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The rocks of
Hartland Quay are the remains of a mountain range.
Sedimentary rocks were deposited in a shallow sea during the
Carboniferous period – about 320 million years ago. The layers
are sequences of shales and mudstones representing the remains
of sub-marine “avalanches” of sediments called turbidites.
At the same time as the sands and mudstones were being deposited
at Hartland, coals were being deposited in swamps, forming the
South Wales coalfields.
Plate tectonics caused the collision of two super continents
with Hartland Quay in the middle. Devon was at the
southern margin of a super-continent called Laurasia,
which collided with the super-continent Pangaea – to the
South. As these two mega-continents collided during the
Variscan
Orogeny the rocks at Hartland Quay were buckled and
folded, producing the spectacular chevron shaped folds
exposed in the cliffs today. The top surface was then eroded
flat.
The cliffs at
Hartland Quay inspire both non-specialists and the professional
geologist; and little or no geological knowledge is required to
appreciate the hundreds of millions of years of natural history.
Simon Jones, Exploration Geologist, First Quantum
Minerals, Ndola, Zambia Africa |