213 ORDINARY MEETING. JULY 1st, 1881. W. H. HUDLESTON, ESQ., M.A., F.G.S., President, in the chair. The list of donations to the Library since the last meeting was read, and the thanks of the Association returned to the Donors. The following were elected Members :-E. J. Turnbnll, Esq. ; H. Virtue Tebbs, Esq.; A. R. Rayden, Esq.; C. W. Blackman, Esq.; Dr. W. Summerhayes; Rev. E. D. Wells, B.A.; and Miss Agnes Swain. The following Communication was then made :- ON THE GEOLOGY OF THE NEIGHBOURHOOD OF KH:SWICK (WITH REFH:RKNCE TO THE LONG EXCURSION). By W. H. HUDLESTON, M.A., F.G.S., PREIlIDENT. Introduct01,!/.-It has occurred to me that, instead of reading a paper on the geology of this interesting district, I might offer for your consideration a few descriptive notes, and point out some of the more salient featnres which have already occupied the atten­ tion of so many authors. Poets and physicists have been alike attracted by the charms of the English Lakes, and Sedgwick him­ self was one of the earliest to investigate the geology of the region. To say nothing of his numerous contributions to the volumes of the Geological Society on this subject, his letters in Wordsworth's Guide" are still of the deepest interest to the student. In later times the works of Phillips, Harkness, Nicholson, and Ward, have largely contributed to elucidate the somewhat complex and difficult geology of the country, and the latter devoted himself to the geology of the neighbourhood of Keswick, which more especially concerns us this evening. Perhaps at this stage a brief outline of the physical geography of the Lake Country might enable you better to comprehend what I am about to say. For this purpose I would direct your atten­ tion to the Ordnance Survey Map in shaded contours now on the screen. The Lake District, as most of you are aware, is comprised within a somewhat insulated circular area of mountains occupying the south of Cumberland, together with the adjacent parts of * 6th ed., Kendal, 1859. 17 214 W. H. HUDLESTON ON THE GEOLOGY OF North Lancashire and Westmorelalld. The mountains are un­ usually lofty for England, and contain by far the highest summits to be found out of Wales and Scotland. A watershed running nearly east and west, and almost on the parallel of St. Bee's Head, divides the country pretty equally, the waters to the north flowing into the Solway, those to the south in the direction of Morecambe Bay. The northern area, with which we are most concerned this evening, is sub-divided in the £rst instance, by the Helvellyn range, so that the waters flow into the basins of the Eden and Derwent respectively. The Keswick district lies wholly within the latter basin. This almost circular group of mountains consists of three grand divisions of Cambro-Silurian rocks, the lowest and oldest being the SKIDDAW SLATES. The central region is occupied by the VOLCANIO SERIES, and the highest beds are the SILURIANS, that have the Coniston Limestone for their base. Without prejudice, and as a matter of convenience, they might be termed the Lower, Middle, and Upper Silurians respectively. With these are associated cer­ tain granites, "syenites," &c., and the entire group is set in a low frame-work of Carboniferous and Permian rocks. Three moun­ tain masses are conspicuous upon the map: two of these, viz., the Scafell mass and the Helvellyn mass are situated close to the great east and west watershed previously mentioned. Though not actually coincident with the main watershed, these masses, con­ tained entirely within the Volcanic Series and its associated rocks, attract a large rainfall, and must have exercised considerable in­ fluence during the period of Glaciation. The mountains associated with Skiddaw form the third mass. From south by west to north the lowlands of Lancashire and Cumberland intervene between the Lake District and the sea, but on the east a belt of mountainous country, constituting a prolonga­ tion of the main watershed, connects it with the great Pennine Chain of the North of England, formed entirely of Carboniferous rocks. It is across this part of the watershed, in the neighbour­ hood of Shap, that the London and North Western Railway passes from the basin of the Lune into that of the Eden at the moderate elevation of about 800 feet. The line thus skirts the eastern margin of the Lake Country, which presents a strange jumble of peaks as viewed from the windows of the railway carriage. The summit-cutting discloses slaty rock, dipping at a high angle and in THE NEIGHBOURHOOD OF KESWICK. 215 contact with a mass of trap, unconformably overlaid by a red con­ glomerate now regarded as forming the base of the Carboniferous Limestone. The moor is strewn with masses of the celebrated porphyritic granite of Shap, now so largely worked for economic purposes in the neighbourhood of Wasdale, a little to the west of the line. Boulders of this easily identified granite are scattered over the north and east of Yorkshire, and there is a large one at Seamer station close to Scarborough. The run down to Penrith, the Redhill of the North-a fall of about 500ft. in 13 miles-is not long in being accomplished. This portion of the line lies wholly within Carboniferous or Permian rocks. The view across the broad valley of the Eden, bounded on the east by the huge mass of Crossfell-the highest portion of the Pennine Ohain-is very fine. This valley is in the main due to the great Pennine fault. The central portions consist chiefly of Permian sandstones, some of which are rather sterile. Yet a tourist, in summer, would hardly agree with the old saying that " Westmoreland hath much Eden but little Paradise." From the platform of the Penrith station Helvellyn and the mountains about Ullswater are distinctly visible. To Keswick by road tbe distance is 18 miles W.S.W. The railway, owing to the difficulty of gradients, has to adopt a more circuitous route, passing chiefly through the Carboniferous rocks which form the setting of the Lake District proper. Some of the cuttings show sections of boulder clay resting on the Limestone. Not far from Penruddock the summit level is reached, and an excellent view of the moun­ tains in the neighbourhood of Keswick is obtained. But there are two masses in the immediate foreground which will attract our attention. That to the left is Mell Fell, which just appears on the rough enlargement of quarter sheet 101 S.E. of the Geological Survey now placed upon the screen. Tbough only 1,760ft. above the level of tbe sea, its rounded outline at once attracts attention, whilst to the geologist its peculiar situation and internal compo­ sition are both highly suggestive. The hill is part of a remnant of the Basement Conglomerate of the Carboniferous Limestone (Upper Old Red of some), resting quite unconformably partly upon Skiddaw Slates, partly upon the Volcanic Series. This tells a story of two great denudations at different epochs. First of the enormous destruction of the Cambro-Silurian rocks, secondly of an immense removal of post-Silurian deposits, ere tbis hill could 216 ON THE GEOLOGY OF THE NEIGHBOURHOOD OF KESWICK have been fashioned into its present shape. But a still more remarkable fact remains to be told. The materials composing this hill do not consist of trap, or ash, or of Skiddaw Slate, such as occur in the immediate district, but for the most part of grit or micaceous sandstone like some of the Upper Silurians in the southern part of the Lake Country. The bearing of all this on the physical history of the region may again be mentioned. But we must remember that we are on the summit of the Pen­ rith and Keswick Railway, and that the really noble mountain mass in front is the eastern side of Saddleback, 2,847ft., (composed en­ tirely of Skiddaw Slate), which here shows the saddle to great advantage. I have generally considered that this shape was due to 8 synclinal on the mountain top, the left wing of the synclinal dipping to the north-west, whilst the right wing dipped at a less NOTE IN EXPLANATION OF THE ACCOMPANYING SKETCH MAP. Based on the Map in the Survey Memoir, 101, S.E. A. Skiddaw Slates, west of Derwent. A'. Skiddaw Slates, east of Derwent. B. Volcanic Series of the Central region. C. Metamorphic Series of Skiddaw Forest. D. Basement Conglomerate of the Carboniferous System (Mell Fell). E. Volcanic Series of the northern region; a small portion only appears in this quarter sheet. It comprises the remarkable porphyrite of Eycott Hill. N.B.-The strong dark lines represent geological boundary lines. 1. But.termere and Ennerdale " Syenite." 2. St. John's Quartz-felsite. 3. Granite of Sinen Gill. 4. Armboth Dyke-quartz-porphyry. 5. and 6. Similar dykes in the Helvellyn range. a. Skiddaw, 3054feet. b. Helvellyn, 3118feet. c. Pillar of Ennerdale, 2927feet. N.B.-Thel>e three represent the culminating points of the three great mountainous masses, mentioned in the introduction, within the area of the map. Only a small portion of the south-western mass, which cul­ minates in Scafell, 3210feet, and of which the ridge of Pillar forms one of the radii, is seen in this quartersheet. This mass was the great nursery of the glaciers which descended into Borrowdale. FIG. I.-SKETCH MAP OF THE COUNTRY ROUND KESWICK. ~~.. r'OOQ-...\ ...............) ~~ -: •I .' .. ,I'I' I ......, .... \\l._....... )' \. .\ " ./-;fPj............ J !;I ; " ( ! ..) r- 0°'" \ \.