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User Name Thread Name Subject Posted
leeneia BS: ancient meteorite in (5) RE: BS: ancient meteorite in 21 Jun 19

If you click on the link in the OP, you will see an intriguing photograph. The DH and I argued about what it all meant, so I tracked down the author of the scientific paper and asked some questions. Behold his reply!
"The layers of barnacle-covered rock just above the inlet are Stoer Group (Torridonian) sandstone. These were deposited by rivers in a semi-arid environment, in an active rift valley. Typical depositional environment was shallow lakes that frequently dried out, evidenced by ripple marks and desiccation mud cracks.

Above this is the purplish-red unit, that contains large slabs of deformed pink sandstone. This is the impact debris deposit, about 11 meters thick at this location. It contains about 5% meteoritic material.

Beyond this in the background to upper left are purplish red lake sediments.

The impact deposit is distinguished by centimeter sized, green flakes of devitrified melt glass, and occasional decimeter sized blocks of Lewisian gneiss.

The evidence presented in our recent paper published in the Journal of the Geological Society is that the asteroid hit the sandstone sediments in the rift valley, about 15-20km away from this outcrop.

The Torridonian sandstones were deposited in at least two episodes separated by about 200million years. The Stoer Group was first recognized by Sandy Stewart in the 1960s and was deposited 1.2 billion years ago, the radiometric age obtained for the impact deposit. These Precambrian sandstones are remarkably well preserved and escaped being covered by the meta-sediments (Schists) of the Moine Thrust 430 million years ago.

Hope this is useful."

Just think, green flakes from a meteorite that hit 1,200,000,000 years ago! And the sandstone - still looking like sandstone after all this time.

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