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L45 Turbidity flow structures on rock. Cornwall, UK
Position:
N50° 46'
W04° 34' approx.
Elevation:
at sea level
Image format:
LF MF 35mm
FOSSILIZSED MUD SLIDES
This rock that formed on the sea bed about 300 million years ago.
River poured huge volumes of dust and grit into the ocean. Piles
of sediment built up. Every so the piles of sediment would collapse
when they grew too large. Clouds of sediment flow across the sloping
sea bed, finally running out of energy and settling on the sea
bed. Larger particles settled first forming sand deposits while
smaller, clay particles settled on top.
Then along comes another flow. The first deposit is ERODED by
the new flow. Larger stones in the base of the flow cut deep grooves
in the older surface. Then more sand and mud settled, preserving
what was left of the first flow. Preserving, in fact, even the
grooves that were cut. This view shows two such grooves and a
host of other flow marks (looking just like tongues) and marks
the passage of a mud and grit flows on an ancient sea bed. The
hammer provides an idea of scale. Images L44 & L46 show other views of these interesting features.
More detail
Image Trail:
L44 Folded rock. Cornwall, UK
L46 Fossilized ripple marks on titled rock beds. Cornwall, UK
Links:
www.elnino.usgs.gov/landslides-sfbay/photos.html
www.wwwdwatcm.wr.usgs.gov/fs_landslide.html
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