The Earth Story

California's Mojave Desert is being sliced apart by faults and has the occasional volcanic cinder cone found within it. Amboy Crater, near Interstate 40 and just outside of the air force base, is an extremely well preserved one, with loose rocks on the sides surrounded by lava fields from an eruption 79,000 years ago. Here it is explored from the air.

The Great Rift The mountains of Idaho are split by a wide valley known as the Snake River Plain. Much of this landscape was once volcanic, as massive eruptions associated with the Yellowstone Hot Spot blasted their way across the state over the past 20 million years, flattening the mountains as you see here. Every so often, molten rock associated with the Yellowstone system finds a new path it can take up to the surface, and none have been more active recently than the Great Rift.

Fissure 8, the Cinder Cone that produced the largest lava flows in the 2018 Kilauea eruption, is still steaming and barren today. Here’s a visit. 

Paricutín volcano famously was born out of a cornfield in Mexico in 1943 - perhaps the only time humans have ever seen a volcano like this. It lies in a "Monogenetic" field, meaning that volcanoes in this site tend to erupt once and then never again, leaving the landscape with whatever they put out during their eruption. This drone video explores Paricutín and the lava covered landscape surrounding it, including the remnants of two villages that were buried in the lava.

Waw an Namus — A Saharan volcano From these images captured by the Operational Land Imager (OLI) on Landsat 8, the dormant volcano Waw an Namus looks like a drop of ink on a dusty piece of parchment. Located in Saharan region of southwestern Libya, the jet-black patch is made up of volcanic ash that was produced during the volcano’s last eruption. Although we don’t know the eruption's exact date, we know that it likely erupted some time during the past few thousand years, since the volcanic ash hasn’t yet been weathered and eroded away by wind or water. At the center of volcano lies a 4-km wide caldera — a depression that forms when a volcano with a shallow magma chamber collapses after a volcanic eruption.

Mývatn Maars

When lava hits water, it tends to explode. The heat causes the water to flash to steam and expand, tearing the rock apart and blasting out fragments. Those fragments tend to pile up, forming cones around the location where the water and lava met.

Those cones are called maars (or rootless cones since they’re not connected to a magma system below) and this spot is loaded with them. This is Lake Mývatn in north-central Iceland, north of the volcano Krafla. The lake originally formed in a basin left behind after the end of the last glaciation – the basin was surrounded by glacial moraines that held in the water.

2300 years ago, a large fissure eruption took place north of the lake, sending lava all the way to the Arctic Ocean. The lava flow interacted with the waters in the lake, causing explosions and forming these maar volcanic cones.

That lava flow and repeated eruptions since then left their mark on the area, producing new cones and damming the lake at different edges.

The lake is the 6th largest in Iceland. Its waters freeze over in the winter and melt in the summer, setting up a eutrophic environment with heavy biological productivity. Algal blooms form in the summer, fed by nutrients from nearby springs that supply waters that are rich in nutrients and metals due to the hydrothermal systems nearby. Diatom-rich sediments from the lake are even dredged/mined as a resource in Iceland.

-JBB

Image credit: National Geographic Wallpaper http://travel.nationalgeographic.com/travel/365-photos/lake-mvatn-iceland/

Read more: https://notendur.hi.is/~arnie/geol.htm http://www.diamondringroad.com/myvatngeology.html http://www.hafro.is/Bokasafn/Greinar/oikos_32-82.pdf http://bit.ly/1B970zY

Relaxing on Green Sandy Beaches

What better way to escape than to travel to Hawai'i and kick off our shoes on a green sandy beach?

Green beaches are pretty rare; in fact, there are only four of them in the world. They're formed by olivine crystals that have eroded from cinder cones. For example, Papakolea beach in Hawai'i is composed of eroded olivine particles from a 49,000 year old cinder cone. Olivine is created when basalt lava is high in magnesium and iron. These two elements are rather heavy for sand, so they are left behind when other sand particles are carried away by waves, leaving green beaches. Olivine is very common in the mantle of the earth and throughout space. When Apollo 15 returned to earth they brought back a sample of lunar olivine. In addition, weathered olivine on Mars might be an indication that there was once water on the planet; olivine weathers quickly, leaving idingsite, a combination of clay minerals, iron oxides and ferrihydrites

Because olivine is so prevalent in Hawaiian lavas and because olivine is one of the first crystals to form as magma cools, it is often considered the "Hawaiian Diamond". When olivine is at its finest (or most pure), it forms the gem we call peridot.

Further reading: https://www.facebook.com/TheEarthStory/posts/511311338929915 Further reading on peridot:https://www.facebook.com/TheEarthStory/posts/555689177825464 Further reading: http://www.geologyin.com/2014/11/the-green-sand-beach-mahana-beach.html Picture of Papakolea Beach courtesy of: jonny-mthttp://commons.wikimedia.org/wiki/File:Papakolea_snapshot.jpg Olivine sand grain picture: photo © Brian W. Schallerhttp://en.wikipedia.org/wiki/File:A178,_Hawaii,_USA,_Papakolea_Green_Sand_Beach,_handful_of_sand,_2007.JPG

-Colter

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Flying a drone over lava flows and near a cinder cone volcano, Antofagasta province, Chile

Cinder cone on the edge of Etna Volcano, Sicily

Panorama of Amboy Crater, a recent cinder cone in California’s Mojave Desert

Drone vieow of a cinder cone on the edge of Lonquimay volcano, Chile. Original caption: