Castles & karst |
Lithology & geological setting
![Picture](/uploads/5/0/4/5/50450907/1430343118.png)
The Castleguard karst is developed in large carbonate rocks of Middle Cambrian age. Above them are more than 525 m (1,700 feet) of shales, mudstones, thin sandstones, and dolomites of the Middle Cambrian/Ordovician formations.
Dolomite interbeds are an important part of the upper formations, because they reduce the solubility. As a result, the karst landforms in the area are limited in type, size, and quantity. However, important underground drainage developed within the outcrop at Mt. Castleguard.
The shaley Stephen formation is a partial aquiclude. At the broadest outcrop, it allows for normal drainage at the surface, and some springs rise at its contact with the overlying Eldon formation. However, being only a partial aquiclude, beneath Mt. Castleguard, it is known that Eldon groundwater infiltrates the Stephen rocks and pass through, getting into the Cathedral limestone below. The Cathedral limestone is dense and is the principal karst formation. Its upper unit is predominantly soluble, and hosts the greatest density of sinkholes. Castleguard Cave is also contained within the Cathedral limestone.
Dolomite interbeds are an important part of the upper formations, because they reduce the solubility. As a result, the karst landforms in the area are limited in type, size, and quantity. However, important underground drainage developed within the outcrop at Mt. Castleguard.
The shaley Stephen formation is a partial aquiclude. At the broadest outcrop, it allows for normal drainage at the surface, and some springs rise at its contact with the overlying Eldon formation. However, being only a partial aquiclude, beneath Mt. Castleguard, it is known that Eldon groundwater infiltrates the Stephen rocks and pass through, getting into the Cathedral limestone below. The Cathedral limestone is dense and is the principal karst formation. Its upper unit is predominantly soluble, and hosts the greatest density of sinkholes. Castleguard Cave is also contained within the Cathedral limestone.