GEOLOGY 



several feet in depth, and visitors are conveyed along it in boats. The 

 excess of water falls over the edge of the platform with a deafening 

 roar into the lower part of the cavern known as ' The Bottomless Pit.' 

 This pit was explored by the Kyndwr Club in 1901, and the writer 

 descended with the party. The vertical distance from the platform to 

 the water surface was 63 feet, and the depth of the water was not more 

 than 22 feet. A vertical vein of calcite nearly 6 feet in width was seen 

 at the west end of the platform. 



The Blue John Mine near Castleton consists of large underground 

 cavities connected by artificial passages. It is supposed to have been 

 discovered accidentally in mining operations by the Romans. 



The Grand Cystallized Cavern is 60 feet long, 1 3 feet wide, and 45 

 feet high. Lord Mulgrave's diningroom is 39 feet by 36 feet, and 57 feet 

 high. The new cavern which has been described as the ' largest, the 

 wettest, the dirtiest and the most rugged and irregular ' of any of the 

 series measures 100 yards in length, 16 in width. This cavern leads to 

 the Fairy Grotto, a small cavern with delicate stalactites and stalagmites. 

 The total distance of the winding passages is said to amount to over 

 3 miles. 



The Peak Cavern at Castleton, which has a magnificent entrance, is 

 another example of a natural cavern connected with a system of under- 

 ground drainage. The water enters the limestone along a line of swal- 

 low holes near Perryfoot at the boundary of the Mountain Limestone 

 and shales. The water is finally discharged partly through the cavern, 

 but largely by a spring called Russett Well, and flows down the valley 

 joining the river Noe near Hope. 



Eldon Hole, a chasm in the side of Eldon Hill near Peak Forest 

 village, has been supposed to be connected by underground passages with 

 Peak Cavern. This supposition has not been proved. The chasm is 

 about 100 feet long and 20 feet wide at the surface. The sides are 

 almost vertical. In December, 1900, the writer and thirteen others 

 were lowered down this chasm by a rope. It was 180 feet deep. The 

 bottom measured 36 feet by 29 feet. The floor is composed of loose 

 angular blocks of limestone and slopes at an angle of 35. Climbing 

 down we reach a low archway about 3 feet in height which opens 

 out into a cavern. The slope of scree continues 40 feet further. The 

 cavern is pear-shaped in a nearly horizontal section, and measures 40 feet 

 from north-east to south-west, and 36 feet from north-west to south-east. 

 The lowest part of the cavern is 256 feet from the surface to the ground. 

 No stream of water was seen. 



Another system of underground drainage occurs near Eyam. The 

 water enters the limestone by swallow holes and finds its way to the 

 valley of the Derwent by way of Middleton Dale. 



The disappearance of the water down swallows often results in a 

 dry valley which represents the old watercourse. Linen Dale near Eyam 

 is one of these valleys. Great Rocks Dale through which the Midland 

 Railway passes between Miller's Dale and Doveholes is another dry valley. 



