As you enter the entrance at Paddington Station, follow the signs for Platform 12 and 14. Before you reach the platform and indeed the barriers, you will notice a nationally recognised coffee take-away shop (the blue one) and a white pillar with a red fire alarm. You should see a Platform 12 sign above your head. Pause a while and take a look at the floor. Here, you should see a rather large and impressive fossil. It might remind you of car tyre markings on a dirt track road. If you want further help to locate the fossil, use the photos in the gallery. There'll be 2 photos in green boxes and the fossil is obscured by a yellow square.
Questions
This is a high difficulty EarthCache due to the slightly jumpy coordinates, but the detailed directions should lead you to the desrired fossils. Detailed answers would be beneficial to explain what you see here to earn the D rating.
1) Give accurate measurements of the fossil, to the nearest centimetre (or inches if you prefer), in terms of length and width.
2) Have a look at the shapes and patterns on the ammonite. Describe the lobes and saddles. Explain the size, shape and colours of what you can see.
3) You can also spot other part(s) of the ammonites’ anatomy. Tell me what you can see and why this is evident here. This is the hardest question, but the images of ammonites on the cache page will certainly help you. Perhaps everything that should be there is not what it seems?
4) Feel free to take a photo of yourself (or something personal to you, your GPSr, a TB or caching name on a piece of paper) during your visit to Paddington Station. This is an optional requirement. PLEASE DO NOT INCLUDE PHOTOS OF THE FOSSIL IN YOUR LOG.
The fossil in Paddington Station
Below your feet, you should be able to see a rather impressive ammonite and a few other, much smaller, fossils dotted around. But there isn’t an ammonite, you say! Yes there is – you’re not looking at it in the right context! When the floor tiles were cut at the quarry and later shaped into the floor tiles you see here, the angle the limestone was cut means that you are seeing it from above, not from its side, So, you’re looking at the keel, it’s long thin edge, rather than it’s spiralled side. Hopefully these images will help you understand how you’re looking at the ammonite, as if you were looking at it from a side angle.
The left image below shows the ammonite spiralling downwards below the surface and you would only see the keel. The image on the right, resembles a cross-section if you were standing on an ammonite that you would usually be accustomed with when researching many other ammonite-related EarthCaches. The images are not to scale.
History
In 1990, a scientist, Dr Birger Schmitz, from the Earth Science Centre in Gothenburg, read some newspaper reports saying that an amateur geologist named Mario Tassinari had found a few fossil meteorites in the Thorsberg Quarry on the southern shore of Lake Vänern, Sweden. At this time, there were only a handful of fossil meteorites known to science. Was this a chance to study what meteorites had been like millions of years ago and piece together the effects they had on Earth? Dr Schmitz contacted Tassinari and they agreed to collaborate on a systematic study of the quarry.
The quarry workers carve out sheets of limestone for modern uses such as floor tiles and paving slabs. When they find a piece that looks like it might hold a space rock, they call Dr Schmitz. Each year, they get four or five fossil meteorites. He has also spent time hunting for meteorites in places with the floor tiles from the quarry that have been utilised, such as here in Paddington Station. But it turns out Thorsberg Quarry is, as far as we know, a one-off. Special conditions are required to preserve sizeable fossil meteorites in reasonable numbers. After some thorough investigation, it is estimated that these meteors are 470 million years old. Now we know the material and it’s age, it makes things easier to identify these fossils, the material stone and also their age. For citation and further information, please click here.
Climate Change and Sea Levels
During the late Silurian period and early Ordovician period, the sea levels were constantly changing, due to many volcanic eruptions and extremely high carbon dioxide levels. This resulted in the fauna to increase at a vast rate (due to the amount of photosynthesis taking place in the flora and thus plenty of food along the short food chain). As the tectonic plates were also changing dramatically, marine animals were often dispersed in places that would often not be considered to be an area typically associated with marine wildlife today, such as Central Africa or the South Pole. The seas in the northern hemisphere were largely covered with shallow seas, with clear water encouraged the rapid growth of organisms that deposit calcium carbonates in their shells and hard parts.
The fauna was dominated by tiered communities of suspension feeders, mainly with short food chains. The ecological system reached a new grade of complexity far beyond that of the Cambrian fauna, which has persisted until the present day. During the Ordovician radiation (also known as the Great Ordovician Bio-diversification Event), marine fauna generally increased fourfold, resulting in 12% of all known marine fauna. Several animals also went through a miniaturisation process, becoming much smaller in the Cambrian period.
Some Ammonite Terminology
An Ammonoid characteristically have bulges and indentations and are to varying indentations. Scientifically, these are called saddles and lobes. Saddles curve out, whilst lobes curve inwards. Think of it like peaks and troughs.
Internally there are several parts of an ammonite, as shown in the diagram below. Ammonites begin bery small, and as they grow, an extra chamber is formed to allow room for extra movement, comfort and growth. The chambers contain gases to allow buoyancy. The septas are the parts that separate each chamber and the siphuncle is the part that runs along the centre of the outer shell into the centre. Looking at the image above, you should see the siphuncle running from top to bottom in the centre. It is also known as a keel to some scientists.
