I^othsbire flaturalists' lElnion. 



SUPPLEMENT TO CIRCULAR 



oi 136th MEETING, at 



CLAPHAM, 



ON SATURDAY, 14th MAY, 1898. 



GEOLOGY OF BOWLAND KNOTTS.— Mr. R. H. Tiddeman, M.A., 

 F. G.S., writes that the geology which may be met with from Clapham southwards 

 is all contained in the Geological Survey Map, Sheet 92 N.W. (new series Sheet 60) 

 which may be had either coloured for solid rocks only or for drifts as well. The 

 solid rocks edition is the best to get for the geology generally, as so much of the 

 detail is lost in the drift colouring. A horizontal section. No. 147, from Heysham 

 to Settle, also relates to this ground. The distance from the Clapham station to 

 Bowland Knotts is under five miles, a fairly direct mountain road but all against the 

 collar. The ground passed over consists entirely of beds of Millstone Grit and 

 associated shales. These are much broken by a series of faults, which range from 

 W.N.W. to N.N.W. It would be difficult to make out the arrangement of these 

 rocks were it not for the clues afforded by two fairly distinct beds: (l), Black 

 Fossiliferous Shales, containing posidonije in chief abundance, orthoceras, gonia- 

 tites, occasionally fish scales and teeth, and fragments of fossil plants; (2), The 

 sandstone below this is remarkable for being a hard siliceous rock (almost a 

 ganister). A few feet below the top of this there is often a thin bed of coal, 

 which may be found by poking about under the beds of sandstone. It is generally 

 found in a pool in the stream. At a lower level at the bottom of the grit or a little 

 below it, is often a bed of coal of better proportions, ranging about l-ft. lO-in. to 

 2-ft. o-in. This has been extensively worked by level and crop works, not so much 

 here as on the extension of the outcrop westwards towards Lancaster (91 N. E. ). 

 It has been worked near Wray, Hornby, Farleton, and Caton, and in the valley 

 of the Conder, and generally goes by the name of the Caton Coal. Like most of 

 the Millstone Grit coals, it is inconstant in thickness, and often probably absent or 

 reduced to a mere trace. The shales mentioned above may be known on the map 

 by the green colour given them. The geology is not to be plainly seen alcng the 

 road, but Keasden Beck on the west, and Kettlesbeck from i to ij miles east of the 

 road, give very good sections and are pretty little glens, although there are not, 

 so far as I recollect, any footpaths along them. Another smaller and shorter gill 

 which runs down by Throstle Nest and is close to the road, gives a fair exposure 

 of the Fossiliferous Shales, and shows the Coal Grit thrown up by a small fault. 

 At Dovenanter End a small vein of galena was tried many years ago. In Kettles- 

 beck, right bank, between the railway and Kettlesbeck Bridge, a calcareous bed was 

 found containing Prodiictus and Spirifer, a very unusual fauna in these Millstone 

 Grits. This is a higher horizon than that of the Fossiliferous Shales above the 

 Caton Coal Grits. A trace of it was also found in the road as it crosses the hill 

 S.W. of Dubgarth. Drifts. — The peaty flats about Clapham wander about 

 amongst numerous drumlins, old ice-sheet rubbish. The north end of Burn Moor 

 is covered with a spread of drift and here and there little ridges, which are evidently 

 the moraines of dwindling glaciers coasting the fell, present themselves. Occasion- 

 ally Silurian boulders are found here, which probably came from Ingleton, or the 

 other older foundations of the Ingleborough range. Drift is to be found high up 

 on the ascent to Bowland Knotts. Glacial stria; on the rocks, especially on the 

 fine surface of the Coal Grit, are common, and I have found scratched surfaces 

 with overlying boulders on the Knotts themselves. These scratches are striking for 

 Pendle, and show that an ice-stream crossed the ridge at an elevation of about 

 1,400 ft. — (See "Evidence for an Ice-Sheet in N.Lancashire, Yorkshire, and Westmor- 

 land," by R. II. Tiddeman, Quart. Journ. Geol. Soc, pp. 471-491, 1872). 



