Friday Lifeform Geology Blogging
I’m bored with the usual lifeforms. There’s lots of nice invertebrates out there, and although I know if one is tired of invertebrates one’s tired of life, but I’ll save the spineless for another day. Geology is rocking my boat right now.
So, as it’s almost the holiday season, here’s a nice picture of salt glaciers in Iran.
Yes, I did say salt glaciers. I found these pictures while idly researching the Afar Depression, apropos of the 8 metre wide crack that has appeared there consequent to a number of earthquakes, notably those at Bandar Aceh, in the Hindu Kush, and in Iran.
The Afar depression, showing active rifting.
Scientists say they have witnessed the possible birth of a future ocean basin growing in north-eastern Ethiopia. The team watched an 8m rift develop in the ground in just three weeks in the Afar desert region last September. It is one small step in a long-term split that is tearing the east of the country from the rest of Africa and should eventually create a huge sea. The UK-Ethiopian group says it was astonished at the speed with which the 60km-long fissure developed. “It’s the first large event we’ve seen like this in a rift zone since the advent of some of the space-based techniques we’re now using, and which give us a resolution and a detail to see what’s really going on and how the earth processes work; it’s amazing,” said Cindy Ebinger, from Royal
Holloway University of London.
It looks as though the Indian Ocean plate is turning anticlockwise, and at the Persian Gulf that and 2 other plates come together, butting up against the Indian Ocean plate to form a tripartite plate junction. It’s here, where the Great Rift Valley disappears into the Gulf, that the Afar Depression is widening to form a new ocean. The plate pressure is what’s causing the salt glaciers.
How the salt glaciers formed:
The diapirs, or salt plugs, in this image are a few of over 200 similar features scattered about this part of the Zagros Mountains in southern Iran. This region of folded rocks is the result of the collision between the Asian landmass and the Arabian platform. The deeper underlying deposits of salt have been reformed into ascending fluid-like, plastic plumes of salt. In some places these plumes have pushed through the overlying rock units, like toothpaste extruding from a tube, and are now visible as darkish irregular patches.
Gravity has caused the salt to flow into adjacent valleys; the resulting tongue-shaped bodies, more than 5 km long, resemble glaciers, with arcuate ridges separated by crevasse-like gullies and with steep sides and fronts. The darker tones are due to clays brought up with the salt, as well as the probable accumulation of airborne dust. This ASTER perspective view was created by draping a band 3-2-1 (RGB) image over an ASTER-derived DEM (2x vertical exaggeration), and was acquired on August 10, 2001.
Image courtesy NASA/GSFC/METI/ERSDAC/JAROS,
and U.S./Japan ASTER Science Team
This is a beautiful site – amazing satellite images of geological, archaeological and other features, and all public access. The thought of salt deposits being extruded like toothpaste from a tube pleases me greatly.
I’ve been looking for some copyright-free satellite images to have enlarged to about a metre square for framing, and these are perfect. Education and aesthetics, the ideal combination.
