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Location and directions Directions: Blue Anchor is located just a stone throw from the neighbouring town of Minehead. Roadside parking is available along the A39, from which a vehicle slipway leads down to the beach. A short walk East leads to the fossil and gypsum bearing rocks.		Key information Geological period Triassic (Late) / Jurassic (Early) Approximate age 210 - 201 million years Fossil diversity Ammonites, marine reptile bones... Find frequency Low Dangers Risk of falling rocks Equipment Hammer, Chisel, Eye protection... Accessibility Easily accessible / rocky terrain Local facilities Good - shops and restaurants nearby Additional notes Site of Special Scientific Interest (SSSI)
How would Blue Anchor have looked 207 million years ago?

Introduction

Blue Anchor is perhaps the most unusual, alien environment we've ever encountered. The geology of the area includes two completely different rock types. At the far eastern end (beyond the view visible above) the rock is of early Jurassic origin, whereas the western end of the beach (as pictured) is the older Triassic, comprising the fossil bearing Rhaetian and the non-fossiliferous red Keuper Marl.

An illustration of the geological formations present at Blue Anchor - Note the Jurassic representation is
provided to demonstrate the approximate position of where the Lower Lias begins.

The point at which the two formations meet is known as the Blue Anchor Fault. The fault is a 'normal' fault - generated by extensional forces within the Earth's crust, causing the overhanging side of the fault (known as the 'hanging wall') to drop down. The result is relatively young rocks in the hanging wall resting against older rocks in the opposing 'footwall' side of the fault. In this case, the Penarth Group in the hanging wall has slide down the fault plane into contact with the older Mercia Mudstone. This activity took place during the Late Jurassic, some 50 million years after the rocks were deposited, and was probably a response to the same extensional regime which caused the opening of the Atlantic Ocean between the UK and America. This opening took place at the end of the Triassic, causing the sea to flood in from the south. The corresponding change from Triassic desert salt-pan conditions to Jurassic shallow tropical marine conditions is recorded in the rock succession at Blue Anchor.

Blue Anchor fault - Late-Triassic / Early Jurassic (Left) meets Red Triassic Keuper Marl (right).

Where to look for fossils?

You'll need to travel beyond the red Keuper Marl in order to reach the fossil bearing Triassic bone beds and Jurassic limestone beyond. 

Along the way you'll pass the most remarkable geology along the beach and at the peninsular.  At this point the Triassic rock is interlaced with bands of salmon-pink Gypsum crystals (a mineral form of Calcium Sulphate). These crystals appearance within the rock is striking, and make this area feel like a Martian landscape.

(Left) Examining the scale of a large cliff collapse. (Right) Gypsum crystals within a foreshore boulder.

Gypsum crystals from the backshore.

The abundance of these crystals means collecting fragments from the beach (backshore) is easy; however, so unique is this area, that visitors are discouraged from hammering into the boulders on the foreshore. In a single trip it would be easy to gather hundreds of crystals from the beach alone.

For more information about the features and processes controlling coastal fossil collecting locations click here.

What fossils might you find?

Fossils are most abundant within the Westbury Formation, located towards the top of the cliffs at the peninsular pictured above. The specimen below was collected from the backshore and clearly shows a near complete Plesiosaur humerous (see following diagram).

Plesiosaur humerous from the Westbury Formation, found on the backshore.

Plesiosaur skeleton diagram, indicating the position of the humerous.

As you move further east along the coast, fragments of the Lower Lias rocks can be found on the foreshore and backshore, these yield the best finds, in particular the Ammonite Psiloceras planorbis, which retain their mother-of-pearl-like shell.

(Left) Carefully exposing fragile ammonites within the Jurassic shale. (Right) Complete but fragile Ammonite Psiloceras planorbis

(Left) Small Ammonite Psiloceras planorbis. (Right) Large ammonite within the Jurassic limestone.

(Left) Hundreds of cavities caused by small bi-valve shells. (Right) Large bi-valve shells within the Jurassic limestone.

Protecting your finds

It's important to spend some time considering the best way to protect your finds onsite, in transit, on display and in storage. Prior to your visit, consider the equipment and accessories you're likely to need, as these will differ depending on the type of rock, terrain and prevailing weather conditions.

(Left) Fossil wrapped in newspaper, ready for transport. (Right) A small compartment box containing cotton wool is ideal for separating delicate specimens.

When you discover a fossil, examine the surrounding matrix (rock) and consider how best to remove the specimen without breaking it; patience and consideration are key. The aim of extraction is to remove the specimen with some of the matrix attached, as this will provide added protection during transit and future handling; sometimes breaks are unavoidable, but with care you should be able to extract most specimens intact. In the event of breakage, carefully gather all the pieces together, as in most cases repairs can be made at a later time...continued.

       

  

  

    

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Picture credits: White Tipped Reef Shark by Alistair Watters at travelblog.org; Plesiosaur by Doug Henderson; Seafloor from dragonja.nib.si. Safety notice: Fossil hunting can at times pose a risk to personal safety, in particular within environments close to the coast, cliffs or in quarries and when using the tools and equipment illustrated. Discovering Fossils provides a free resource to inform you about this fascinating subject and does not accept any liability for decisions made using this information. We recommend all individuals abide by the 'National Fossil Hunting Code' and independently research the potential dangers before and during the visit.

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Written and designed by Roy Shepherd