Rhyolite is a volcanic rock with high silica content.

This is a volcanic ridge.

These features are volcanic in origin.

One possible source is volcanic activity.

Efforts to establish the calendar date of the volcanic eruption have been extremely controversial.

No life without tectonic activity, without volcanic activity.

The volcanic nature of the island has attracted scuba divers.

About 3,000 years ago, Mount Hakone produced a volcanic explosion which resulted in Lake Ashi on the western area of the prefecture.

Today, the lake also poses a threat because its natural wall is weakening.

This is closely related to tectonic and volcanic activity of planets.

The island's volcanic origin is manifested in several hot springs and the two gulfs.

Several lines of evidence point to ongoing volcanic activity on Venus.

Earthquakes can also trigger landslides, and occasionally volcanic activity.

The region first became volcanically active around 3 4 million years ago, though volcanism on Thera began around 2 million years ago with the extrusion of dacitic lavas from vents around the Akrotiri.

The stories as to the ancestors of the Tuvaluans vary from island to island.

One possibility is that ash from a volcanic eruption was generating the lightning.

Geology and landscape Cocos Island is an oceanic island of both volcanic and tectonic origin.

There are features that may be volcanic in origin, disgorging water mixed with ammonia onto the surface.

Cozumel is a flat island based on limestone, resulting in a karst topography.

This is clearly demonstrated by two eruptions, Agung (1963) and El Chichón (1982).

c. 5677 BC Cataclysmic volcanic eruption of high Mount Mazama creates Oregon's Crater Lake when the resulting caldera fills with water.

There is some evidence to suggest that the city was a colony of one of the cities of the center of Mexico.

The Philippine Institute of Volcanology and Seismology released a status report on Mayon s volcanic activity Alert Level 3 is in effect over Mayon, which means that the 6 km radius Permanent Danger Zone around the volcano and the 7 km Extended Danger Zone on the southeast flank of the volcano should be free from human activity because of sudden explosions that may generate hazardous volcanic flows

Most of this salt was released from volcanic activity or extracted from cool igneous rocks.

Surface geology Much of the Venusian surface appears to have been shaped by volcanic activity.

It discovered a few rings around Jupiter, as well as volcanic activity on the moon Io.

Hematite can also occur without water, however, usually as the result of volcanic activity.

Xeréu beachDue to the depth of the water, this beach is suitable for diving and also for fishing.

Less common is basalt, a denser volcanic rock that is the primary constituent of the ocean floors.

The remains of an ancient atoll as a hill in a limestone area is called a reef knoll.

Like the rest of the Canary Islands, it is of volcanic origin.

Earthquakes, volcanic activity, mountain building, and oceanic trench formation can occur along these plate boundaries.

It is long (southwest northeast) and in area, partly covered by glaciers (an area of around the Beerenberg).

The Samoan islands have been produced by vulcanism, the source of which is the Samoa hotspot which is probably the result of a mantle plume.

Volcanic activity on the Jovian moon Io (see below) injects gas into Jupiter's magnetosphere, producing a torus of particles about the planet.

Nature The Nicobar Islands are part of a great island arc created by the collision of the Indo Australian Plate with Eurasia.

Volcanic activity, cometary impacts, and the presence of methanogenic microbial life forms are among possible sources.

It is the youngest island in the Lesser Antilles, still being formed by geothermal volcanic activity, as evidenced by the world's second largest hot spring, Boiling Lake.

A volcano is a rupture on the crust of a planetary mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

It has 325 islands which cover an area of , with the Andaman Sea to the east between the islands and the coast of Burma.

The distinguishing feature of phreatic explosions is that they only blast out fragments of pre existing solid rock from the volcanic conduit no new magma is erupted.

On November 4, 1957 a second volcanic event occurred rapidly, forming a second island, and by the 12 November 1957 an isthmus had formed linking Faial.

It has volcanoes on it. And that's Mount Olympus on Mars, which is a kind of huge volcanic shield on that planet.

The Mascarene Islands (Mauritius, Réunion, and Rodrigues), are of volcanic origin and are less than 10 million years old.

Geography The archipelago of the Desertas Islands is a chain of three long and narrow islands that stretch over a north south distance of .