* Terrigenous deposits with land origins, consisting of sand, mud, and rock particles formed by erosion, weathering, and volcanic activity on land washed to sea.

Despite the harshness of winter in most parts, the fertility of the plateau's volcanic soil made Armenia one of the world's earliest sites of agricultural activity.

These formations became exposed when the ocean floor was raised by a major volcanic activity in the Devonian forming much of the east coast of Australia.

At the Alphonsus, three scientific objectives were determined to be of primary interest and paramount importance: the possibility of old, pre-Imbrium impact material from within the crater's wall, the composition of the crater's interior and the possibility of past volcanic activity on the floor of the crater at several smaller " dark halo " craters.

At that point, scientists began to reconsider their pre-mission hypothesis that Descartes had been the setting of ancient volcanic activity, as the two astronauts had yet to find any volcanic material.

There are also natural mechanisms for variation including climate oscillations, changes in solar activity, variations in the Earth's orbit, and volcanic activity.

* Natural forces alone ( such as solar and volcanic activity ) cannot explain the observed warming.

sometimes referred to as ' the hinge of Africa ;' throughout the country there are areas of thermal springs and indications of current or prior volcanic activity ; Mount Cameroon, the highest mountain in Sub-Saharan west Africa, is an active volcano

This trend was due to intense volcanic activity which produced large quantities of carbon dioxide.

Scientists hypothesize that the K – Pg extinctions were caused by one or more catastrophic events, including at least one asteroid impact ( especially the one that created the Chicxulub crater ) or increased volcanic activity.

Several impact craters and massive volcanic activity, such as that in the Deccan Traps, have been dated to the approximate time of the extinction event.

Many researchers believe the extinction was more gradual, resulting from the sea level and climate changes already occurring during the late Cretaceous, and aggravated by impact events or increased volcanic activity.

Increases in greenhouse gases, such as by volcanic activity, can increase the global temperature and produce an interglacial.

Through volcanic activity due to thermal expansion this continent broke and the new continents drifted away from each other because of further expansion of the rip-zones, where the oceans now lie.

If volcanic activity continues, the centre of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galán, Lake Toba, Yellowstone, and so on, by subsequent intrusion of magma.

None of these worlds have plate tectonics, which contributes approximately 60 % of the Earth's volcanic activity ( the other 40 % is attributed to hot spot volcanism ).

The craters of the moon have been well preserved through time and were once thought to have been the result of extreme volcanic activity, but instead were formed by meteorites, nearly all of which took place in the first few hundred million years after the Moon formed.

The volcanic activity of Mars is concentrated in two major provinces, Tharsis and Elysium.

Current theories as to the cause of this dramatic drop in levels rule out volcanic activity ; therefore, it may have been a seismic event.

The motion of these plates causes the area's earthquake and volcanic activity.

El Salvador is known as the " Land of Volcanoes "; there are frequent and sometimes very destructive earthquakes and volcanic activity ; catastophic hurricanes are uncommon.

Earthquakes can also trigger landslides, and occasionally volcanic activity.

Earthquakes are caused mostly by rupture of geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests.

The name stems from the water's white-gray color, a function of eroded sand, clay, and volcanic ash carried by the river.

Rock wall foundations and beam holes and " cavates " carved into volcanic tuff remain from upper floors.

Amethyst is produced in abundance from the state of Minas Gerais in Brazil where it occurs in large geodes within volcanic rocks.

* 1986 – Carbon dioxide gas erupts from volcanic Lake Nyos in Cameroon, killing up to 1, 800 people within a 20-kilometer range.

The first deposit on the wall of a cavity, forming the " skin " of the agate, is generally a dark greenish mineral substance, like celadonite, delessite or " green earth ", which are rich in iron probably derived from the decomposition of the augite in the enclosing volcanic rock.

Other volcanic peaks rise from the floor of the valleys, some of the Kirunga ( Mfumbiro ) group, north of Lake Kivu, being still partially active.

Geologists believed prior to the mission that both of these formations were volcanic in origin ; however, samples returned from the lunar surface have since proven this hypothesis is incorrect.

Samples obtained from this boulder delivered the final blow to the pre-mission volcanic hypothesis, proving it incorrect.

The most detailed illustrations are to be found on the ' ship fresco ' at Akrotiri on the island of Thera ( Santorini ) preserved by the ash fall from the volcanic eruption which destroyed the town there.

* Cinder cone, a steep conical hill of volcanic fragments around and downwind from a volcanic vent

In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain.

Non-explosive volcanic craters can usually be distinguished from impact craters by their irregular shape and the association of volcanic flows and other volcanic materials.

While rocks melted by the impact resemble volcanic rocks, they incorporate unmelted fragments of bedrock, form unusually large and unbroken fields, and have a much more mixed chemical composition than volcanic materials spewed up from within the Earth.

The country's central spine, a northwest-southeast axis of steep volcanic slopes and deep gorges, generally varies in elevation from above sea level.

A narrow plain extends from the coastal volcanic range to the Pacific Ocean.

Bad harvests ( caused in part by extreme weather from El Niño along with volcanic activity at Laki and Grímsvötn in 1783 – 1784 ), rising food prices, and an inadequate transportation system that hindered the shipment of bulk foods from rural areas to large population centers contributed greatly to the destabilization of French society in the years leading up to the Revolution.

Fuerteventura is the oldest island in the Canary Islands dating back 20 million years to a volcanic eruption from the Canary hotspot.

islands vary geologically from high mountainous islands to low, coral atolls ; volcanic outcroppings on Pohnpei, Kosrae, and Truk