The City of Edinburgh boasts some of the most beautiful buildings in Europe, built using stones quarried right on our doorstep. In fact the builders were spoilt for choice, as the city rests upon an area which over time acquired a wealth of stone suitable for the purpose. 350 million years ago this land was a tropical shoreland with lagoons teaming with marine life (carboniferous period). During this time, volcanic eruptions formed the Seven Hills of Edinburgh, The Great Forest of Drumselch covered the land, and the mighty trees became massive coal seams. Large rivers lay down thick sedimentary rocks and sandstone beds. Then 2.4 million years ago the Ice Age advanced then retreated, leaving glacier melt water to form new rivers and valleys. The end result of this geological turmoil was a land blessed with superb stone resources which were used for the construction of both the Old and New Towns of Edinburgh. There are 2 main types of stone used in Edinburgh buildings: dolerite or diabase - known locally as whinstone; and sandstone.
Sandstone is the dominant rock type used in Edinburgh's buildings. It is a sedimentary rock which originated as loose grains of sand at the bottom of seabeds or deserts, beaches and rivers, and then transported by water or wind to its final resting place where the grains are stuck together with a variety of different materials such as silicates and clay. The final appearance and building characteristics of the sandstone will depend on how it was transported (this affects the grain size) and how the grains are held together. As a generality, sandstone is much appreciated by builders owing to its variety of colours and its strength while still being able to carve and decorate it.
Whinstone or Dolerite or Diabase is the other main building stone of Edinburgh. It is an igneous rock which was formed from molten magma which failed to reach the earth's surface during a volcanic eruption. Salisbury Crags, where James Hutton inspired modern geology, is a magnificent example. Whinstone is a very hard rock, often used in roads and kerbs.
In the case of both sandstone and whinstone builders have used the stone as either 'rubble', that is to say neat, or just as it came out of the quarry and only cut to fit; or 'dressed' which means that the stonemason took more time to shape, smooth and decorate the stone. I imagine that this choice would likely have depended on the size of the budget!
This EarthCache will take you to a very interesting square in the heart of the University quarter of Edinburgh, where you can see some old buildings built with both sandstone and whinstone.
You should be on the west side of George Square in front of a lovely terrace of houses with walls built from both sandstone and whinstone. The sandstone came from Craigmillar and Hawkhill quarries around 1766-85. This same stone was also used to build Craigmillar Castle (late 14th century), the Palace of Holyrood (1532), Parliament House (1636) and Edinburgh Castle (1639). This Craigmillar stone was considered relatively impermeable to water so was later used in the construction of Edinburgh's reservoirs and Leith docks. The darker whinstone came from the quarries at Salisbury Crags.
YOUR TASKS
Study the walls. Please do not leave the pavement, go up any stairs, or look into any windows. Although the University has given permission for this EarthCache, you should be aware that there are also some private properties. Please be discreet and use common sense during your visit.
Please carry out the following:
- Look at the the walls. Send me a description of what you see, you should mention as a minimum: the size of the blocks; their colour; are they 'rubble' or 'dressed'; how they are arranged; what is the approximate ratio of sandstone to whinstone? and any other observation you notice.
- Send me a sketch with labels pointing out the sandstone and the whinstone. I will also accept a photograph of a section of the wall which you have edited to add the labels.
- Now stroll down the road towards University Library and the Meadows. Many famous people have been associated with these houses and are commemorated on plaques. Send me the names of FOUR of them.
THANK YOU FOR VISITING, I hope you enjoyed it. I look forward to reading your answers and admiring your photos, but please do not log photos that are spoilers. PLEASE also do not post your answers in your log, send them to me either by email or by the message centre. You MUST send me your answer within one calendar month, please, or else I shall delete your log. IMPORTANT: It is a requirement of logging this earthcache that you attempt to answer all the questions. Your log will be deleted if I don't receive your answers within one calendar month of your log. Please also use the date you were actually there, not the date you wrote up your logs or some other date. Thank you.