Four bacterial species isolated from the rhizoplane of cacti growing in bare lava rocks were assessed for growth promotion of giant cardon cactus seedlings (Pachycereus pringlei). These bacteria fixed N(2), dissolved P, weathered extrusive igneous rock, marble, and limestone, and significantly mobilized useful minerals, such as P, K, Mg, Mn, Fe, Cu, and Zn in rock minerals. Cardon cactus seeds ...

 Igneous Rocks form from the solidification of molten rock. Intrusive igneous rocks are composed of crystals that are large enough to be seen with the naked eye because these rocks cooled slowly, deep within the Earth thereby allowing time for the crystals to grow. In contrast, extrusive (volcanic) igneous rocks cool very quickly after they erupt from a volcano, and so are composed of microsco...

Dense layers of bacteria and fungi in the rhizoplane of three species of cactus (Pachycereus pringlei, Stenocereus thurberi, Opuntia cholla) and a wild fig tree (Ficus palmeri) growing in rocks devoid of soil were revealed by bright-field and fluorescence microscopy and field emission scanning electron microscopy. These desert plants are responsible for rock weathering in an ancient lava flow a...

O are claimed to be pieces of ocean crust and upper mantle that have been thrust up onto continental crust and are now found in mountains, mainly along continental margins.1,2 An ideal ophiolite suite consists from bottom to top of peridotite, gabbro, sheeted dikes, basalt with pillow lavas and sedimentary rocks. The peridotite is considered to be an upper mantle rock, while the remainder of th...

[1] High-resolution images of the walls exposed in Valles Marineris reveal variations in appearance and degree of layering indicating various lithologies comprise the Tharsis plateau. The layered wall rock has been proposed to result from effusive flood basalt volcanism or interbedded sediments and volcanics. We present observations of unlayered rock that indicate layering extends to a greater ...

Abstract The vast majority of extrusive carbonatites are calcitic rocks which may be confused with sedimentary limestones, thus requiring a disambiguation criterion. Extrusive classified based on quantitative criteria that tend to avoid genetic mechanisms. Carbonatite nomenclature is in progress but regulated by the International Union Geological Sciences norm for igneous rocks. Carbonate rock ...

The Gruithuisen and Mairan domes on the moon represent morphologically and spectrally distinct nonmare extrusive volcanic features of Imbrian age. The composition, morphology, and age relationships of the domes indicate that nonmare extrusive volcanism in the northern Procellarum region of the moon continued until about 3.3 x 10(9) to 3.6 x 10(9) years ago and was partially contemporaneous with...