In a recent issue of PNAS, Zheng et al. (1) report a “Late Oligocene–Early Miocene age” of the Taklimakan Desert in northwest China. Their age was based on Ar/Ar dating of biotites and U–Pb dating of zircons from layers within the Xiyu Formation, which they interpreted as “volcanic ash.” This chronology effectively extends the formation of the Taklimakan Desert from ∼5 Ma, as recently reported ...

Within the volcanological community there is a growing awareness that many large- to small-scale, point-source eruptive events can be fed by multiple melt bodies rather than from a single magma reservoir. In this study, glass shard major- and trace-element compositions were determined from tephra systematically sampled from the outset of the Puyehue-Cordón Caulle (PCC) eruption (~1 km(3)) in so...

Fourteen microprobe analyses of basaltic glasses from three drill sites plus two dredged samples from the seafloor at the mouth of the Gulf of California suggest that magmatic liquids that cooled to form the volcanic crust in the Gulf of California have been fractionated, whereas other, more primitive submarine basalts from the Mid-Oceanic Ridge (MOR) have not. The limited chemical diversity am...

A Permian bentonite deposit at Melo, Uruguay is composed of a calcite-cemented sandstone containing clay pseudomorphs of glass shards (0-0.50 m) overlying a pink massive clay deposit (0.50-2.10 m). The massive bed is composed of two layers containing quartz and smectite or pure smectite respectively. The smectite is remarkably homogeneous throughout the profile: it is a complex mixed layer comp...

The 2010 eruption of Eyjafjallajökull (Iceland) and the 2011 eruptions of Grimsvötn (Iceland), Cordon Caulle (Chile) and Nabro (Ethiopia) have drastically heightened the level of awareness in the general population of how volcanic activity can affect everyday life by disrupting air travel. The ingestion of airborne volcanic matter into jet turbines may cause harm by (1) abrasion of engine parts...