The Kinnear Question 🤔 EarthCache

Whilst walking around Keswick recently, I was accompanied by a visitor from Scotland.  He stopped and pointed to a feature in a building, and asked....what is this?

This led to the development of this EarthCache, and a journey of development and enrichment.  

The below photograph shows where to look.

The geology of the area is very old, Ordovician rocks make up Skiddaw which towers above the town. These are 500 millions of years old, indeed the bulk of the stone which makes up this building is from this geology, but the area we are interested in, is of a different type of stone. It is sandstone, which is a sedimentary rock, formed from the accumulation of sand grains in layers. We are here to look at a feature in the sandstone which prompted the Kinnear Question 🤔. 

You will notice an almost artistic feature in stone. It is however natural. So, you ask, what is it?

 🤔 We are here to learn about Liesegangen rings.

Liesegangen rings are bands that typically cut across the bedding in sedimentary sandstone. Bedding refers to the layers of sedimentary rock, with each individual layers known as a bed. 

Liesegangen rings are diagenetic structures. Diagenesis means the change of a sedimentary rock, after initial deposition into a different form. It can take place due to a chemical, biological and physical change due to reasons such as temperature, pressures, and saturation with groundwater. They are formed due to authigenesis, which occures when a mineral deposit is produced where it is found. In the case of sedimentary rocks, authigenesis is due to precipitation or recrystallization of a mineral, commonly in the case of Liesgangen lines, the mineral is iron. 

🤔 Liesegang supersaturation-nucleation-depletion cycle.

This is a long name isn't it? So lets simplify it, the rock is porous, which means that water and other liquids can pass through it. Minerals such as iron are carried in this water, though at times, parts of the rock got supersaturated. Imagine a sponge which is filled with water - it is supersaturated. Then the minerals start to move by diffusion to other parts of the rock, so to produce a balance in the amount of the mineral. Though at times, localisation of minerals due to precipitation occurs, and crystal seeds form, these crystal seeds form bands, which in the case of Lieegang bands are known as rings. At times next to the rings you can get depletion of mineral in the adjacent areas, this may be apparent in differnce in colour or different chemical makeup when further analysed, which is beyond the realm of this EarthCache. 

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 Liesegangen here, in terms of shapes and colours. 

2. What process causes them to form?