Often walked up and down this shopping but never realised what I was walking on... HISTORY!
You are currently on top of Limestone that came all the way from Germany.
Sedimentary rocks are made up of the weathered fragments of other rocks, or the remains of plants or animals.
This Limestone is formed from the remains of many animals, both large and small.
Limestone is mostly formed from calcite. Calcite is a form of Calcium Carbonate, which has the chemical formula CaCO3. Calcium Carbonate is the same material that produces the ‘fur’ on the inside of a kettle.
Calcium Carbonate is removed from seawater by the animals as they grow. When the animals die, their skeletons accumulate on the sea floor and are later turned to rock by a process known as lithification.
The majority of the fossils in this limestone are crinoids. Crinoids were animals related to starfish and sea urchins with a long stem. The long fossil towards the top of the image is part of one of these stems. The round ‘polo mint’ like fossils are parts of crinoid stems that have fallen apart into their individual elements.
If you look closely, you can see several fossils in the stone itself. These are Belemnites and Ammonites.
Belemnites (Belemnitida) were squid-like animals belonging to the cephalopod class of the mollusc phylum, and therefore related to the ammonites of old as well as to the modern squids, octopuses and nautiluses.
Now extinct, their fossils are found in rocks of Jurassic and Cretaceous ages, with a few species hanging on into the early part of the Tertiary. The animal’s soft parts very rarely fossilise, leaving us with only the hard parts; the guard and the phragmacone.
Ammonites (Ammonitida) were shelled cephalopod molluscs that lived throughout the world’s oceans during the Mesozoic (Triassic, Jurassic and Cretaceous periods). They were an extremely successful order, as evidenced by the frequency that their remains are found.
Limestone is an important rock type. It is widespread and often contains beautifully preserved fossils, but is also economically important. Limestone has been used as a fertilizer for heavy clay soils, as a flux for iron and steel making, and for making cement and concrete.
Limestone is an important building stone, but it is slowly dissolved away by acid rain.
Rainwater is naturally acidic as it contains small amounts of carbon dioxide from the air, forming carbonic acid. In polluted areas rain becomes even more acidic and causes damage to limestone buildings and statues.
Weathering of naturally occurring limestone leads to limestone pavements or a ‘karstic’ landscape.
In order to claim this Earthcache please answer:
1 - What is stratigraphy? Ammonites (and other marker fossils) are important to the study of stratigraphy around the world. Can you think of a reason why this might be the case?
2 - Look at the bigger fossils visible in this stone. Describe them in terms of size and shape. What sort of fossil is it?
3 - Count the closest row to the exit of limestone (the thinner one). How many slabs form it?
Please do not share your answers in your log. E-mail them to me, but feel free to log immediately. Incorrect answers or logs without answers being sent will be deleted.
Information taken from the following pages:
http://www.thinktank.ac/page.asp?section=493
http://www.ukfossils.co.uk/guides/belemnites.htm
http://www.ukfossils.co.uk/guides/ammonites.html
Placed with the kind permission of Intu Uxbridge.
Thank you to the reviewer geoawareUK2 for the guidance and support.