Geology
Geology determined the foundation of Pembroke: it is situated on a ridge of hard Carboniferous limestone Coloured light grey on map) surrounded by the older but softer Devonian shales and sandstones (coloured orange and pale pink).
The historic core of Pembroke is constructed on this low, east-west aligned, limestone ridge, to the north and west of which lies the tidal (but now dammed) Pembroke River and to the south an area of marshy land (now partly reclaimed and under car parks) called the Commons. Pembroke Castle, on the western end of this ridge, dominates the whole of the town that developed in stages eastwards from the castle, along one long main street.
The town is situated at the head of one of the many creeks of the Milford Haven waterway, a drowned river valley known as a ria and now designated an SSSI and a Marine Special Area of Conservation.
The hard nature of the limestone provided the prominent outcrop for the construction of the castle, also, because limestone is soluble in water, the presence of caves enabled early man to settle here.
LIFE BEGINS
In the carboniferous seas 350 million years ago there was abundant life when this area lay beneath a tropical sea.
Fossil evidence can be found in the lower limestone shales _ crinoids (coral like plants) and brachiopods (shell fish)
Take a look at Pembroke's nearby coastline at Stackpole Quay where you will see ample evidence of these early life forms in the numeous fossils in the limestone cliffs.
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Crinoids Brachiopods
LEARNING ABOUT GEOLOGY
Pembroke Story and the Millponds Group volunteers combined to learn more about Geology with Sid Howells, our local expert geologist. Here we are assembled on Freshwater East beach on a lovely summer's evening.
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Following on from this we met on the cliffs above Skrinkle and Church Doors.
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Photos by Linda Asman
The Geology of the Castlemartin Peninsula
Pembroke is situated at the head of the Castlemartin Peninsula - here old red sandstone and carboniferous limestone rocks combine to form some of the finest cliff scenery in Britain.
Take a walk around the coastline to see for yourself. Beginning at Freshwater East you may find the undulating path rather taxing: here old red sandstone cliffs form a landscape that is contorted and crumbling with steep ups and downs.
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Approaching Stackpole Quay the beautiful red rocks give way to the grey carboniferous limestone.
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From here, sheer and dramatic cliffs with flat, grassy plateaux make for much more easier walking.
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Particularly spectacular are the cliffs at Stack Rocks to Linney Head which are unfortunately barred to the public for most of the time due to the MOD Artillary Range - accompanied walks are arranged with the National Parks.
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There are beauful sandy beaches along the way at Freshater East, Broadhaven, Barafundle and Freshwater West.
From here the old redsandstone reappears to form a cliff path that is again rather more challenging and brings us to West Angle Bay.
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Here we enter Milford Haven where we encounter modern industry in the shape of jetties and oil refineries.
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Once past Angle the scenery changes as we leave the coast to walk up the Haven and the Pembroke River.
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And here at Quoits Mill we have to leave our walk as we can walk no further up the Pembroke River and have to approach Pembroke through Monkton.
Photography by Linda Asman.
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