Mud volcanoes, unlike many others, do not extrude lava. Instead, they release glutinous bubbling brown slurry of mineral-rich water and sediment. They range in size from several kilometres across, to less than a metre – the little ones are known as mud pots, reflecting their diminutive nature. The world’s largest, though, is Lusi: a mud volcano …[Read More]
Geochemistry, Mineralogy, Petrology & Volcanology
Geosciences Column: The Toba eruption probably did have a global effect after all
Almost everyone has heard of the Toba super-eruption, which took place on the island of Sumatra roughly 74,000 years ago, but the only evidence of tephra or tuff (volcanic fragments) from the eruption is in Asia, with nothing definite further afield. It has sometimes been thought that this huge eruption may have led to a …[Read More]
Geosciences Column: From the desolate to the diverse, a story of volcanic succession
When a volcano erupts and spews lava onto the surrounding terrain, it is merciless in its destruction. All that is green on the land is engulfed in flame, or buried by an insurmountable mass of molten rock. Whatever charred remains of what lies beneath it will not see the light of day once the lava …[Read More]
Imaggeo on Mondays: Turkey’s cotton castle
This week, Imaggeo on Mondays is brought to you by Josep Ubalde, who transports us to a wonderful site in western Turkey: a city of hot springs and ancient ruins dubbed cotton castle, after the voluminous white rocks that spread from the spring’s centre… Pamukkale is lies in Turkey’s inner Aegean region, within an active fault …[Read More]
Imaggeo on Mondays: Quartz lawns and crystal flowers
Petrologists spend a large part of their time peering down microscopes at wafer thin slices of rock to work out what they’re made of and how they were formed. What lies on the other side of the lens can be an incredibly beautiful pattern, a kaleidoscope of colour, or stark bands of black and white, …[Read More]
Imaggeo on Mondays: Villarrica Volcano
This week’s Imaggeo on Mondays highlights the vulnerability of Villarrica’s slopes and zooms in on the volcano’s spectacular crater… Villarrica, one of the largest stratovolcanoes in Chile, is also one of the country’s most active. The volcano is iced by glaciers that make the mountain a stunning scene, but also a dangerous one. The glaciers cover some …[Read More]
Imaggeo on Mondays: Volcanic rope
On Hawaii, lava fields fall into two camps – pahoehoe and a’a. This week’s Imageo on Mondays puts the two into perspective… Pahoehoe fields are created when the lava is well insulated at the surface. The cooled rock on top prevents a lot of heat escaping and lets the lava flow beneath a tough skin …[Read More]
Imaggeo on Mondays: A rolling stone gathers no moss
Philippe Leloup brings us this week’s Imaggeo on Mondays, with tales from a mountain trail that show a geologist can never resist a good rock! This image is that of a polished slab of a rock composed of interlayered marbles and amphibolites. The sample was once part of a small dry-stone wall bordering an outdoor …[Read More]
Imaggeo on Mondays: Rockscape
A geologist out in the field is often the one doing the mapping, but sometimes you might just find a map while you’re out there. Martin Reiser shares how he stumbled one such stunning feature… The picture shows colourful marly layers in a Triassic limestone of northwest Albania (Lezhe region). The marly layers have developed …[Read More]
Imaggeo on Mondays: Exploring the East African Rift
This week’s Imaggeo on Mondays is brought to you by Alexis Merlaud, an atmospheric scientist from the Belgian Institute for Space Aeronomy. While the wonders of the African atmosphere feature in his photography, the East African Rift has a much bigger tale to tell. Drawing from all aspects of geoscience Alexis shares its story… This …[Read More]