388 PROF. S. H. KEYNOLDS AND DR. A. VATJGHAN ON [Aug. I9II, 



the rocks have been extensively quarried. Besides beds made up 

 almost entirely of crinoidal debris, there are many levels at which 

 deposits of a knoll-like nature can be observed, although the most 

 characteristic features of Waulsortian rocks are apparently absent. 



At Waulsort, the knoll type is magnificently developed, and 

 at Ecaussines there is an equally fine display of the typical x Petit 

 Granit. 



That deposits of this type were rapidly accumulated is clearly 

 shown in fig. 12 (p. 386) by the disproportionate expansion of C T at 

 Burrington and at Waulsort. 



The Dolomite. 



As we pass northwards from Burrington or Dinant, dolomites 

 gradually replace the lower, Petit Granit division, until the whole 

 of C l is represented by dolomite, as in the case of the Grande 

 Dolomie of Namur. The consequent diminution in thickness is 

 strikingly brought out in fig. 12. 



The Visean (C-S, S and D). 



Since we are only concerned here with differences within the 

 Bristol-Dinant Province, there is no need to dwell upon the Visean 

 sequence, for the deposits are remarkably similar at the same levels 

 throughout the Province. There is a diminution in thickness of 

 each zone northwards and eastwards as in the Tournaisian, and 

 doubtless due to the same cause. In D of the South-Western Province, 

 Clisiophyllids are abundant at all points ; in Belgium, however, corals 

 are rare except between Liege and Dinant. (They are, nevertheless, 

 abundant in the North-East of France near Avesnes.) 



[In the foregoing account I have omitted all reference to Vise, 

 at which corals of D species abound ; the Vise limestone is an 

 example of the British Midland type, unique so far as Belgium 

 is concerned ; it rests unconformably upon, or is faulted against, 

 typical Devonian.] 



For comparison with the Bristol-Dinant Province, a vertical 

 section of the Ingleborough sequence is included in fig. 12 (the 

 data were kindly furnished by Mr. Cosmo Johns). This section 

 illustrates the two points in which the North-Western Province 

 differs from the South-Western, namely : — 



(1) The omission of lower zones — here the Tournaisian is wauting. 



(2) The expansion of D — here due to the development of Yoredales. 



1 Prof. H. de Dorlodot, of Louvain University, restricts the term Petit 

 Granit to a deposit made up of large crinoid-fragments embedded in a matrix 

 of smaller fragments, with the further condition that the deposits must be 

 of C x age. I have ventured to use the term in a broader sense, for rocks made 

 up almost entirely of large crinoid-fragments, even though their matrix be in 

 part a fine calcareous mud. 



