For many Gollinrod Gorge means a narrow valley with ancient woodland, the river Irwell, and geology. For others it is a hidden spot, only known to few. This earthcache, takes you to a hidden spot, past which many people walk every day. The co-ordinates take you to a wooded area, though as you enter the wood, you will notice all is not what it seems. Ruins cover this area, and the ground is uneven, with holes here and there. Here is the site of the Ocean Chemical Works, which at during its history produced alkalis and cyanide. Yes, cyanide, to think this now peaceful spot produced something which caused death. Take care as you look around, as whilst there is still a lot to see, it is an old industrial site.
So why have I brought you here?
Looking around the Gollinrod Gorge area, the geology is from the carboniferous period, which around here means sandstones, mudstones and other similar sedimentary rocks from that period. An example of a local rock can be found at GC5V47N The Tups Bottom. Chocolate Brownies, where Haslingden Flag can be seen. Ramsbottom forms part of the the Rossendale valley, and its geology was formed millions of years ago at a time when the whole of what is now the North of England was covered by huge river deltas and lagoons. It is believed that sediments, mainly sands, silts and muds, were eroded from hills in an area that now includes Scandinavia and Greenland and were swept into vast river deltas and lagoons in a central basin in a position now occupied by the Pennines. The sediment settled to the bottom as the water slowed down in the deltas and lagoons. The nearest equivalent sediments of today are forming in huge river deltas such as the Mississippi delta. The sediment built up until it was hundreds of metres thick and was gradually compacted and cemented into the “sedimentary” rocks we know today. It took place in what is known as the Upper Carboniferous, about the middle period of obvious life on earth.You would have thought that the factory, would be positioned to make benefit of the geology, but in reality in order to make alkalis it needed something different. That was calcium carbonate, in the form of chalk.
So what is chalk?
Chalk is a soft, white, porous sedimentary carbonate rock, a form of limestone, composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute shells shed from micro-organisms called coccolithophores.
Chalk can be found in many places in the UK, but is commonly associated with the White Cliffs of Dover, and the North Downs in Kent, which was laid down under the sea during the Upper Cretaceous period, and was later uplifted at around 65 million years ago.The Cretaceous was a period with a relatively warm climate, resulting in high sea levels and creating numerous shallow inland seas.
Diagram showing the different geological periods, two of which relate to Gollinrod Gorge, one through nature and the other through man.
Research about millstone grit areas, shows that waters are generally well buffered at a neutral pH ( 7.0) but more acidic waters (pH<5) occur locally in some areas. Chalky or lime-rich soils may be light or heavy but are largely made up of calcium carbonate and are very alkaline (they have a pH of 7.1-8.0). Ph is a scale that runs from 1 top 14. An very strong acid may have a pH of 1-2, whilst a very strong alkali may have a pH of 13-14.
The chalk will have been crushed when it was used in the chemical works here, and there is still quite a bit to see, you just need to look closely.
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 identify what haslingden flag looks and feels like, you can go to the above mentionned earthcache for this.
2. Please find some chalk, what makes you think that it is chalk and not native geology? Please explain what it looks and feels like. How big is your bit of chalk?
3. Why is chalk not found in this area naturally?
4. Please form an imaginary 1m x 1m square, how much chalk can you see in it? Please tell me in a percentage. Under normal geological conditions how much in a percentage should there be of chalk here if the chemical works had not been built?
5. How do you think that the ph of the chalk will have affected the local plantlife?