Sheffield Central Library and Graves Art Gallery
The Graves Art Gallery was built with the support of business man John George Graves, who made his fortune out of one of the country’s earliest mail order businesses. Graves also gifted his art collection of almost 700 paintings, much of which can still be seen today.
Built in a broadly art-deco style, it was opened in 1934 after work on the building began in 1929. Conceived as part of a plan to create a civic square, it was the only element ever built and so faces onto a narrow street. Tudor Square to the side of the building was created separately and more recently. The building, supported by a steel frame, is faced with Portland stone. It is the Portland Stone that is the focus of this Earthcache.
Portland Stone
The Portland Stone is a limestone. Limestones are mostly made of calcium carbonate. This comes originally from the bodies of many small organisms which build their framework out of calcium carbonate crystals. When these organisms die they accumulate and become fossilised over millions of years. These became coated with layers of lime mud, and formed small balls. Over time, countless billions of these balls, known as "ooids" or "ooliths", became partly cemented together by more calcite, to form the oolitic limestone we call Portland limestone.
Portland Stone originates from the Isle of Portland in Dorset. It is one of the most popular building stones in Britain, being popularised by many famous London landmarks such as The British Museum, The National Portrait Gallery, St. Paul’s Cathedral, the Cenotaph and BBC Broadcasting House.
The fossils can clearly be seen in the rock as it begins to erode. It is these fossils that you are here to see!
Logging your Find
In order to log your find, please send a message to my profile answering the below questions. There is no information about the stone around the library, so you may need to do some research to answer these questions, the answers to which are freely available on the internet.
In addition to the below questions, optionally upload a picture of yourself or your GPS with the largest fossil you can find. You can log your find immediately, but please send the answers within 24 hours. I will respond to your email as soon as I can. Logs where incomplete answers have been given, or where an email has not been received, may be deleted.
- Answer the following questions anywhere around the building.
- Describe how the stone looks and feels.
- Look at the fossil fragments that have been revealed as the stone erodes. What type of creatures do you think these are?
- What does the habitat of the creatures tell you about how and where the stone was formed?
