SCIENCE- G OS SIP. 



where the popular prognostics fail, and it is by 



looking at a weather chart whereon the cyclones 

 ; ad anti-cyclones and their relative positions are set 

 forth that the explanation of the failure is revealed. 

 Moreover, in an ordinary way the isobars are 

 circular, but at times they run in straight lines like 

 a series of railway lines, and it is no unconinion 

 tiling for one storm area to be divided from another 

 by these straight isobars. It is at such times as 

 the.-e that distant sounds are plainly heard, such 

 as those made by railway trains, canal boats, and 

 v.aTerfalls. Disranr objects are also plainly seen, 

 and this unusual audibility and visibiliTy have 

 always been a popular prognostic for bad wearher. 

 As we can understand, the success of this 

 prognostic depends on the fact thaT a cyclone is 



following closely behind what meteorologists call 

 some "straight isobars.*' The cyclone at time>. 

 however, shows a disposition to move in unex- 

 pected directions, or to disperse and fill up : and it 

 is when either of these contingencies happens ThaT 

 The prognosTics fail. Not only, therefore, do The 

 modern methods of dealing wiTh weaTher-problems 

 show how iT is ThaT birds and animals, and such 

 creatures as leeches, provide dependable weather- 

 prognosrics, buT They also show why iT is that they 

 often fail. It is sometimes said ThaT animals prog- 

 nosticate changes in the weather ; but the philo- 

 sophically minded attribute no such power:- :■■ 

 them, and the weather charts and isobaric map:- 

 demonstrate that at best they are but prognostic^ 

 London. S.W., May 1900. 



GEOLOGY ABOUND BARMOUTH. 



By John H. Cooke. F.G.S., F.L.S. 



jjiEW districts offer so many attractions to the 

 -*- geologisT as Merionethshire. The diversity 

 of iTs rocks gives rise to a great variety of land- 

 scape, from the brown moorland enveloped in 

 gorse and heather, enclosuring pastures of the 

 softest and richest verdure, to the wooded heights 

 of Lylfaen and the rugged barrenness of Cader 

 and the Axrans. It is an. ideal region for a holiday, 

 comprising within a small and easily accessible 

 area a rare combination of barbaric wildness and 

 cultivated repose. The region around The Mawddach 

 is undoubtedly the finest in Wales. In pictur- 

 esqueness it rivals the Bosphorus. to which it bears 

 a striking resemblance ; and nothing short of a 

 panoramic view can give any adequate idea of its 

 wonderful variety. In the autumn of 1898 I paid 

 my first visiT to this classic region, and in my 

 intervals of leisure I jotted down a few notes on 

 its geological phenomena. These I have now 

 gathered together and embodied in the following 

 short paper, in the hope that they may prove of 

 some interest to future visitors. 



"Merionethshire consisTs. for the most part, of 

 a broad, oval-shaped mountain boss of coarse 

 quartzose and greenish-grey grits of Cambrian 

 age. Barmouth is situated at the south-western 

 extremity of the boss, and on the line of junction 

 of the Upper Cambrian and the languid beds of 

 the Lower Silurian. The strata of Cambrian age 

 which are exposed in the hillsides overlooking 

 Barmouth consist of an alternating series of coarse 

 and fine grits and purple shales dipping from 50° 

 to 60° E.S.E.. with intrusive masses of quartz 

 porphyries and of greenstone dikes. 



The grits are exceedingly compact, and so coarse 

 that many of the angular fragments of quartz 

 which they enclose measure upwards of a quarter of 

 an inch in diameter. Thev consist eenerallv of 



f ragmental quartz and felspar with an appreciable 

 quantity of greenish chlorite united in a siliceous 

 cement : but they are very variable in constitution 

 and structure within even limited areas. The 

 coarse grits alternate rapidly with conglomeraTes 

 and fine-grained sandstones, these again wirh slates 

 and shales. The conglomeratic masses are irregular 

 and pockety, and seldom exceed 3 feet in depth. On 

 the pathway at the back of Moss Bank, overlooking 

 the Barmouth Morfa. The fine-grained grits and 

 sandstones enclose isolated rounded boulders of 

 coarse grit varying from 1 inch to 18 inches in 

 diameter. The variability of the formation is well 

 shown in this section, and also in a huge boulder 

 which lies on the shore-line immediately opposite 

 the bridge which crosses the railway at Llanaber. 

 The face of the boulder, measuring 3 feet 8 inches 

 in widrh. indicates seven periods of depositions, 

 each of which possesses marked characteristics that 

 differentiate it from the others. 



The Barmouth grits do not afford the fossil- 

 hunter many opportunities, as the only evidences 

 of organic life that have hitherto been forthcoming 

 are the tracks and borings of annelids, and, in 

 the direction of Harlech, two species of Oldliamia. 

 The petrographer, however, will find the strata full 

 of interesting points and problems. Two species 

 of felspar occur in the rocks in considerable 

 masses, while the quartz exhibits well-defined, 

 hair -like crystals of rutile as well as liquid cavities 

 containing bubbles. A vein of auriferous quartz 

 dipping 50° E.S.E., and attaining 3 feet in thick- 

 ness, passes through Cellf echan Farm at Barmouth. 

 but though it has been worked .for some years it 

 barely pays its way. The manganese mines on the 

 slopes around the new church at Barmouth are 

 well worth a visit. The grits at this point have 

 been contorted, and one of the mines has been 



