History
St. Giles is a medieval church but little remains. It was restored by Thomas Chambers Hine in 1872 and again by Naylor and Sale between 1896 and 1911.
Features
It retains a medieval screen from the late fourteenth century. There is some stained glass by James Powell and Sons.
However, the focus of this earthcache is based on a particular feature of the stonework of this church:
Millstone Grit
Millstone Grit refers to a variety of sandstones, which were formed about 300 million years ago. It was deposited as part of a vast river delta system, formed where the river met an ancient sea. The sand and grit material was washed down from a range of ancient mountains formed between 430 to 380 million years ago, during the Devonian period, when the modern day North America collided with Europe. The sediments were later eroded and deposited some 60 million years later in the Carboniferous period. Derbyshire in particular is one of the most important producers of this sandstone, which is used in many buildings, including churches around the East Midlands.
Sandstones are mainly composed of grains of the hard mineral quartz which is crystalline in appearance. These quartz grains are usually angular when smaller than about 0.15mm but rounded by attrition when larger. The name 'grit' is used for many local sandstones and indicates the coarseness of the quartz grains in the rock, although the size of the particles in the sandstone is variable.
Over time, stones used for building can become discoloured. This can happen due to a number of reasons, which are: biological soiling, particle soiling and staining. Stone can become biologically stained when organisms such as algae, lichen and bacteria begin to grow on, and in the stone. Particle soiling can occur as pollution, such as fumes accumulate on the stone, staining the surface and making it blackened. Finally, staining occurs when darker minerals present in the rock gradually reach the surface.
Stone can suffer erosion from weathering, such as by the wind or rain. The wind can erode buildings by deflation (the removal of loose, fine-grained particles by the turbulent action of the wind). Rainfall causes weathering by the combination of the raindrops hitting the surface of the stone and fracturing it, and the running water carrying particles away.
We see evidence of the use of millstone grit in the church tower of St Giles, and this earthcache will look at some of the properties of this as stone which made it a popular choice for a key building material.
In order to log your find, please answer the following questions and send your response via email or via the Message Centre.
1. Describe the colours and texture of the millstone grit of the church tower (which is on the west side of the church). Can you see any minerals within the millstone grit, and if so, what are they?
2. Do you see any evidence of erosion and/or pollution of the stone. Explain your findings. Optional - You may also like to look in through the gates on the porch - to the left there is the old triangular window frame, potentially from the 14th century. Explain the weathering process that would have occurred.
3. Millstone grit dates back to a particular stage of the carboniferous era. What is it called?
4. What other uses can you think of for this type of stone (think about the name)!
5. Please feel free to take any photos of yourself at GZ (these are an optional extra and not compulsory)!
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For full information on how you can expand the Church Micro series by sadexploration please read the Place your own Church Micro page before you contact him.
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