1865.] Hunt on British Gold. 639 



alternate parallel beds of igneous and sedimentary rocks, traversed by 

 mineral veins and trap dykes. A valuable paper on this subject will 

 be found in the ' Transactions of the Geological Society of London,' 

 to which we must acknowledge our debt for much of the geological 

 information contained in this article.* The geological relations, 

 according to this excellent authority, are as follows : — On the north and 

 west of the lower part of the river Mawddach lie the lower part of 

 the Lingula flags and the Cambrian rocks. The latter consist of the 

 coarse, thick-bedded, greenish-grey grits of Barmouth and Harlech. 

 Their upper boundary is marked by a sinuous line, which strikes in a 

 north-easterly direction from Barmouth to Rhaiadr-Mawddach, and 

 from thence trends northerly a little east of Transfynydd to the turn- 

 pike road, about a mile south of Festiniog. The line then strikes S.W. 

 to Morfa Harlech on the coast of Cardigan Bay. These grits are 

 overlaid by that part of the lower Silurian rocks, known as the 

 Lingula flags, which here consist mostly of blue slaty beds, generally 

 more or less arenaceous, and partly interstratified with courses of 

 sandstone. A well-marked portion of the series, composed of rusty 

 ferruginous slate, occupies part of the cliffs of Moel Cynwch, that 

 overhang Dol-fawr on the Maddach. Both Cambrian and Silurian 

 rocks have been penetrated by numerous greenstone dykes, some of 

 which are magnetic. The following exact description of the metalli- 

 ferous district is preserved in Professor Ramsay's own words : — 



" Several lodes occur in this country in the neighbourhood of Dol-y- 

 frwynog and Cwmheisian. The gold at Cwmheisian was discovered in 

 1843 by Mr. Arthur Dean, who, in a paper published in the ' Report of the 

 British Association for 1844," also stated, 'that a complete system of auri- 

 ferous veins exists throughout the whole of the Snowdonian or lower 

 Silurian formations of North Wales.' Recent events would seem, in a 

 slight degree, to verify this bold assertion ; but from that date to this 

 time no one has heretofore attempted to work any mines in North Wales 

 for gold, except that at Cwmheisian ; nor have I ever met with any miner 

 who has seen any gold of the alleged auriferous veins, with many of which 

 1 am also well acquainted. Cwmheisian has been worked several times, but, 

 I believe, never with a steady profit. The gold is found in a branching lode, 

 containing quartz with some iron pyrites. Its principal branch runs north- 

 easterly, and is mostly composed of exceedingly hard quartz, which crosses 

 the river about half-a-mile above Rhaiadr Mawddach. Another quartz lode, 

 bearing lead, occurs a little above the waterfall. A north-west lead lode lies 

 a little west of Moel-Hafod-Owen ; and two others (one of them bearing 

 silver) cross the river in the same direction, about half-a-mile below the 

 fall. They pass through arenaceous slates and greenstone. Two north 

 and south copper lodes cross the little valley that lies between Moel-Hafod- 

 Owen and the hills behind Dol-y-frwynog. Two others occur on the steep 

 slopes that overhang Afon-wen on the west, about half-a-mile south of 

 Dol-y-frwynog. These four are in the talcose rocks above described. 

 Several large quartz lodes traverse this country on Moel-Hafod-Owen. 

 They are in the ordinary Lingula flags. The largest is on the east flank of 

 the hill. The rocks are there much disturbed and altered, and numerous 

 little bosses of greenstone are abundant among its beds. 



* ' On the Geology of the Gold-bearing District of Merionethshire, North 

 Wales. By Professor A. 0. Ramsay, F.R.S. 



