tashtab mountain is located 25 km from the city of khur in northeastern isfahan province. several bentonite mines formed in this area as a result of the eocene volcanic alteration. these mines are classified as the khur bentonite horizon. studies on trace elements in parent rock and clays show that the studied bentonites formed from andesite-basaltic parent rocks. the xrd analysis shows that st...

Five species of the rock-climbing, gobiid subfamily Sicydiinae are now known from Ponape, Eastern Caroline Islands, Micronesia, four of which are described herein as new: Sicyopus nigriradialus, Sicyoplerus lividus, Sicyopterus eudenlatus, and Sliphodon caeruleus. This increases the number of described freshwater/estuarine fish species from that volcanic island to 15. The fifth sicydiine specie...

Becker et al. (1) presented geochemical evidence that suggests that the largest mass extinction in Earth history, at the PermianTriassic boundary (PTB) 250 million years ago (Ma), coincided with an extraterrestrial impact comparable in size to the one that likely caused the end-Cretaceous extinctions 65 Ma (2). Although Becker et al. analyzed material from sections in Hungary, Japan, and China,...

introduction one of the factors affecting in the control of environmental hazards, is the stability of the structure landforms. human activities especially in the case transportation, and also the need to expand it in different areas, can significantly affect on the region geomorphologic structures and causing high damages on life and financial. as a result, human activity can operate as a fact...