82 PKOCEEDINGS OE THE GEOLOGICAL SOCIETY. [May 1 894, 



a part of the northern slope of the Berwyn Hills stretching along 

 the southern bank of the Dee. The stratigraphy of this slope is 

 worked out with much care. No fossils have as yet been found in 

 the Corwen Grit, but there is a grit at Glyn Ceiriog, occupying a 

 similar position, which has yielded many. The Authors conclude 

 that the Corwen Grit clearly forms the base of the Llandovery in 

 this area, whilst between it and the Tarannon Beds are black shales 

 containing numerous graptolites of the Monograptus gregarius-zone. 

 Their researches were still insufficient to show whether Upper Bala 

 rocks are absent or not from the region, though the evidence at 

 Corwen itself seemed distinctly in favour of a break. 



Cambrian. — We are now approaching the lower limits of the 

 palaeontological column, and there is a corresponding difficulty in 

 the arrangement of the subjects, owing to the existence of beds 

 which some authors regard as Cambrian and others as pre- 

 Cambrian. So long as there are any remains of a fauna to guide 

 us we are on tolerably safe ground, and it thus seems advisable to 

 separate papers which contain references to palaeontological evidence 

 from those entirely based on stratigraphy and petrology. Under 

 the description of palaeontological evidence one would be disposed to 

 exclude for present purposes most of those enigmatical markings 

 which have been noted, from time to time, in beds presumably 

 underlying the fossiliferous Cambrians. Such beds may ultimately 

 yield to research a distinctive fauna, but at present they must be 

 regarded as mere aspirants to rank in the palaeontological column, 

 and are for that reason best placed in the category of ' Fundamental 

 Rocks.' An exception may be made in the case of the Pipe-rock of 

 Assynt, which, although below the lowest recognized Cambrian fauna, 

 must certainly be included with that system, and this also may carry, 

 as hinted by Prof. Sollas, certain rocks in the neighbourhood of 

 Dublin which were once claimed by Prof. Blake as Upper Monian. 



The papers dealing with the fossiliferous Cambrian are not 

 numerous. If we exclude those which treat of the Longmynd and 

 the volcanic series from a stratigraphical and petrological point 

 of view, there are not more than half a dozen. North "Wales 

 receives notice from Dr. Woodward in his paper on ' Trilobites in 

 the Cambrian green slates of the Penrhyn Quarries.' The papers 

 by Sir J. W. Dawson on the Eozoic and Palaeozoic rocks tff the 

 Atlantic coast of Canada refer to the whole of the Palaeozoic series 

 and include likewise ample notices of the Fundamental Blocks. It 



