|
|||||||||||||||||||||||||||||||||||||||||||||||||||
Introduction
Dunrobin is better known for its fairy-tail style castle 'Dunrobin Castle' than its fossils, which in comparison are small in size and number; however experienced visitors should be able to locate a range of specimens from the Jurassic rocks accumulated at the base of the low-cliff. In comparison with other locations that yield Jurassic fossils, the find frequency at Dunrobin is very low and is therefore not recommended for collecting.
(Left) Parking is available in the main car park of Dunrobin Castle. (Right) Access to the beach is made via the southern side (right) of the castle.
Parking is available in the castle car park throughout the year (above-left), from which a path descends to the foreshore via the south-side of the castle (above-right).
The geology of the foreshore near Dunrobin Castle
The geology of the coast beneath Dunrobin Castle represents a transition during the Lower Jurassic (200 million years ago) from freshwater sediments, through estuarine deposits (with occasional marine influences) to fully marine. Evidence of this changing environment is clearly apparent from the change of fossils fauna within the foreshore exposures and the low-cliff.
(Left) Underlying marginal marine sediments - 'White Sandstone Unit'. (Right) Marine sediments - 'Lady's Walk Shale Member'.
The following page is concerned with the exposures within the low-cliff (above-right), which specifically relates to a period of marine conditions during the early part of the Sinemurian stage (Lady's Walk Shale Member). The transition from the underlying 'White Sandstone Unit' (semi-marine) can be clearly followed moving north-east.
Where to look for fossils?
Fossils can found within intermittent exposures on the foreshore and within the eroded low-cliff (below-right); a low-tide is needed in order to observe foreshore exposures. During our recent visit the only exposures were at the top of the beach, within the low-cliff (Lady's Walk Shale Member), and it's here that the following page is based upon.
(Left) View towards Dunrobin Castle from the beach. (Right) Sinemurian marine sediments - Lady's Walk Shale Member, exposed by coastal erosion.
Once on the beach, walk in north-east direction along the foreshore, passing in front of the magnificent castle (above-left), past the sea defenses (paved foreshore) and onwards towards the eroded shoreline (above-right).
For much of the year the high-tide doesn't reach the top of the pebbled beach and as such it's usually possible to find fossils. Please note that this stretch of coast has been assigned SSSI, which means extracting fossils directly from the exposures is not permitted; however collecting is allowed from the loose material accumulated at the base of the eroded shoreline.
For more information about the features and processes controlling coastal fossil collecting locations click here.
What fossils might you find?
It takes quite some time to gather enough specimens to begin to build a picture of what life was like in this region 200 million years ago; with patience Bivalves, Brachiopods, Belemnites and Ammonites (reported but not observed during our recent visit) can be found.
The following specimens were collected from the 'Lady's Walk Shale Member' (see notes above).
(Left) A small bivalve. (Right) The inner-side of a small Brachiopod shell.
(Left) A fragment of crinoid stem - Balanocrinus sp. (Right) The inner cast of a small Brachiopod shell.
The
crinoid fragment (above-left) has been identified by the Hunterian Museum
as a significant find for Dunrobin, and a paper to describe it is planned
for the near future. Please report any crinoid finds in this area to
Dr Neil Clark at the Hunterian Museum of Glasgow or alternatively
(Left) The broken tip of a small Belemnite protruding from the eroded coastline. (Right) A small bivalve.
(Left) A partly squashed Brachiopod. (Right) A small Brachiopod from the 'White Sandstone Unit'.
The final photo (above-right) is included to represent the underlying 'White Sandstone Unit'; the sandy sediment represents a marine-marginal facies.
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.
|
|||||||||||||||||||||||||||||||||||||||||||||||||||
