102 ME. E. H. WORTH 0>' THE [vol. lxxv r 



The shapes of the inclusions are curious : there is no evidence 

 of any bending, for the bedding-planes are parallel in direction 

 throughout each slab. Evidently the cross-joints shaping the slabs- 

 existed before the aplite was intruded. 



Occasionally a vertical joint-face is met with normal to the 

 length of the dyke, and extending completely across the whole 

 height and width of the quarry-face, passing through aplite and 

 shale alike. Such faces must be subsequent to the intrusion. It 

 is notable that these latter joints are peculiarly liable to be lined 

 with fluorspar ; but, while this lines the aplite face, it is not found 

 on the face of the shale. 



Where the inclusions are smaller or less numerous the total 

 width of the dyke is usually less. 



Xot only does the dyke take up large slabs of the shales, but in 

 the quarry on the south-western bank of the Eedaven it may be 

 seen to have broken off and included in its flow a considerable 

 mass of the 'dark igneous' rock, itself intrusive in the shales ; this- 

 mass is nowhere more than 2 feet thick. In this latter quarry 

 the dyke underlies S.E. at an angle of 73° ; its width, at a point 

 where not more than 1 foot of inclusion is to be found, is 62 feet : 

 the quarry at the present time is some 80 feet deep in rock, with 

 8 feet head above this. 



Where the dyke crosses the West Okement, from point LXXVI, 

 S.E. 20 on the map, to the eastern bank of the river, its direction 

 coincides precisely with the strike of the shales. 



The Petrology of the Meld on Aplite. 



Several analyses of the Meldon aplite have been made : of these 

 the two best-authenticated are given below : — 



A. B. 



Si0 o -. 70-97 \n.tn 



TiO; 0-08 J' 1UI 



A1,0 3 17-42 16-85 



F e ;0 3 0-22 0-27 



MgO 0-25 0-05 



CaO 1-28 0-87 



K,0 3-11 3-83 



Ka.,0 5-02 4-92 



MnO 0-28 n.d. 



P,0 5 : 0-03 n.d. 



S6/ 0-04 n.d. 



F 0-08 n. d. 



Li,0 0-004 n.d. 



B/O, n.d. n.d. 



CO.,' n.d. n. d. 



Loss when calcined over 109° C. ... 0'95 1'87 



Totals 99-73 99'73 



A. Analysis for commercial purposes, made by Mr. Bernard Moore,. 



November, 1909. 



B. Analysis made under the direction of Prof. P. G. H. Bcswell, for 



the Ministry of Munitions, 1918. 



