The White Peak area of Derbyshire is porous! Water soaks away through the rock and there are rivers around here which disappear into swallow holes, so called because the water is swallowed up and runs for a while through underground channels, only to reappear further downstream. While this is not true of the Dove, there are a number of features in the area formed by the erosive power of water over long ages of time, one of which is caves.
Like these, along the gorge from Milldale, named Dove Holes; caves created by the water wearing out the soft limestone cliffs. They are not of any great depth, the arched entrance being the most impressive feature, but they are still popular for a quick explore.
A little further downstream, at the base of Ilam rock is another cave entrance, not so grand nor so noticable, requiring a deal of stooping to ensure safe entry, but which opens up into a surprisingly roomy space.
In places, the walls of this cave are smooth, worn down by seeping water, like the pebbles on a beach or rocks on a river bed. Appropriate, considering that this whole area was once a tropical sea!
Look more closely and you can see glittering traces of minerals; quartz and calcite and feldspar, washed down through cracks in the limestone rock - rather like stalectities formed on the surface of the cave wall.
Post script: Caves along the valley were used as shelters by hunters during the last ice age, which was around 14,000 years ago. Around 4,500 - 5,000 years ago, early farmers were using some of these caves as burial chambers and in Roman times, around 2,000 years ago, shepherds used the caves as shelters.