Tephra

Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from a single eruption—to create a chronological framework in which paleoenvironmental or archaeological records can be placed.

Tephra is any sized or composition pyroclastic material produced by an explosive volcanic eruption and precise geological definitions exist.

[2] It consists of a variety of materials, typically glassy particles formed by the cooling of droplets of magma, which may be vesicular, solid or flake-like, and varying proportions of crystalline and mineral components originating from the mountain and the walls of the vent.

Ash damages communication and electrical systems, coats forests and plant life, reducing photosynthesis, and pollutes groundwater.

Nearby watersheds and the ocean can experience elevated mineral levels, especially iron, which can cause explosive population growth in plankton communities.

For example, carbonatite tephra found at Oldoinyo Lengai (a volcano in the East African Rift Valley) has buried and preserved fossilized footprints of humans near the site of the eruption.

[citation needed] Volcanic eruptions around the world have provided valuable scientific information on local ecosystems and ancient cultures.

[11] After the 2011 eruption, fossils of single-celled marine organisms were found in the restingolites verifying the origin theory that Canary Island growth comes from a single buoyant jet of magma from the Earth's core instead of cracks in the ocean floor.

A team of scientists directed by Dr. Clive Oppenheimer, British volcanologist, discovered a larch trunk embedded within Paektu Mountain.

[15] In northeastern China, a large volcanic eruption in the early Cretaceous caused the fossilization of an entire ecosystem known as the Jehol Biota when powerful pyroclastic flows inundated the area.

Earlier, in 79 AD, in an eruption which lasted 12 to 18 hours, Vesuvius had covered the city of Pompeii in molten lava, ash, pumice, volcanic blocks, and toxic gases.

[20] In 2006, the Augustine Volcano in Alaska erupted generating earthquakes, avalanches, and projected tephra ash approximately two hundred and ninety kilometers away.

[22] Due to the location of the subduction zone of the eastern Pacific's Nazca Plate, there are twenty one active volcanoes in southern Peru.

[23] In 2006, fossils, found under a layer of volcanic ash in Peru, were excavated by a team of paleontologists led by Mark D. Uhen, professor at George Mason University.