WEBVTT

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We're walking up towards

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the famous Gin Cave here at Blackhall.

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and we're going to try

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to see if we can pick out
some of the different features

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that make up the different Permian
limestone formations.

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Now there are formations that have been
mapped here at Blackhall Rocks.

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The Ford Formation, the Roker

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Formation and the Seaham Formation.

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And they're all made of

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carbonates.

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They're all made of limestone,
and they're not necessarily

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that easy to pick apart and distinguish
as you walk along the cliff.

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So one of the things
that slightly complicates

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the stratigraphy here at Blackhall
is faulting.

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So rather than a simple layer
cake stratigraphy.

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where we find the oldest
rocks at the bottom

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and the youngest rocks at the top,
the faulting has offset

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the vertical distribution
of some of our formations.

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So, for example.
just to the south of the Gin Cave,

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we find the Seaham Formation
low down in the cliffs.

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When really stratagraphically
it should be at the top.

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So the Ford the Roker and the Seaham

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are not necessarily
in stratigraphic order.

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but we're going to try to see
if we can pick out some of the different

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elements of them
as we walk along the cliff.

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Now, some of those formations
were deposited in deeper water.

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some of them along the reef rampart
and some of them

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in the intertidal lagoon behind the reef.

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So different processes.
are driving the formation

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of different features.
which we'll see here in the cliffs.

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Immediately in front of us,

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just to the south of the Gin Cave,
at the base of the cliff,

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we have the Ford Formation and the boulder
conglomerate, which forms it.

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And just above it
we have the Roker Formation

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with the famous crinkly beds
and the stromatolites.

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And we're going to have a look
to see if we can find them.