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Frozen memories
of a tropical lagoon
Green rocks recall a warm, tropical lagoon
that was too saline to support life...
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About
200 yards further on you will see rocks that tell of a different
environment. We are now at what used to be the bottom of a warm,
tropical lagoon.
The clue is again in the colour.
The greeny-grey colour is caused by iron reacting with oxygen but
with less oxygen than created the red in the earlier section. That
reduced amount of oxygen is found in water.
There is no fossil evidence of life in these rocks so the water
was probably also very salty, as would be found in a lagoon, a lagoon
that was shallow and in a warm climate.
As you walk you can see that the rocks are in layers tilted towards
the north.
The first layers you can see were formed from the
first sediments that settled on the bottom of that ancient lagoon
and the furthest layer is the last one. So as you walk the rocks
get younger.
The layers of rock were formed in horizontal layers but those layers
were gently tipped over, millions of years later, by earth movements.
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