Using only an Ordnance Survey map of Castleton, you can tell that it is a limestone area. Firstly there is a long distance footpath named the Limestone Way (starting at 151 827 and continues in a south-westerly direction), which suggests that there is limestone nearby.
There are also 4 caverns, Blue John Cavern (131 832), Treak Cliff Cavern (136 831), Speedwell Cavern (139 827) and Peak Cavern (148 826). This suggests that there is pervious rock underneath the Castleton area. This could be limestone, because caverns are formed when water runs along the bedding planes and down joints which are found in pervious rock, will widen by the weak carbonic acid in the water dissolving the rock. This is called chemical weathering. Running water also brings with it sand and stones that wear away at the joint and eventually enlarge it. Thus the cave begins to be formed. As the cave becomes larger the stream will run down different joints in the roof, dissolving away the limestone and so forming a cavern. The pervious rock also explains the absence of surface water, such as rivers or marshes etc.
There is also a quarry located near Castleton, between Pin Dale and Smalldale at around 160 817, which indicates that there is a source of valuable rock, that has been excavated for uses such as buildings. Therefore this rock could be limestone as limestone has many uses, such as for building, the manufacture of lime, the manufacture of cement, crushed limestone is used to reduce acidity in soil, and it is used along with other materials to make glass. Also next to the quarry, at 167823 is a works (symbolised by Wks), which could be a cement works if the stone quarried is limestone, because of its use in production in cement, which is another clue towards Castleton being a limestone area.
There are also several disused mines in the Castleton area, located at 124 808, 133 802, 140 802, 143 802 and 124 808, which also show that there is a good source of valuable rock, such as limestone, which could have been used to build nearby houses years ago when the mines were in use.
