Fossils!!!

What we think of is T Rex, and the big fossils of museums. But on the path up to the Cow and Calf there is  spectacular fossil, that most just walk past. 

This is not meant to be difficult, and is ideal for those with children, or limited mobility that prevents a trip up onto the moor, where there are more fossils to be seen.

As you walk up the flagstone path to the cow and calf you will notice a large boulder. Oh, well you may think, another stone, there are lots of them around here.

Look at the side which borders the path, there is a tube like feature, this is the fossil.It is a plant fossil. A type of tree from the Carboniferous period known as a Lepidodendron​ tree.

What is a fossil?

Fossils are  the preserved remains or traces  of animals, plants, and other organisms from the remote past. The process of fossilization varies according to tissue type and external conditions.

(1) Permineralization

This occurs when an organism is buried. The empty spaces within an organism (spaces filled with liquid or gas during life) become filled with mineral-rich groundwater. Minerals fill the empty spaces. Small scale permineralization can produce very detailed fossils. For permineralization to occur, the organism must become covered by sediment soon after death or soon after the initial decay process. The degree to which the remains are decayed when covered determines the later details of the fossil. Some fossils consist only of skeletal remains or teeth; other fossils contain traces of skin, feathers or even soft tissues. 

(2) Casts and Molds

In some cases the original remains of the organism completely dissolve or are otherwise destroyed. The remaining organism-shaped hole in the rock is called an external mold. If this hole is later filled with other minerals, it is a cast.

(3) Authigenic mineralisation

This is a special form of cast and mold formation. If the chemistry is right, the organism (or fragment of organism) can act as a nucleus for the precipitation of minerals around the fossil  resulting in a nodule forming around it. If this happens rapidly before significant decay to the organic tissue, very fine three-dimensional morphological detail can be preserved.

(4) Replacement and recrystallization

Replacement occurs when the shell, bone or other tissue is replaced with another mineral. In some cases mineral replacement of the original shell occurs so gradually and at such fine scales that microstructural features are preserved despite the total loss of original material. A shell is said to be recrystallized when the original skeletal compounds are still present but in a different crystal form.

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. It is not meant to be difficult to do.

​1. Please tell me how wide the tube is?

​2. Please look at the inner aspect of the tube, what can you see and feel?

​3. What process of fossilization has occured here?