Three voluminous rhyolitic ignimbrites have been identified along the southern margin of the central Snake River Plain. As a result of wide-scale correlations, new volume estimates can be made for these deposits: ~350 km for the Steer Basin Tuff and Cougar Point Tuff XI, and ~1,000 km for Cougar Point Tuff XIII. These volumes exclude any associated regional ashfalls and correlation across to th...

Sites containing Acheulian, Sangoan, Fauresmith, and Middle Stone Age artefacts occur within and below the Bedded Tuff, a widespread volcaniclastic member of the Kapthurin Formation, Kenya. The Bedded Tuff eruptive complex consists of up to twelve tephra beds, intercalated sediments, and paleosols. Two pumiceous units, high in the Bedded Tuff sequence, have been dated by(40)Ar/(39)Ar, one to 23...

Phillipsite tuff samples from Jebal Aritayn (Jordan) was treated chemically by acid, base, and salt and thermally at 200 and 400 oC. Both treated and untreated phillipsite samples were titrated with HCl and NaOH. The potentiometric titration curves showed that Jordanian phillipsite tuff exists in the base form (pH 8.5) and thus has a remarkable buffering capacity toward H. The effect of chemica...

Rhizobium sp. H41 isolated from weathered tuff can weather tuff and release Fe, Si, and Al from the rock under nutrient-poor conditions. Here, we report the draft genome sequence of strain H41, which may facilitate a better understanding of the molecular mechanism involved in rock weathering by the bacterium.

An exploratory hole UE25a-1) was drilled at Nevada Test Site NTS) to determine the suitability of pyroclastic deposits as storage sites for radioactive waste. Studies have been conducted to investigate the stratigraphy, structure, mineralogy, petrology, and physical properties of the tuff units encountered in the drill hole. This report deals with the interpretation of physical properties for t...

The Whistler Squat Quarry (TMM 41372) of the lower Devil's Graveyard Formation in Trans-Pecos Texas is a middle Eocene fossil locality attributed to Uintan biochronological zone Ui1b. Specimens from the Whistler Squat Quarry were collected immediately above a volcanic tuff with prior K/Ar ages ranging from ∼47-50 Ma and below a tuff previously dated to ∼44 Ma. New 40Ar/39Ar analyses of both of ...