My wife and I have spent many happy days collecting fossils on the Yorkshire Coast between Staithes (NZ783189) in the North and Scarborough (TA041893) in the South. As a result of our collecting I have put together this page to help people who find fossils in this area to understand what they are and what they once were.
The rocks in this area cover a period from Lower Jurassic (approx 190 million years old) to Middle Jurassic (approx 150 million years old). The older rocks are generally towards the North of this area and the younger rocks to the South. During this time period Britain was much closer to the equator and in the Lower Jurassic the Yorkshire Coast was under the surface of a warm tropical sea. As time progressed, as the result of earth movements, the sea became shallower and about 160 million years ago the area was more like a river delta with swamps and lagoons. Some of the inhabitants of this area during this time have been preserved as the fossils we find on the beach and in the cliffs.
What is a fossil?
In its simplest form - something dies, usually in water - it slowly gets covered with sand, mud or silt as the soft parts decompose and leave a cavity - over millions of years the cavity becomes filled with mineral substances which form a cast of the original creature or plant and, because of the great pressure of the overlying covering, the cast usually becomes deformed.
There are a great number of variations to this theme, the creature or plant may die on land and be covered by sand from a high tide, it may be washed into a river or it may be covered over by volcanic dust. In some cases the whole thing will not decompose and the fossil will still contain some of the original item, for example shells, resins, oils and carbonised remains.
Yorkshire Coast Fossils
Scale - The black squares in each picture are 1cm.
each.
The figures in brackets are UK Ordnance Survey Map References.
Ammonites
In the Whitby (NZ900103) area ammonites are generally
preserved in three ways, they will either be found squashed very flat on the
surface of shale(1), preserved more or less intact inside an ironstone nodule
(2) or preserved in mudstone, usually with the outer whorl intact but the centre
squashed (3).
Local legend says that the ammonites were formed when the Abbess
of A WORD OF WARNING
- although
collecting fossils from the shale and mudstone is reasonably safe, take great
care if you are trying to break open the ironstone nodules with a hammer, very
sharp flakes of ironstone will shoot off at all angles and may blind you if you
are hit in the eye. Also please beware of rocks falling from the unstable cliffs
and watch the tides (it is very easy to get cut off in some places).
The local name for these fossils is 'Devils Thunderbolts' and they do resemble
bullets. The nearest modern equivalent for the part most commonly found is a cuttlefish
bone (often found in Budgie's cages). Belemnites vary in size and shape,
unusual long thin ones (Cuspiteuthis
tubularis) can be found
on the surface of the shale near to Black Nab in Saltwick Bay (NZ922108).
The best place to look for dinosaur footprints is
Burniston Bay near Scarborough (TA027935). Follow the steps down to the beach
and then turn left, the large sandstone blocks at the base of the small cliff
sometimes have three toed footprints on the surface. The footprint bed is the
layer of sandstone about 3-4 metres up the cliff face from which these blocks
have fallen. Although Burniston Bay is the easiest place to find the footprints,
they can be found all along the coast from Scarborough to Whitby. The one in the
picture was found at Saltwick Bay (NZ915109).
The Ginkgo
leaves (left) are from
the 'Scalby Plant Beds'
at Scalby Ness
(TA037912) just North of
Scarborough. The Ptilophyllum (right) from the
'Whitby Plant Beds' (NZ910114) South of Whitby. The well preserved section of
tree trunk (below) was found on the beach at Robin Hood's Bay (NZ954054).
The two smaller vertebrae pictured on the right are from
Saltwick Bay and the single larger vertebra on the left was found on the beach
between Saltwick bay and Whitby, unfortunately it is broken in half and the
other part could not be found.
When shellfish died most of the shells became filled with
mud or silt, this provided a solid 'core' for the shell as it became fossilised.
As the shell was made of a substance similar to the fossilising minerals quite
often parts of the shell remain intact and the original colours are visible.
The shell pictured to
the right is called Dacryomya
ovum (formerly Nuculana ovum) and is very
common around Whitby (NZ904115), beds of hundreds of the fossilised shells can
be found in the cliff face and large numbers loose on the seashore.
Scaphopods are shellfish which first put in an appearance in Devonian times
(417 to 354 Million Years Ago) and have hardly changed since. They can still be
found in warmer climates and are known as 'tusk shells' because of their
similarity in appearance to elephant's tusks. It can be fun collecting fossils but the area between
Staithes and Scarborough can also be very dangerous. The cliffs are constantly
losing pieces from small flakes of shale to massive boulders of sandstone and
they fall downwards.It is a good idea to look up occasionally and see how near
to the cliffs you are. If one of the larger pieces falls on your head you are
DEAD! Most of our fossils and all of the 'best' ones (including the Dino
Footprint) came from amongst the shingle, shale and rocks well away from the
cliffs and did not have to be hammered out. Hammering and chiselling the cliff
face can cause cliff falls and after a lot of effort you will most likely end up
with a broken part of a fossil. Looking carefully around on the ground will most
likely produce a lot better (possibly undamaged) specimen without the risk to
life and limb.
Beware of the tides, some areas can get cut off up to 3
hours before high tide. Always check the tide tables and if you are new to the area then talk
to the locals. Robin Hoods Bay can be particularly frightening, the shore is
flatt(ish) and the tide suddenly starts to come in very fast. Once you are
trapped by the tide climbing the cliffs is not an option. At best you may have
to wait up to 6 hours for the tide to go down, at worst you will DROWN.
If you must hammer then ALWAYS wear protective goggles
and particulary if you try to break open a ironstone nodule.When hammering or
chiselling there is a good chance that thin sharp slivers of rock will break off
and fly in all directions, please wear eye protection. I know they can be
cumbersome and some people may think it is 'soft' to wear them but, I would
sooner be 'soft' than BLIND.
OK... enough. If I haven't put you off collecting fossils in this
area then please click on
these links to take you to
Mike Horne's excellent notes
on GEOLOGICAL
FIELDWORK
and
COLLECTION
AND CURATION OF
GEOLOGICAL MATERIALS.
They will tell you how collecting is done by the experts and how it should be
done by everybody.
Any
questions, comments,
corrections, requests
for enlargements of
photos etc. please use
the E-Mail address on my
home page.
The most popular fossil from the Yorkshire Coast is the ammonite. Resembling a coiled snake, called 'snakestones' locally ammonites can be found along the whole length of coast from
Staithes to Scarborough. When alive an ammonite
resembled the modern day pearly nautilus, rather like a squid in a shell. The
creature only lived in approximately a third of the outer portion of the shell,
the rest of the shell being made up of gas filled chambers that acted as
bouyancy aids to enable the ammonite to swim without sinking.
1
2
3
Whitby (later St. Hilda), drove a plague of snakes over the cliff at Whitby. The species of ammonite pictured on
the right was named Hildoceras in honour of this mythical feat.
Belemnites
As with ammonites, the belemnite was a squid like creature but instead of having the ammonite's external
shell the hard structure of a belemnite was on the inside. This internal shell is known
as the guard.
Phragmocones. The extension to the guard in a belemnite is known as the phragmocone. As the phragmocone was more delicate
than the guard they are more difficult to find as they are unlikely to have been
preserved intact. Occasionally they will be preserved inside an ironstone nodule
and more rarely in shale. The guard with phragmocone attached in the picture
below was found at Whitby (NZ905114) and the nodule is from Saltwick Bay (NZ915109).
Dinosaur
Footprints
Although not a true fossil and described as a 'trace fossil', it can be very
exciting to find evidence that dinosaurs once roamed this area. Approximately
160 million years ago when the area around Whitby was a huge river delta there
were large mudflats which were roamed by dinosaurs. Dinosaurs walking in the mud
of course left footprints. Some of the mud, with footprints, dried very hard in
the tropical heat. As the result of a flash flood or very high tide some of the
footprints became covered by sand. The sand and mud layer became further buried
by more layers of sand, silt and mud and over time changed into sandstone and
mudstone. The footprints we find nowadays are actually 3D sandstone casts of the
original footprint.
Plant Remains
Plant remains are quite common in the Whitby
and Scarborough areas. Leaves are usually preserved as carbon impressions of the
original leaf. Tree trunks and branches are sometimes preserved as flattened
coal like bands, sometimes as mineralised casts and occasionally as Jet.
Click here to visit my Jet pages
Marine Reptiles
During the
Jurassic period the seas in this part of the world were the home of ichthyosaurs
and plesiosaurs. Both measured from 3 to 13 metres in length. The ichthyosaur
resembled a dolphin in appearance and is thought to have been a fast and
powerful swimmer. The ichthyosaur was the only marine reptile known to give
birth to live young. The plesiosaur had a very long neck and used four paddle
like fins for propulsion. In contrast to the ichthyosaur, the plesiosaur would
leave the water to lay eggs on the land. It is thought that if the Loch Ness
Monster exists it is probably a descendent of the plesiosaur. Both reptiles were
air breathers and would have to surface regularly for air.
Although
fossilised remains of reptiles are uncommon they can be found in this area.
Vertebrae are the most common parts to be found, usually on the seashore, and
look like discs with concave sides ranging from 1cm to 30cm in diameter.
Complete skeletons are still occasionally found in the cliffs but are extremely
difficult to remove intact.
Bivalves
Cockles,
mussels and oysters are all bivalves. The only difference is that some of the
shellfish you find on the Yorkshire Coast are 150 to 190 million years old (not
the ones on the seafood stalls).
Crinoids
Amongst the shingle on the beach you may
find very small fossils which resemble starfish. These are not starfish, they
are part of a crinoid, a creature which is related to the starfish. A crinoid
can be described as rather like a starfish on a stem. The stem would be made up
of hundreds of these flat star shaped plates, called ossicles, stacked one on
top of the other. At the top of the stem would be the head (calyx) with 5 or
more arms which were used to catch food and at the bottom of the stem a 'root'
system to hold the creature down. Although crinoids look like plants and have
the nickname 'sea lillies' they are not plants.
Pictured
on the right is what we
think is a badly damaged
calyx and arms
assemblage of a Pentacrinites
fossilis crinoid.This was found in Robin
Hood's Bay.
Scaphopods
In life a scaphopod lives buried in sand with just the thin
end of the shell protruding into the water and the head end (called the foot) at
the lower end. The picture on the right shows a scaphopod in life
position.
The scaphopod pictured above, Dentalium Giganteum, was found in a loose block of
siltstone at Robin Hoods Bay (NZ958059) although they are much more common on
the east side of Staithes Harbour (NZ788190) where they can be seen as clusters
of white lines on the surface of the rock platform.
Collecting
That's
it for now. If we find
anything else interesting
or you suggest anything we
can add to this page we
will update it as
necessary.
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