This EarthCache takes you to the centre of Settle. The location of the area where you need to look, is indicated in the below photographs.
🤔 What are we here to look at?
Well, we are here to look at some of the paving slabs. The paving slabs are made from sandstone, which is a sedimentary rock. It is a sandstone laid down during the Carboniferous period. Sandstone is a sedimentary rock. During this time the north of England was covered by a vast river delta, down which was carried and deposited immense amounts of sediment in the form of sand, pebbles and rocks. Here at this site there is evidence of a different geological process. Imagine the Amazon river delta, an area of trees, various plants and animals.
During the Carboniferous Period, conditions changed at times, and as a result various rocks were laid down. These are known as sedimentary rocks, as sediment which was carried by the river delta was deposited in layers. Now, it might have been pebbles and sand which when deposited and then compacted over time, then formed sandstone. Sandstone, tends to be light yellowy / brown in colour, and can be rough or smooth to touch. At times, smaller fragments known as sediment was laid down, and this formed siltstones and mudstones. These tend to be very dark brown or black in colour, and have very thin layers.
Now, during the process of sediment being deposited, also parts of plants or animals were also deposited, over time these became part of the rock and formed fossils. These might look like shells, pieces of wood, branches or bark.
🤔 Fossilisation.
Fossils are the trace of an animal, plant or activity by an organism. These have become part of the rock structure, hence why are found in rock. There are different ways that they form.
🟫 Burial.
A dead animal, piece of wood or plant can become quickly covered in sediment, over time this sediment increases, fills the void left by the decomposing organism, compaction occurs and basically a trace remains which becomes part of the surrounding rock. At times the void left by the decomposed animal can be filled by Calcite.
An example, fossil brachiopods, Littondale.
🟫 Replacement and permineralisation .
When an organism dies, and it is buried by sediment, which then compacts over time into rock, a process called replacement and permineralisation can occur. Basically during the process of compaction of sediment, there can be immense pressures at force, this along seepage of water through the rock, can transform any remains into the rock, so the fossil actually becomes part of the rock, such as calcium carbonate with limestone.
An example of an fossil tree bark, Bentham.
This being an EarthCache, in order to log it, I ask that you answer some questions. Please send them to me, and do not include them in your log. You can send them to me by using the message facility or email, both of which can be found by looking at my profile.
1. Please describe the fossil, in terms of length and appearance.
2. Please explain what type of fossilization has occured here.