Before it became an RIG (Regionally Important Geological Site) owned by The Scottish Wildlife Trust, Petershill contained two reservoirs that supplied the drinking water for Bathgate until the early 1980's. It became part of an SSSI (Site of Special Scientific Interest) in 1976. From the late 1700’s it operated as a limestone quarry for approximately 100 years.
Petershill is unusual in that it contains a reef of limestone in an otherwise volcanic area. The limestone reef was formed in the carboniferous era 330 million years ago. It was formed at the bottom of a shallow, tropical sea from the skeletons and shells of the marine creatures that lived there. They were crushed and compacted together by the weight of the water to form rock.
The active volcanoes in the area covered everything in ash and lava, burying the limestone and building up a volcanic pile that now forms the Bathgate hills.
Scotland was not always in the position that it is in now. It was part of a larger continent that straddled the equator. It had a climate similar to that of the Bahamas today.
The movements of the earth’s crust caused tilting of the rock layers bringing them to the surface. Weather erosion eventually exposed the limestone.
The limestone that you can see at Petershill is very finely grained; it started off as a mud like substance. It is called a bioherm. It has a high carbonate content which reflects its main composition of skeletal remains.
The fossils here represent the types of creatures that thrived in the environment.
There were corals, sponges, crinoids (sea lillies), trilobites, gastropods (sea snails), brachiopods and molluscs.
In order to log this EarthCache please send me the answers to the following.
- In your own words give a short description of the limestone reef.
- What type of fossil is most abundant here?
Walk a little further along the track to the south, paying particular attention to what is under your feet. Can you find some “spaghetti rock”? (You may need to go up the slope a little way).
- What fossil do you think is in the spaghetti rock?
- Describe what you think this area would have been like 330 million years ago.
- (optional question) What do you think this area will be like 330 million years from now?
Practicalities
There is parking for 2 cars at the waypoint given. Please do not park on the farm track to the west of the site.
Be careful, the way into the reserve is along a narrow, muddy and in places a steep track.
Do not remove fossils from the site and adhere to the Scottish Fossil Code.
After your visit to the limestone reef you can enjoy a short walk around the reserve and look for signs of its more recent past.
Thanks to the Scottish Wildlife Trust for permission to place this EarthCache.