Collins New Naturalist Library

Another feature of the dale that is easily overlooked is the fact that it follows a winding course. One result of this is that the vistas are usually not long but are closed in by a succession of rocky pictures often of great beauty. As each bend of the gorge is passed there come into view new cliffs, fresh and fantastic shapes or even a cave, such as Dove Hole and Reynard’s Cave. These last are a reminder that the excavating of the dale has not been entirely due to the direct deepening of the river channel. Disappearing streams like those of the Lathkill and the Manifold have played their part by dissolving underground passage-ways beneath the floor of the dale which became open to the air and the sunshine, in the way already described for Lathkill Dale, and henceforth became part of the main dale. The two caves just mentioned were formed by tributary streams which, however, were drained dry when the Dove itself deepened its channel below their level.

The winding of the dale is reminiscent of the meanders of a river flowing along an alluvial plain. When such a river is rejuvenated the knick point, followed by the deepened channel, travels upstream along the meandering course round bend after bend. Such was the history of the Dove when, with the mid-Pliocene uplift, it became rejuvenated and incised its new valley into the early Pliocene peneplain, and at a later date excavated the dale in the floor of that valley.

At last the explorer comes to the end of the dale and finds that it opens out into a normal valley. From this point up to its source on Axe Edge it does not flow over limestone but over shale with some grits. As already seen these shales yield much more readily than does limestone to the destructive influence of rain and frost. When therefore this uppermost section of the river came under the influence of the latest rejuvenation, the sides of the deepening channel were more rapidly worn back and a wide valley formed.

THE MOORLANDS

The striking change of scenery met with along the upper reaches of the Dove is a reminder that the limestone uplands form only part of the Peak District; the other part is made up of grits and shales. The change reflects the still greater contrast between the uplands and the moors. This gives to the district much of its attractiveness as is typified by the streams of visitors to the dales and the comparative trickle of energetic hikers who make the lofty, windswept moors their main objectives.

The rocks which form the moorlands completely encircle the uplands like the oval frame of a beautiful portrait. At the top of the frame, where the grits have their maximum thickness, the moulding stands out in bold relief. Along the sides this declines and at the bottom it almost disappears for the grits become much thinner as they pass southwards round the limestone. On the south such features as they produce still remain largely hidden under ancient covering of Triassic sands and marls.

In the uplands the limestone is almost uniform in character, but in the moorlands extremes meet and resistant grits lie in close juxtaposition with the much more easily weathered shales. This is illustrated in The Peak itself which is capped with a mighty slab of grit, several hundred feet thick, resting on a pedestal of shale. The slab forms a plateau bounded by steep rugged cliffs. The pedestal is flanked by slopes whose surface is roughened by landslips or broken by steps caused by the presence of occasional thin beds of grit.

The rock of the plateau is so porous that rain-water soaks into it rapidly and, percolating downwards, saturates the lower layers. This great slab of grit therefore functions as an underground reservoir having an impervious floor but is without retaining walls around its margins where, at the junction of the two kinds of rock, the water leaks slowly away and is lost. Within the grit the water flows freely through the fissures but elsewhere its flow is hindered as it seeps slowly through the fine pores of the rock. Unlike the water-table of an ordinary open-air reservoir, the surface of which is perfectly flat, that in the grit is heaped up in the centre and slopes thence in all directions.

Wherever a valley has been developed on the plateau deep enough for its floor to reach the water-table, water escapes and forms a stream flowing along the valley bottom. Elsewhere the plateau is dry and streamless.

At the base of the cliffs bounding the plateau water leaks away perpetually and, soaking into the adjoining shale, softens it to such an extent that it yields to the pressure of the overlying rock and is slowly squeezed out. The cliff, with its foundation thus weakened, eventually collapses and tumbles its fragments down the slopes. It is in this way that the slabs of rock which cap the highest grounds in the district have been and are being worn away gradually, so that large plateaux in time become small ones, e.g. Brown Hill and Stanton Moor, and small ones become conical peaks or pikes such as Win Hill near Hope and Oaker Hill near Matlock.

Where a crack or fissure running through the rock emerges at the cliff-face a copious spring of water gushes forth. At such a point the destructive action just described takes place more rapidly and leads to the formation of a notch, a gully or even a “clough,” the floor of which is cumbered with fallen blocks of grit (Plate IV, see here (#ulink_af784047-a0de-5f0f-a97d-ee13bea8bb09)). All these features may be seen well developed round the margins of any grit plateau or along a grit edge.

Turn now to the pedestal which supports the rock. This consists mainly of shale with occasional thin grits. Each of these as it crops out to the surface acts as a protective covering for the shale below; but the shale above it is weathered into a concave slope. This merges downwards on to the flat upper surface of the grit which is exposed as a narrow platform.

The vicinity of Matlock Bank yields an excellent and easily accessible example of these types of topography. Standing in Salters Lane and looking across the valley, the step-like features produced by the sub-divisions of the Kinderscout Grit are well seen. They are indeed emphasised by the plan of the town in which main roads run parallel to one another along each shelf and are flanked by buildings which have developed along the ledges.

On the skyline above all this are Matlock and Farley Moors, which owe their presence to a small plateau formed by the Chatsworth or Belper Grit. This layer, however, does not lie quite flat but is bent into a broad shallow downfold having a slight southwards tilt. Rainwater falling on this seeps through the rock to the centre of the fold, where it accumulates as a valuable underground reservoir from which the Matlock Urban District draws its main water supply.

The vegetation cover of the plateau shows an interesting zonation of plants from those which flourish on very dry situations near the scarp margin where the ground level is high above the water-table, to those which favour the boggy conditions near the centre where the ground has dipped down to the level of the water-table.

On the southern margin of the fold the water from the reservoir spills out as a copious stream, the Bentley Brook. This flows for a short distance through a rock-strewn clough whose rugged sides suddenly diverge and pass into two long curving scarps which enclose a broad shallow valley excavated out of the underlying shale down on to the upper surface of another grit layer. This is a good example of a type of hanging valley which is frequently met elsewhere in the moorlands. After flowing for about a mile the stream plunges over the lip of the grit and sets out on a tempestuous journey down the steep valley side east of Matlock, cascading through Lumsdale in a succession of cloughs and ultimately joining the Derwent river.

Similar combinations of topographical features are met with repeatedly throughout the moorlands especially in its northern section. Here, as already seen, the underlying form of the region is based upon a dome-like arrangement of the rocks. Owing to the asymmetry of the anticline its crest lies nearer to the west side, a fact which accounts for the asymmetric position of the dominating features situated along the line from Kinderscout to the extreme northern end of the Peak District, where the influence of the Derbyshire dome ceases to be felt. There the moorlands have a minimum width of only about two miles as contrasted with twelve or more miles in the latitude of The Peak. Along the crest the higher members of the Millstone Grit series have been removed and the lower ones which are more massive dominate the scene. In association with the dip of the rocks away from the crest, the summit level declines most rapidly towards the west. Towards the north-east and east, owing to the low angle of dip, the grits and shales give rise to more widely spaced scarps and broader vales than those on the west.

Thus the general form and arrangement of the major features of the moorlands are controlled by the arrangement of the rocks. But these alone would have led to nothing more than a vast expanse of desolate and even repulsive moors. The area has, however, been redeemed from such a fate by the carving activities of running water. Everywhere are to be found streams fed from the inexhaustible reservoirs of the grits. These set out from the crest on their journey to the lowlands, carving for themselves narrow, often deep gorges through the massive grits. By joining forces they become larger streams. With their power increased and aided by associated agencies they excavate an endless variety of cloughs ranging from mere notches down the faces of steep scarps to narrow, wild and impressive valleys such as that of the Crowden Great Brook which opens on to the north side of Longendale. A swift torrent flowing down the western slope of Kinderscout starts as the Kinder Downfall, which is the only considerable waterfall in The Peak (Plate V, see here (#litres_trial_promo)) Two rivers, the Etherow and the Derwent, are the centres towards which many of these streams converge. The spacious valleys of these rivers have steep sides with the usual step-like grit features at successive levels crowned by magnificent scarps. In each case the left side rises more abruptly, forming a continuous feature of great grandeur only slightly broken by notchlike cloughs. On the right side the valley sides are less abrupt and are deeply dissected by larger valley-like cloughs.

In the northern outskirts of the drainage basin of the Derwent much of the Kinderscout Grit has been removed and has left the underlying shales with minor grits exposed over extensive areas. These are occupied by moors and mosses lying some 500 feet lower than The Peak. They also are redeemed from monotony by the presence of attractive tributary valleys, spacious but steep-sided.

East of the Derwent the outcrops of the Kinderscout Grit continue south as the East Moors. These are defined on the west by a series of prominent scarps (Derwent, Stanage, Froggatt and other Edges) overlooking the main valley. They dip at a steeper angle than that already seen in the north but carry a similar series of dip slopes and scarps. Here, however, the continuity of the latter is interrupted by the transverse folds already mentioned. They give rise to structural and surface features like those described above in detail for Matlock Moor.

In the West Moors, between Buxton and Macclesfield, the geological structure of the district reaches its maximum of complexity in sharp north-to-south folds crossed by minor ones trending west to east, thus producing an area of intermingling types of scenery like those already described but on a smaller scale, surrounding or enclosing in their synclinal hollows patches of lowland types due to the presence of pockets of Coal Measures and even of Triassic rocks.

One more element in the make-up of the district remains to be mentioned. The Edale Shales which lie between the limestone and the grit have a maximum thickness of some 1,000 feet. Under normal circumstances it should crop out as a relatively broad zone between the limestone uplands and the moorlands. Owing to cross-folding and faulting, especially in the west, the zone is broken into a number of separate patches which give origin to the gracious landscapes of Darley Dale, Edale, overlooked by Mam Tor (Plate VIb, see here (#litres_trial_promo)), and Hope Dale. The more extensive patches lie outside the area to the south and south-west.

THE WORLD UNDERGROUND

Reference has already been made see here (#ulink_db329224-d24e-5d91-aa42-ec496e5ff054) to the formation of caves as a common feature of the limestone area of The Peak. The exploration of these caves under proper auspices is a challenging form of recreation for the physically fit, exciting but rigorous, while many of them are of special scientific and archaeological interest. Some of the larger and more spectacular examples are exploited commercially, like the famous Blue John Cavern (strictly the Blue John Mine), the Peak and Speedwell Caves and the Treak Cliff Caverns (Plate 2b, see here (#ulink_8fc9d959-31b9-5bd3-a90f-47c235ce3a5f)), all in the Castleton district, and are an unfailing attraction for the general sightseer, though they are not quite so impressive as those of Cheddar.

While the processes by which caves are formed are not disputed, opinions differ as to the conditions necessary for the processes themselves to operate. As already explained, caves mainly owe their origin to water action, either as a solvent in the limestone or as an agent for the transporting of rock material by which the beds of underground streams are scoured. The relative importance of each of these forms of water action doubtless varies with local conditions. Authorities hold different views, however, as to where, in regard to the underground water, the cave-forming processes take place. Some maintain that caves originate and develop above the water-table within what is termed the “vadose” zone, i.e. the zone between the surface and the level of saturation, within which water moves downwards by gravity. This view implies that water percolating downwards from the surface will dissolve almost all the calcium carbonate it can hold before it reaches the water-table. Others have shown that many caves must have originated below the water-table in the “phreatic” or water-logged zone. Regarding this issue much depends on such factors as the extent to which solutional activity may continue below the water-table and the nature of water movement resulting from pressure exerted in the phreatic zone. It is likely that each of the theories is applicable to certain caves. In many cases, since there is ample evidence in the Peak District, as elsewhere, of past changes in the level of the water-table, it is reasonable to favour a compromise involving the application of both theories.

Although the phenomenon of limestone caves has been widely studied in many parts of the world, there is scope for much further investigation. For this the Peak District presents an obvious field. As Dr. G. T. Warwick has pointed out, the need is for a careful examination of particular caves, including the basic work of surveying them, without which detailed study cannot be advanced. In this connection the recent work of Dr. Trevor Ford on the Treak Cliff Caverns is to be welcomed not only for its intrinsic value but as pointing the way for further investigations.

Caves are seldom found in the Millstone Grit and when they do occur they generally take the form of narrow fissures resulting from the displacement of large blocks of rock. The Kinderlow Cavern on the western edge of Kinderscout is of this type, where a large but narrow block of gritstone has slipped from the main mass, yet still leans upon it, so forming a roof. The Kittycross Cave in Bradwell Dale, though primarily a limestone cave, is partly developed in decomposed toadstone.

In the limestone area it is important to distinguish between natural caves on the one hand and the underground passages and chambers resulting from lead-mining operations on the other, although the latter have often been the means of revealing some of the deepest and most impressive of the natural caves. A good example is the Bottomless Pit in the Speedwell Mine at Castleton which is due to the solution of lime-bearing minerals, mostly calcite, surrounding the ore body. Again, in the Blue John Mine and the Treak Cliff Mine the search for lead resulted in the discovery of extensive natural chambers. In fact many of the more intricate caverns now exploited as show-places owe their accessibility to former mine workings.

Fig. 6. Distribution of the principal caves in the Peak District. (Based on G. T. Warwick) (#ulink_d08ca058-c042-56b0-87ea-88722be58d55)

In the Peak District the distribution of caves is by no means haphazard. The majority tend to occur around the margin of the limestone in the neighbourhood of streams which flow on to that rock from the higher gritstone areas around it (Fig. 6, see here (#ulink_14a78743-46af-5f3c-8376-9de256d801b9)). Such streams, on encountering the limestone, have developed considerable underground drainage, the more so since much of the limestone, especially along the northern and western margins, is of the reef type (see here (#ulink_b505daa3-0087-546b-a563-b58f75afad06)), which is relatively pure and highly soluble. Under such conditions there is a marked concentration of caves in particular districts. Of these the Castleton, Bradwell, and Eyam-Middleton districts in the north, the Dove-Manifold area in the south-west and the Matlock-Wirks-worth district in the south-east are the chief. In the interior of the limestone area caves occur along some of the valleys such as the Wye and the Lathkill.

Most of the caves, except some in the Castleton group, are situated on the valley slopes or near the present stream level. High-level caves like the Harborough Cave near Brassington, at over 1,000 feet, are seldom found though they are of interest in indicating that ages have elapsed since the water-table stood at such an altitude and they must therefore be of great antiquity. Eldon Hole and Nettle Pot on opposite flanks of Eldon Hill are the only Derbyshire pot-holes, i.e. caves with a vertical pitch, like Gaping Gill in Yorkshire. Eldon Hole is 120 feet long and about 20 feet wide; it reaches to a depth of over 180 feet where it opens into two distinct caverns. Many of the Peak District caves have yielded significant palaeontological and archaeological remains. Thus, from a fissure in the old Victory Quarry north of Buxton, remains of Pliocene mammalian species, including the sabre-tooth tiger, mastodon and southern elephant were brought to light at the beginning of the present century and rank among the few instances of Pliocene cave-finds in Europe. Numerous relics of primitive Man dating as far back as the Bronze Age and even earlier have been found in such places as the Harborough Cave, Thor’s Cave, Thor’s Fissure and Beeston Tor (St. Bertram’s) Cave. None of these, however, is of such outstanding importance as regards evidence of prehistoric conditions as the famous series of caves in the Magnesian Limestone at Creswell in east Derbyshire well beyond the boundary of the National Park. It is their detailed features, including calcite curtains of varying hue, cavities lined with fluorspar, diverse forms of stalactites and stalagmites and the subterranean streams which give to the caves their popular appeal. The Peak Cavern has been famous for centuries. It is referred to as a “marvel of England” in Henry of Huntingdon’s Historia Anglorum, which was written in the twelfth century. Just as generations ago the Cavern earned a reputation among travellers as one of the wonders of The Peak, so today thousands of people each year are attracted to this and other caves which are exploited as commercial ventures. The caves in this category at present open to the public are the Blue John Mine, the Peak Cavern, the Speedwell Cavern and the Treak Cliff Caverns, all in the neighbourhood of Castleton, the Bagshawe Cavern near Bradwell, Poole’s Cavern at Buxton, the Cumberland, Masson and Rutland Caverns at Matlock Bath, and the Fern Cave and Roman Cave at High Tor, Matlock.