Castleton lies at the northern rim of the Peak District limestone area. The Hope Valley comes up from the east and culminates here in Castleton. It ends at the Winnats Pass. Hope Valley is very nice, but also very well visited and crowded in the summer months.
There are four show caves and one wild cave around Castleton, three of them with mining background. The fractures in the limestone contain Calcite and sometimes lead ore and Blue John, a dark blue variety of fluor spar. Odin Vein was mined in the ancient surface mine Odin Mine. Today, the limestone is used to produce cement.
The geologic map shows the situation: The Hope Valley itself is formed in the Namurian Edale Shales. The southern and western slope of the valley is forme by a fossilized reef from the Visean (see geologic map below for more details). All the caves are located inside this reef.