben and Ilinsky grew around the caldera; as of 2024, the most recent eruption from Ilinsky was in 1911. The caldera is filled by a lake with an area of 76 square kilometres (29 sq mi), and a maximum depth of 316 metres (1,037 ft). The largest sockeye salmon stocks in Asia live in the lake.

Patrick Marshall (22 December 1869 – November 1950) was a geologist who lived in New Zealand. He was the first to introduce the terms rodingite and ignimbrite into petrology and mineralogy. Marshall's most significant contribution to science was his work on coastal erosion and volcanology.

Pantellerite is a type of volcanic rock, specifically a peralkaline rhyolite. It has a higher iron and lower aluminium composition than comendite. It is named after Pantelleria, a volcanic island in the Strait of Sicily and the type location for this rock. On Pantelleria the rock is usually found as a vitrophyre containing phenocrysts of anorthoclase or sanidine. Quartz is found only in the most strongly peralkaline rocks. Mafic minerals may include aegirine, fayalite, aenigmatite, ilmenite, and sodic amphibole (often arfvedsonite or ferrorichterite).

The Yellowstone Caldera, also known as the Yellowstone Plateau Volcanic Field, is a Quaternary caldera complex and volcanic plateau spanning parts of Wyoming, Idaho, and Montana. It is driven by the Yellowstone hotspot and is largely within Yellowstone National Park. The field comprises four overlapping calderas, multiple lava domes, resurgent domes, crater lakes, and numerous bimodal lavas and tuffs of basaltic and rhyolitic composition, originally covering about 17,000 km (6,600 mi).

Volcanism began 2.15 million years ago and proceeded through three major volcanic cycles. Each cycle involved a large ignimbrite eruption, continental-scale ash-fall, and caldera collapse, preceded and followed by smaller lava flows and tuffs. The first and also the largest cycle was the Huckleberry Ridge Tuff eruption about 2.08 million years ago, which formed the Island Park Caldera. The most recent supereruption, about 630,000 years ago, produced the Lava Creek Tuff and created the present Yellowstone Caldera. Post-caldera eruptions included basalt flows, rhyolite domes and flows, and minor explosive deposits, with the last magmatic eruption about 70,000 years ago. Large hydrothermal explosions also occurred during the Holocene.

Mount Batur (Indonesian: Gunung Batur; Balinese: ᬕᬸᬦᬸᬂᬩᬢᬸᬃ, romanized: gunung batuŕ) is an active volcano located at the center of two concentric calderas northwest of Mount Agung on the island of Bali, Indonesia. The southeast side of the larger 10×13 km caldera contains a caldera lake. Both the larger caldera, and a smaller 7.5 km caldera were formed by a collapse of the magma chamber, the first larger collapse taking place about 29,300 years ago, and the second inner caldera collapsing about 20,150 years ago. Another estimate of the inner caldera's formation date, formed during the emplacement of the Bali (or Ubud) ignimbrite, has been dated at about 23,670 and 28,500 years ago.

The first documented eruption was in 1804 and the most recent was in 2000.

The Ethiopia-Yemen Continental Flood Basalts were erupted during the Oligocene. They cover an area of about 600,000 km in Yemen and Ethiopia, with an estimated volume of greater than 350,000 km. They are associated with the Afar Plume and the initiation of rifting in the southern Red Sea and Gulf of Aden.

In Ethiopia flood basalts cover an old erosion surface with occasional flat areas or peneplains. Burial of old surfaces by lava has preserved laterite soils in both Yemen and Ethiopia.