This area was a limestone quarry during the 18th century and was converted to a reservoir in the 19th century, but this was closed in 1986.
It now includes areas of species-rich grassland, scrub and wetland, as well as being an important geological site. It is a Wildlife Reserve managed by Scottish Wildlife Trust.
These quarries illustrate a sequence of sedimentary rocks which were formed about 325 million years ago during the middle of the Carboniferous Period.
The main rock is a band of limestone formed in what was otherwise a predominantly volcanic environment.
This limestone, called the Petershill Limestone is famous for its well preserved marine fossils. These are of immense significance and many species have been described from this site.
Thick beds of limestone are visible at the southern end of the quarries. The Petershill Quarries are a Site of Special Scientific Interest (SSSI) due to them being a good example of rocks of the middle Carboniferous Period and also because of the lowland neutral and calcareous grassland.
The geological importance of the site is down to the limestone reef which is full of fossils. The reef was formed over 330 million years ago in shallow sea or lagoon when volcanoes were active and the ash and lava flows built up to eventually form the Bathgate Hills.
The fossils that have been found at Petershill include corals and sponges, crinoids (sea lilies) and molluscs – species that all lived in shallow tropical waters during Carbonifereous times. If you have any interest in geology then it’s worth a visit to this interesting site. However, tempting though it is to take a fossil home, you are encouraged to leave any you find just where they are.
As for living wildlife, the combination of high humidity and limestone is quite rare so you will find various unusual mosses. Keep an eye out on the higher ground for the gorgeous greater butterfly orchid and many other pretty flowers such as fairy flax and twayblade.
If you are more interested in the fauna you can find at Petershill, look out for squirrels, badgers, brown hares, rabbits and roe deer which are regular visitors to the nature reserve along with fifteen species of butterfly and moth and numerous species of birds.
You can learn more in this West Lothian Council leaflet
How to get here
From Junction 3a on the M8, follow directions for Bathgate until a roundabout is reached where the B792 (Kirk Road) is taken north west until a T-junction.
Turn right at the T-junction and follow Drumcross Road eastwards and up the steep hill out of Bathgate.
At the top of the hill there is a sharp bend, after which there is a very small parking area (for about 2 cars) on the left. Visitors are asked to park responsibly and not restrict access either to the working farm or farmers’ fields at Petershill.
There is a small car park on the side of the road where the reserve is marked with a wooden signpost, but it’s easy to miss as it can get a little overgrown. There is only room for a couple of cars – take care not to obstruct entrance to the field adjacent. Park up and head over the stile to follow the footpath around the perimeter of the reserve. It can get pretty wet and slippery. It is best for both safety and to protect the fragile environment to stay on the footpaths.
As you begin walking you can take in all the geological exposure which plunges down to the left, before heading into a more wooded area and then through a rather lovely meadow towards the northern end of the reserve. In the summer this meadow blooms with a variety of flower including orchids. The path then heads south over a wooden footbridge and veers down towards a lagoon which tends to be dry in summer but filled in winter months.