Remember all normal precautions need to be taken when stopping in a lay-by near a busy road and by water.
This cache is just off the A44 where it splits to the B4343 to Devil's Bridge and an alternative scenic route to or from Aberystwyth.
There is a pull in near the cache for one or two cars or there is a larger area on the left just as you leave the A44. If you use this parking area please take extra care when crossing to the GZ as cars pass at speed coming from the A44.
The small stream is the Afon Castell on it's way to join the Afon Rheidol at Ponterwyd. From the bridge, you can see the old ruins of Castell Mine, which was worked in the 19th century to extract zinc ores along a fault that breaks the slate. The main vein minerals are calcite and ankerite (a carbon of iron and calcium). The ore is sphalerite (zinc sulphide). The veins were deposited about 355 million years ago, during the relaxation at the end of the Caledonian collision, after it fractured rocks and opened pathways for the metal solutions.