Storms of More Or Less Violence Occurred in Many Parts of the British Isles on June 3Rd, 1908

Downloaded from http://pygs.lyellcollection.org/ at University of St Andrews on June 15, 2015 383 SOME EFFECTS OF THE STORM OF JUNE 3RD, 1908, ON BARBED FELL. BY ALBERT CILLIGAN, B.Sc. (Read \2ih November, 1908. MS. received 30tk November, 1908.) Storms of more or less violence occurred in many parts of the British Isles on June 3rd, 1908. The West of Yorkshire seems to have been unfortunate in being the neighbourhood where the greatest downpour of rain took place, and conse• quently suffered more destruction than any other district. The stretch of country affected by the storm extends from Airedale to Swaledale, embracing in its path four watersheds. Much havoc was wrought throughout the whole area, but the special district with which it is proposed to deal is that of Barden Fell. The highest point of the hill, near the Upper Barden Reservoir, is 1,661 feet above sea level. The hill is drained normally by a number of becks, which flow radially from its summit, the chief of which are Barden Beck and Gill Beck on the east ; Loburn Gill and Moor Beck, which join to form Embsay Beck, on the south ; while on the west there are Fell Gill, Waterfall Gill, and Red Gill, tributaries of Eller Beck (see Map, Fig. 1). These streams all run down scarp slopes of the Kinderscout Grit, of which the hill is composed, and have in consequence deep narrow channels, with many waterfalls, where they have encountered the beds of shale which are interbedded with the grit. I visited the district in the neighbourhood of Burnsall a few days after the storm, and explored the fell side, which is in the occupation of Mr. Thompson, Wood End Farm. In the field below the main road from Bolton Abbey to Bumsall deep trendies had been cut, and some of the solid grit removed. The field was strewn with blocks of grit, and the wall bounding the field on the lower side had been breached in two places (Plate LV., Fig. 1). Following the track of the torrent up the fell side, it was found that the main road had been ploughed Downloaded from http://pygs.lyellcollection.org/ at University of St Andrews on June 15, 2015 384 GTLLTGAN : EFFECTS OF STORM ON BARDEN FELL. Fig. 1. MAP OF PORTION OF THE AREA AFFECTED BY THE STORM. REPRODUCED FROM THE 1 INCH ORDNANCE MAP. {With ilie sanction of the Controller of H.M. Stationery OJlce.) Downloaded from http://pygs.lyellcollection.org/ at University of St Andrews on June 15, 2015 GILLIGAN : EFFECTS OF STORM ON BARD EN FELL. 385 itp to a depth of six feet, and the walls on either side thrown down, leaving gaps about twenty feet wide. The height at which the water had stood at the fell side cf the top wall was easily traceable by reason of the bracken and grass infilling the chinks. This height varied from eighteen inches to three feet six inches, according to the lie of the ground. The water crossed the road at a point where the ground rises to a crest in the line of the new channel. In this new channel was found remarkable evidence of the cutting power of a mountain torrent. Careful measurements showed that in many places the solid grit had been removed to a depth of twenty feet, while the greatest width was twelve feet. The deepest holes were always found succeeding a place where the water had been imprisoned in a narrow channel, and the material scooped out of the hole has been piled up on the lower side to form a boulder bar. '; Scape-colks " similar in their mode of origin, i.e., con• striction of the water channel, have been described by Suess* as occurring in the bed of the Danube during the construction of dams for the purpose of diverting the river. Much of the rock in this part of the channel is crushed, as by faulting, and a vein was found at one part, but a search failed to reveal any metalliferous ore, though on the other side of the valley of the Wharfe the veins in the limestone bear galena, which has long been worked. It seemed at first as if the course of the stream had been determined by a pre-existing channel along a line of fault, but I was assured by those in the neighbourhood who knew the ground thoroughly that no channel had existed there prior to this storm. Another interesting feature, which was noticed both in this channel and at most other places round the fell, was that a stiff boulder clay, containing limestone pebbles, which covered the ground, had offered a powerful resistance to the cutting action of the current, and had preserved the underlying rock. The wall separating this field from the rock-strewn fell above had, in common with others, been breached, and afforded evidence of previous storms, not so violent perhaps as the present one, but nevertheless bringing down much material from the higher * Suess, "The Faoe of the Earth," Vol. II., p. 343. Downloaded from http://pygs.lyellcollection.org/ at University of St Andrews on June 15, 2015 386 GILLIGAN : EFFECTS OF STOSM ON BAEDEN FELL. part of the fell. The old foundations of the wall could be seen six feet below the present level of the ground, and stratified gravel, alternating with beds of peaty mud and angular pieces of grit, were exposed where the wall had been washed away (Plate LV., Fig. 2). This wall had fortunately determined the course of one of the tributary streams along the top of Thomp• son's Folly Plantation, or the farm which lies directly below might have been swept away. In the channel cut by this tributary stream evidence of the forces bringing about the folding and faulting of the whole district could be seen in the beds forming an unsymmetrical anticline, which had passed over into a reversed fault on the other side of the channel. Striking north-west across the fell two old channels were found, now quite dry and unaffected by the storm, which were probably the drainage channels of some previous storm, and helping to confirm the observations made regarding the stratified deposits near the wall. Another channel only fifty \ ards further on was one of the main drainage channels of the recent storm. The amount of material cut out of its bed was enormous, and has been spread out in a fan some distance below. In nearly all cases the cutting in the smaller channels branching from the larger ones commenced quite suddenly, due no doubt to the cutting back of the waterfalls formed by the rapid deepening of the main channels, each of the waterfalls having the usual boulder bar. A portion of one of these new channels is shown in Plate LVL, Fig. 1. An old cart-road leading up to a quarry on the fell side had during the first part of the storm formed an easy escape for the water, but as the volume increased the water could not follow the windings of the road, and burst through the sides at the sharp turns, just as rivers cut a shorter channel and leave the " ox-bow " channels on their sides as records of their former courses. To the north of this road a fault which runs south-west to north-east, and throws the Millstone Grit against the Pendlesides, has been well exposed, and some interesting points which need more careful study have been disclosed along this fault line. It seemed at first nothing more than a normal fault, but an Downloaded from http://pygs.lyellcollection.org/ at University of St Andrews on June 15, 2015 GDLLIGAN : EFFECTS OF STORM ON BARD EN FELL. 387 examination of the shales in the grit showed evidence of much crumpling, in one place, at least, the beds being vertical. The grit along the line of fault is much crushed, and has wisps of Pendleside shale caught up in it. Furthermore, the Pendle• sides here show beautiful slickensiding along horizontal planes. Confirmation of what appears to be thrusting is found again lower down the fell side, where the beds are inclined 45° in the direction N. 60° W., and appear to have been packed up over the beds below, which are nearly horizontal. The direction of •dip here is almost at right angles to the dip found near the fault in the shales of the grit series, and without very careful map• ping it is difficult to see clearly what has taken place here, but the evidence seems to point to thrusting in a direction from north-west to south-east. Gill Beck.-—The lower part of this beck was swept quite clean to the rock floor, and at the new bridge only a few very large boulders had been left behind. Higher up the beck the debris had completely choked the channel, being piled up at a point where the course of the beck takes a sharp turn. A waterfall in Nelly Park Wood had been cut back about ten feet, and a well-defined fault clearly shown. The weirs con• structed by the Bradford Corporation had been much damaged, several of the huge blocks of grit forming the aprons of the weirs having been displaced, and the residuum lodge near Gill Beck Head completely filled with sand. Barden Beck.— This was the main channel for the water, which rose at least ten feet, as shown by the grass still clinging to the trees up to that height.

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