200 



KNOWLEDGE. 



[September, 1901. 



a, man ; and small chance of succour from Murlough or 

 Ballycastle comes that way. The absence of small 

 stones makes the Fair Head talus in certain places 

 almost gruesome ; the fissures widen out into caverns, 

 which have no true floors, but from which one might 

 slip, down the face of one stone or another, till the 

 earliest and lowest layer of the mighty pile was readied. 

 Fortunately, the sharpness of the edges and the angles 

 prevents movement of the blocks themselves; a rocking 

 stone is scarcely met with, and foothold on the 

 crystalline dolerite is secure. 



At one point, a huge mass of columns has slid down 

 the cliff-face without serious fracture, and remains 

 2iropped up against its j)arent, a giant's step to the 

 summit of the wall. Below it is one of the roughest 

 streams of debrix; then again an easier interval, witli 

 tufts of grass and moss, forming bridges that are often 

 serviceable enough. Again and again an ordinary 

 mortal has to let himself down over a joint^face by his 

 arms, to find a foothold on the angle of some lower 

 stone, and then to climb out on the opposite side, like 

 a spirit escaping from a tomb. 



All this is no doubt exhilarating, but equally 

 laborious ; on this winter's day, despite the superb cleai' 

 leather, I confess that I was content to fail. I had 

 thought of gaining the grassy paths of the old collieries 

 in Murlough Bay, and returning serenely by the Bally- 

 castle road ; but, close against the goal, there runs a 

 deep channel in the talus, with blocks of forbidding 

 bulk upon its southern side. I scrambled up and down, 

 could not see my passage, except into the mysterious 

 and communicating vaults below, and preferred to 

 return over the way already known. The strange 

 character of the talus was demonstrated by the fact that 

 again and again one crosses a piece of broken ground 

 by the same stones or the same gaps that have been 

 selected on the oiitwai'd way. The choice on the return 

 journey is limited by the fact that there is often one 

 passage, and no other. Again I write for the veiy 

 ordinary mortal ,; the talus might seem a Jacob's ladder 

 to a cragsman. 



The landmarks by which progi-ess can be reported are 

 the great erratic stone on the very edge of the cliff, 

 left there during the ice-age. before the crag was carved 

 back to its present line ; this or that conspicuous block, 

 resting freshly on the apex of a grey stream of its pre- 

 decessors : or some feature of the columns on the wall, 

 such as the point where they are undercut, and actually 

 overhang the base. 'The scale of the rocky landscape is 

 so large that one hails the passage of these points in 

 succession, until the last wedged up and projecting pile 

 comes in sight, close against the streamlet from Lough 

 Doo. Even here, there is a climb down to tbe gi-ass- 

 slope before the gi-im masses are forsaken. And thence 

 it seems gentle enough to Ballycastle. 



Murlough Bay. if one should reach it by this route, 

 oi- by the legitimate road across the headland, presents 

 beautiful rock-contrasts, even to the untrained eye. The 

 cliff of chalk, high above the wooded combe, rests on 

 rod Triassic strata; these again have a foundation of 

 old crystalline schists. Above the whole, grey in the 

 north-west, the dolerite crag of Benmore ris-es, as a 

 memorial of the volcanic epoch, to which we owe equally 

 tho high ridge of Slemish, and the mosaic pavement of 

 the Giant's Causeway. Along this coast, the form of 

 Fair Head perpetually haunts us; some artist should 

 record it m a hundred aspects, as Hokusai painted 

 Fujiyama. 



THE RINGED PLAINS OF THE MARE NUBIUM. 



By E. Walter M.vundek, f.u.a.s. 



The accompanying photograph was taken by MM. 

 Lcewy and Puiseux at the Paris Obsei-vatory on 1896, 

 September 29. A portion of this same region — the 

 western shores of the Mare Hnmorum — was giveii in 

 the December number of Knowledge for 1899, under 

 the title of " Hippalus and its Siuroundings," and was 

 ail enlargement from a photograph taken at the same 

 observatoi-y on 1896, April 23. In the earlier paper, 

 attention was chiefly drawn to the deep clefts in the 

 mountainous region west of the Mare Humonim, which 

 follow the outline of the sea itself ; to the bold ridges 

 in the sea, which are roughly jiaiallel to both the clefts ; 

 to the border of the Mnre, and to the ramparts — broken 

 down or completely submerged on the seaward side — of 

 the walled plains that are set round the Mare 

 Ilumorum. 



The present plate covers a much wider area. 

 Stretching along its south is a very mountainous and 

 disturbed i-egion, where great ringed plains and rough 

 congeries of unsliapen hills seem at some early dat« to 

 have striven together for supremacj', and where both, 

 indifferently, ai-e now pockmarked by the small deep 

 craters of later convulsions.. Hainzel is half out of the 

 picture. Heinsius, almost eaten up by its three 

 parasitic craters, is on the border to the west. The 

 giant triplet of Pitatus. Gauricus and Wurzelbauer are 

 almost on the terminator, and Capuanus, Ranisden, 

 Mercator and Campanus lie in the southern centre. 



To the east and north-east are the Mare Humoriun 

 and the Oceanus Procellarum. The first is not well 

 seen on this photograph owing to the conditions of the 

 exposure and development, but the huge walled plain, 

 Gassendi, on its northern shore, is very well shown, and 

 the highlands which extend from it to the borders of 

 the ruined plain Letronne. - 



The whole centre of the photograph isxoccupied by 

 the Sea of Clouds,-, and its floor jJi'esents a study of 

 walled and ringed plains, in all states of preservation 

 and decay. Bullialdus. the gi-eatest and deepest of 

 those on the floor of the sea. seems also to be of the 

 most recent date, and from its south-west, border there 

 comes a curved chain of four craters, Bulliildus A. B. C, 

 and Agatharchides A, t.he largest craters in the Matf. 



To the north, Liibiniezky is evidently much more 

 antique, and its ramparts are weathered to a smooth 

 round cui-ve ; its floor is flattened to a dead level, and 

 neither Schrbter, Miidler nor Schmidt ha.ve been able 

 ever to detect any irregularities upon it. In the photo- 

 graph, the wall has a distinctly horse-shoe aj)i5earancc 

 with the opening to the south-west, but Neisoii draws 

 a continuous ring, as distinct, on the south-west as on 

 the north-east. Close examination of the photograph 

 .shows that the wall is continued right round, fovu- 

 buttresses apparently blocking the entrance to the 

 horse-shoe. 



In a much worse state of "Jjreservation is Fra Maiiro, 

 which lies further to the north-west and almost on the 

 terminator. At some places its wall is very much 

 defaced, in others quite broken down. In its eastern 

 border, there is a deep irregular depression which is 

 continued towards the north through the highlands and 

 the low-lying counti-y beyond, as far as to the east of 

 Gambart A ; and cutting the ringed plain of Fra Mauro 

 in two and passing through its central craterlet, is a 

 veiy delicate; and line rill which Ncison traces from the 



