Introduction
I remember reading somewhere, some time, in a geology related article, the idea that nature takes everything and puts it in the sea and, while this is of course an enormous generalisation, it's not massively far from the truth - although I'd have qualified that claim by tagging the word eventually on the end, and perhaps slowly and not all at once 😉.
I've been doing a bit more reading lately over broad swathes of geologic time and the processes of plate tectonics and came to understand that, very generally speaking, any rocks which poke up above sea level to form dry land are constantly pulverized, broken down and transported by natural forces - wind, rain, sun, snow, ice, flowing water, wave action, gravity etc. - and of course human beings (sometimes with huge machines) - until eventually, one way or another, they end up back in the sea!
Don't worry though! The rocks you need to look at for this EarthCache are very much on dry land - or at least what's left of them are 😄.
The building stones which are the focus of this EarthCache have been under constant attack, from the elements and from human activity, since the day they were placed, and on some of them the damage is substantial, easy to see and rather interesting 🧐.
Logging Tasks
IN ORDER TO COMPLETE THESE LOGGING TASKS PLEASE SEND US YOUR ANSWERS USING THE Message this owner LINK AT THE TOP OF THIS PAGE OR USING THE MESSAGE CENTRE OR EMAIL VIA OUR GEOCACHING PROFILE BEFORE SUBMITTING YOUR LOG. PLEASE DO NOT INCLUDE ANSWERS OR SPOILERS IN YOUR ONLINE LOG. YOU CAN GO AHEAD AND LOG YOUR FIND AS SOON AS YOU HAVE SENT YOUR ANSWERS IN ACCORDANCE WITH GROUNDSPEAK GUIDELINES. LOGS WITHOUT ADEQUATE LOGGING TASK EVIDENCE MAY SUBSEQUENTLY BE DELETED.
You'll need to visit the three locations detailed - the published coordinates plus the two additional waypoints. Based on your observations at these locations and the information on this page you should be able to tell me:
- Describe the location(s) and appearance of the red sandstone that's in the WORST condition.
- Describe the location(s) and appearance of the red sandstone that's in the BEST condition.
- At the published coordinates, you will find some delaminated sandstone - what is the angle of the natural laminations in this stone and does the delamination match that angle or not?
- In the town square, immediately opposite the Stage 2 waypoint, you'll find a sculpture called The Scutcher, a mine worker using a steel bar to stop a rolling iron ore tub. The statue is made from iron ore dust combined with resin. Please upload with your log a photograph of yourself - or a personally identifiable item - alongside The Scutcher.
- The railway station (Stage 3), like the other buildings, has dressings of red Triassic sandstone. The main part of the building though is constructed from igneous rock - a pale pink microgranite from the Eskdale Intrusions, which cooled and solidified around 450 million years ago. But this microgranite isn't entirely pink. There are other colours and specifically some deposits of dark red haematite - an important ore of Iron. Please describe what colours you see in the crystals and what percentage of them are haematite.
- Optional task: feel free to add any photographs of your visit that do not show the specific features from the logging tasks - no spoilers please. In the interests of allowing everyone to experience the EarthCache fully for themselves obvious spoiler photographs will be deleted.
Background
Following the discovery of iron ore at nearby Hodbarrow (some of the best ore in the world as it turned out) Millom was transformed from a handful of vilages and farms to a prosperous town with a population of over 10,000 people and one of the largest industrial sites of its type in the world.
Much of the evidence of that industrial activity has disappeared but the building stones used in the most prominent buildings of the time remain in and around the town square.
In particular I noticed a lot of brick-red Triassic sandstone used as architectural dressings i.e. around windows and doors and along the bases and corners of wall elevations.
What was perhaps more interesting was the wide variation in the condition of these sandstones and the effects on them of sustained attack on their structure by the elements and their environment.
The red sandstone in the image to the right is in lovely condition. Examples on some of the buildings are in a far more sorry state 😥.
I started to wonder about why this should be the case, given that all these buildings are roughly the same age and so have been under attack for about the same length of time...
Lots of Lovely Layers 😍
Clastic sedimentary rocks - like these red sandstones - are deposited in layers, before being compressed and cemented into solid rock.
Layers look nice - but they, or rather the surfaces which separate each layer from the next, known as bedding planes also represent weaknesses in the rock along which the rock will tend to split or fracture when subjected to stresses.
Such weaknesses also represent easy targets for erosive forces (wind, water, ice etc.) which attack the rock's structure and break it down over time.
Layers wider than 10mm are called beds. Layers less than 10mm in width are called laminae. Sedimentary rocks can include both beds and laminae.
Weathering and Erosion
Weathering is the breakdown of rocks at the Earth’s surface, by the action of rainwater, extremes of temperature, and chemical and biological activity. It does not involve the removal of rock material.
Erosion is the process by which rock material is worn away and moved elsewhere by agents of erosion such as wind, water, ice and gravity.
Weathering and erosion are quite easy to spot on carved stone. Examples include discolouration (usually darkening), flaking surfaces, cracks, smoothing of sharp edges, general softening and loss of detail of the carved forms and parts which have broken off / gone missing completely.
Incorrect Bedding
One of the best known causes of failure in sedimentary building stones is incorrect bedding.
Layered stone placed upright rather than flat is structurally much weaker and made more so if water manages to penetrate weaknesses in the stone, namely the bedding planes formed when the rock was laid down.
And so, in order to prolong the life of the stone by reducing the damage caused to it by erosive forces, the stone should be laid on its natural bed, with its layers / bedding planes approximately horizontal. A stone laid on its top or bottom bed will resist weathering for longer. Face bedded or joint bedded stone will weather and break down quicker.
Delamination - Not What I Thought It Was? 🤔
The image to the right shows a block of building stone which has been face bedded.
It's clear to see that the builder has positioned the stone such that the laminae (layers in the stone) are vertical rather than horizontal - especially if you look carefully down the end of the block exposed on the left hand side.
It's also clear to see that parts of most of the laminae, weakened by weathering, have peeled away from the exposed face, and been eroded away.
This is what I expected delamination to look like - the loosening and removal of laminae naturally present in the rock - but it seems that's not necessarily the case! 😯
It turns out that, in the strictest sense, delamination is a mode of failure where material fractures into layers - which means that delamination can occur in materials which don't necessarily incorporate layers to begin with.
Or, put another way, delamination in building stones doesn't necessarily have to follow the direction of existing layers in the rock. Which means that building stones which have been correctly bedded can still suffer delamination!
Contour Scaling
The image to the right shows a block of building stone with delamination on its exposed face.
If you look closely though (click on the image for a larger view) you'll be able to see the fine, parallel laminae running diagonally, up and to the right - which means that the delamination in this block bears no relation to the naturally occuring layers in the stone. This form of delamination is also known as contour scaling - probably because it resembles the contour lines used to indicate height on a map.
So what's going on here? Why is nature's attack on the stone not splitting the stone along the natural planes of weakness between its naturally occuring layers? Could it be that this stone is being weakened in other ways? Was it weak to begin with?
You Get What You Pay For?
Not all sandstones are created equal.
Some sandstones are very hard, being well compacted and cemented, and resist weathering well, and will be considered superior and valued more highly. Others are much softer and some sandstone deposits even include pockets of unlithified sand. The Sherwood Sandstone Group, of which these sandstones are almost certainly a member, are a bit of a mixed bag.
In terms of cost though there's a balance to be achieved. On top of the cost of quarrying the stone there's the cost of shaping it into blocks - and harder stone takes longer and so costs more to carve.
It is likely therefore that superior stone will be found in buildings of higher status where quality, appearance and durability were considered more important than cost. Conversely, less prestigious buildings with lower budgets may have been restricted to less robust building stone - or even moulded clay bricks.
There's also the question of whereabouts on the building the stone has been used. Some parts of the building, at ground level for example, will come under more prolonged attack from weathering and erosion than other parts.
Porous sandstones at ground level will tend to hold moisture longer than stone used higher up in the structure. Especially in the Winter months, when roads and paths are salted to keep ice at bay, the water soaking the stone will tend to contain high levels of salt in solution. As the stone dries the salt re-crystallises and these crystals, as tiny as they are, gradually lever off layers of rock which can then be eroded away. This is one possible explanation for the appearance of contour scaling.
If you've carefully read and digested the information from this cache page your tasks at the cache location should prove relatively straight forward, although you may wish to take a printed copy of the page with you so that you can check your answers while there 
.
Please submit your logging task responses before posting your log.