sexta-feira, 21 de maio de 2010

Accretionary Wedge - Geo-Images

This year, the geoblogging carnival, The Accretionary Wedge,  will be held at Highly Allochthonous. The theme chosen is favorite geological images.

Here is the contribution of the "Geologia Marinha e Costeira" blog:
Beach-ridges - eastern Brazil. Each ridge shows a previous position of the shoreline
Miocene sediments onlaping the Precambrian basement. The Barreiras formation has widespread occurrence in eastern Brazil.
Recôncavo basin - tilted sedimentary rocks - these are cretaceous lacustrine sediments deposited in tectonic lakes formed in rift-valley basins during South America - Africa break up. Most of the oil presently extracted from the Brazilian continental margin was generated from organic matter deposited in these lakes.
Recôncavo basin - cretaceous synsedimentary deformation affecting lacustrine sediments.
Coastal erosion - shoreline retreat does not destroy recreational beaches. It just displaces them.
Dinosaur footprints - Mesozoic sediments - Maranhão - northern Brazil.
Ebb-tidal delta - eastern Brazil. Dark color results from the small river draining wetlands rich in humic acids.
São Francisco river sand bar - the image shows two episodes of deposition. The deposits of the older episode are partially covered with thin vegetation, but individual sand waves are still visible.
The São Francisco delta river mouth - a classical example of a wave-dominated delta
Sand waves in a small river bed
 Teredolites - ichnogenus of a trace fossil. Modern equivalent are the teredinid bivalves known as shipworms.

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