One of the most important natural hazards that threatens Caracas, the capital city of Venezuela, is the seismic hazard, due to its location in the plate boundary zone between the South America and the Caribbean plates. There is historic evidence for several destructive earthquakes in Caracas since 1641, being the most recent one the 1967 Caracas earthquake. This magnitude 6.5 earthquake which o...

Subseafloor sedimentary environments harbor remarkably diverse microbial communities. However, it remains unknown if the deeply buried fossils in these sediments play ecological roles in deep microbial habitats, or whether the microbial communities inhabiting such fossils differ from those in the surrounding sediment matrix. Here we compare the community structures of subseafloor microbes in co...

The atmospheres of solid planets exert a fundamental control on their surfaces. Interactions between atmospheric and geologic processes influence the morphology and composition of surfaces, and over the course of geologic time determine the historical evolution of the planet’s surface environments including climate. In the case of Earth, the origin of life likely occurred within surface environ...

in this study, we used teleseismic data which was recorded by 5 stations (dhr, ghg, kom, lin and vis) of the kermanshah seismic network from 2003 to 2007 with mb?5.5 and epicentral distances from 30° to 95°. the crustal structure beneath these stations was determined by the modeling of the p receiver functions. the main phases, which were observed in our final p receiver functions, are moho con...

this research was performed to determine the efficiency effect of sedimentary environment of kerman city area on soil structure bycomparing natural and reconstituted consolidation curves. in this regard, four different criteria such as sensitivity strength, stresssensitivity, schmertman criteria and the result of the uniaxial compression test were used. the base of these criteria is to compare ...

the kashkan formation (paleocene to middle eocene), consists of conglomerate, sandstone, and siltstone in the zagros folded zone, southwest iran. type of the sedimentary facies, architectural elements and trace fossils show that kashkan deposits were formed in a low sinuosity braided stream system, with north to south flow direction. the formation displays coarsening-upward succession reflects ...

________________________________________ Introduction __ ___________________________________ Area covered.__________________________________ Aeromagnetic survey.___________________________ Gravity survey.________________________________ Acknowledgments--.. __1________________________ Geology __ __ ____________ _ Rock units_____________________________________ Carboniferous and older rocks._____...

Landforms representative of sedimentary processes and environments that occurred early in martian history have been recognized in Mars Global Surveyor Mars Orbiter Camera and Mars Odyssey Thermal Emission Imaging System images. Evidence of distributary, channelized flow (in particular, flow that lasted long enough to foster meandering) and the resulting deposition of a fan-shaped apron of debri...

Three main features of paleosols are useful for distinguishing them from enclosing rocks: root traces, soil horizons, and soil structures. Fossil root traces are best preserved in formerly waterlogged paleosols. In oxidized paleosols their organic matter may not be preserved, but root traces can be recognized by their irregular, tubular shape, and by their downward tapering and branching. Often...

Many sedimentary rocks are formed by migration of sand ripples. Thin layers of coarse and fine sand are present in these rocks, and understanding how layers in sandstone are created has been a longstanding question. Here, we propose a mechanism for the origin of the most common layered sedimentary structures such as inverse graded climbing ripple lamination and cross-stratification patterns. Th...