A nice example of a commonly found ammonite
On Saturday 1st October 2011, a young fossil hunter on our walk found a nodule. Our geologist split it for him with a single blow of his hammer and the picture below shows the result – no fossil preparation required!
The fossil is Promicroceras sp. This is probably the most commonly found ammonite on Lyme Regis’s beaches. It is small; the one found was actually a very large specimen. When a nodule breaks like this, the fossil is said to have “popped. What actually hapens is that the fossil splits along the join between the ammonite’s shell and the calcite crystals that have filled its hollow chambers. The shell is on the imprint, stuck to the rock because of its roughnes. The smooth inner surface of the shell easily splits away from the calcite to produce a beautiful crystal ammonite.
For more information, see Fossils as Living Creatures.
Girls with backbone
Maya and Holly went on one of the Museum’s fossil walks recently and found a very unusual specimen: a short section of fin spine from a fish called Myriacanthus paradoxus. Well that sounds really interesting but we don’t have a picture of the fossil – so if Maya or Holly are looking in then please send us a photograph and we’ll put it on the web-site.
However, the next day, using their fossil detective training to the full, Maya and Holly went out by themselves on the beach. This time they found a line of ichthyosaur vertebrae in the shingle infront of Church Cliff. They said that they had recognised it because of the information they had learned and specimens they saw during the walk the day before. The vertebrae are still articulated and have their neural arches attached. They come from towards the end of the animals tail. The backbone of an ichthyosaur bent down into the bottom of its tail and this line of vertebrae that the girls found is the section where it bent. You can see the vertebrae rapidly decreasing in size towards the end of the tail. The vertebrae probably come from the shales with beef and are about 200 million years old.
Back at the Fossil Workshop, the vertebrae were cleaned up to make a very nice souvenir for the girls to take home.
The smile makes it so worthwhile
On our Fossil Walk on 16th August 2011, Paddy Howe opened a nodule for a young girl call Amelia and found a lovely specimen of an Arnioceras ammonite. This was cleaned up back at the Fossil Workshop and turned out very well. Amelia’s smile was worth the effort.
Young fossil hunter finds a goldstone nodule
Jack, age 6, found a goldstone nodule on our Fossil Walk on 31st July 2011. Museum Geologist,Paddy howe split it open for him and Jack was very pleased with the result.
On the18th July 2011 a participant on one of our fossil walks found a piece of “beef” on the beach infront of Church Cliff. “Beef” is the Victorian quarrymens name for the fibrous calcite layers you find above the alternating limesones and shales of the Blue Lias. The early geologists bought fossils from the quarrymen and so started using their names for the rock layers. Any modern geology book on Lyme Regis will mention the “Shales with beef”. Beef is notorius for looking like fossils, on fossil walks we get handed pieces of beef every day, at best they contain squashed ammonites or shells. This particular piece was different. It contained two complete ichthyosaur vertebrae and two partial ones. It was clearly an articulated length of ichthyosaur backone. What made it especially interesting was an almost identical piece was found in the same place a few weeks earlier. These are undoubtedly from the same animal and do actually fit together, although the joint is not very snug as both sections are worn.
In the photophraph the most recent section is on the right, it is slightly darker as it is still damp from being cleaned. Neither section is fully prepared, but it is valuable to have a picture of both together before they go to the separate homes of their finders. It is not unusual as people may think for parts of a single animal to be found by different collectors several weeks apart. Sometimes parts of an animal are collected over a period of years.
The weather in Lyme Regis has recently has been poor for collecting fossils, far too nice and sunny, but despite this there are still some good finds on walks. On the same day that the second backbone section was found we also had five more individual vertebrae found. All were small and some a bit worn, but it shows that despite the poor weather there are still interesting things to find if you look hard enough!
A lucky slip of the hammer
At the end of the Museum’s fossil walk on 21st May 2011, Museum Geologist, Paddy Howe split a rock for Vincent Wong, a vistor from Hong Kong. This exposed a small example of the most common ammonite found in Lyme Regis, Promicroceras (see right), of which most specimens are 1.5-2cm across and a crushed specimen of a larger ammonite called Asteroceras. As he was leaving Lyme early next morning, Mr Wong went to the workshop after the walk to have his ammonite cleaned. For a small ammonite close to the surface of the rock this normally takes just a few minutes. The fossil was cleaned (see below), but the rock needed to be made smaller due to weight restrictions on the filght home.
Paddy split the rock but it broke in a different way to that expected and revealed a second Asteroceras ammonite in the middle of the rock! This took about an hour to clean, but the result was well worth the effort (see below).
American tourist strikes gold
Leigh Goddeau from Florida found a ‘goldstone nodule’ during our Fossil Walk on May 7th 2011, these are not common but often contain nicely preserved Arnioceras ammonites which, happily, proved to be the case this time. Leigh was obviously very pleased with her find.
After the walk, the Museum’s geologists cleaned up the specimen for her to take back to the USA.
Here is a poem written by a visitor to the museum who has now become addicted to collecting fossils to such an extent that she would like to move to the area.
Searching, looking through the sand
Seeing what treasures cone to hand.
The mysteries of the past still there,
Some of them hidden, some of them bare.
Walk up the beach with head held down,
searching for riches, which when found,
Offer a peek to another world,
Locked up in rock until they’re furled.
With chisel in hand and hammer in other,
We seek to wake what lies in slumber.
Wonderful creatures hidden from sight,
And finally now, they see the light.
It’s hard to believe that they lived here,
so very far, but yet so near,
Under our feet their bodies lie,
Waiting for us, as we walk by.
We’ll show them off, we’ll sell them on,
As fossils now they won’t be gone.
They tell a story of life unknown,
They’re not just rock, shell or bone.
Louise Kent 20th December 2011