/. R. Bakyns — Note on the Green and Skiddaw Slates. 117 



consists of hills of Skiddaw Slates, the eastern side, with the 

 exception of a narrow strip near the water about Lowdore, is com- 

 posed of hills of the volcanic series. Now were the two sets of 

 beds conformable, as they have hitherto been generally considered 

 to be, and as they have always been mapped, this would require a 

 fault along the lake with an enormous throw, which would, doubt- 

 less, highly delight those persons who, having surveyed but little, 

 fancy there are always faults along valleys, especially if the valleys 

 are occupied by lakes. If, however, the two sets of beds are un- 

 conformable, of which I have very little doubt, then the structure of 

 the country is perfectly intelligible, without calling in the aid of a 

 fault, which, however, may exist for aught I know. 



As I have alluded to those theorists who used to explain lakes as 

 lying in open fissures caused by faults, of the existence of which 

 fissures there is not a particle of positive evidence — a race of Geo- 

 logists, which I fear is not yet extinct, though they doubtless 

 received their death-blow in the excellent paper by Professor 

 Eamsay on the origin of lakes — I may as well say that I saw several 

 instances in the Lake Country of lakes lying in true rock basins ; for 

 instance, Thirlmere lies in a rock basin. Again, there can be no 

 doubt, from the great spread of alluvium, that part of Borrowdale 

 above the Bowder Stone was once occupied by a lake as far as 

 Seatoller certainly, which lake probably split into two arms 

 running some way up the two valleys of Stonethwaite and Sea- 

 thwaite. Now this old lake was enclosed in a rock basin, the well 

 glaciated barrier of which crosses the valley a little south of the 

 Bowder Stone and blocks it up, save where the stream has cut a 

 narrow channel for itself. 



The gradual silting up of the lakes is also well exhibited in many 

 of the still existing lakes. Derwentwater and Bassenthwaite are 

 separated by a wide, low alluvial flat, but little higher than the 

 levels of the lakes, which doubtless once formed one great lake 

 reaching as far as Grange. Similarly, Buttermere and Crummock 

 once formed one lake, which reached more than half a mile higher up 

 the valley. 



IsTOTIOIES OIF DVCEnyilOH^S. 



Transactions of the Manchester Geological Society. Vol. vii., 

 Part 9, and Vol. viii., Part 1. 1868. 



PAET ix. contains a paper by Mr. P. S. Eeid, on some copper, iron, 

 and other mineral deposits of the Maritime Alps, in the districts 

 of St. Sauveur, Valdeblore, and St. Martin de Lantosque. 



The mines of St. Sauveur and Valdeblore are situated on the 

 French and Italian frontier, about 35 miles from the town of Nice. 



The predominant formation is Jurassic Limestone, under which 

 and reposing on Mica Schists are metamorphic rocks, answering in a 

 great measure to our New Ked Sandstone formation, and in these 

 the principal deposits of copper, now described, are found. 



