R. L. Sherlock — Marine Band in Middle Coal-measures. 311 



in the felsic constituents. Ilmenite is present, but in very small 

 amount. Amongst the predominant felsic or leucocratic minerals 

 nepheline is the most conspicuous. It occurs in well-formed crystals 

 which are euhedral toward analcite and orthoclase, hut not to 

 plagioclase. Orthoclase is more prominent than plagioclase, whilst 

 the latter is highly analcitized. Analcite, with anomalous double 

 refraction, fills up the interspaces. 



Variety 4. — This occurs closely associated with the two preceding 

 varieties in thin streaks or schlieren that have been drawn out 

 together during intrusion. It is chiefly distinguished from variety 3, 

 which it closely resembles otherwise, by its much finer grain. 

 Barkevikite is especially prominent in small prisms, and is intergrown 

 in very irregular fashion with titanaugite. This, and the succeeding 

 variety, are little more than textural modifications of varieties 

 2 and 3. 



Variety 5. — This schlier resembles variety 4 in granularity and 

 generally in mineral content, but is devoid of titanaugite. The 

 barkevikite has an acicular habit which makes this a striking and 

 easily recognized type. In the hand-specimens the barkevikite 

 forms numerous black needles embedded in a pinkish groundmass. 

 This rock is rich in nepheline, and in the unknown mineral which 

 resembles and occurs along with the nepheline. The nepheline is 

 well-shaped and is usually crowded with prisms of barkevikite. 

 Analcite occurs in considerable quantity, and orthoclase is dominant 

 over plagioclase. 



Variety 6. — This is a white-spotted rock from the exposure on 

 the west side of the quarry, and is characterized by its richness in 

 small, perfectly euhedral crystals of titanaugite. Barkevikite is 

 in subordinate quantity. The rock is also characterized by containing 

 more or less rounded areas of the felsic minerals, almost completely 

 devoid of the coloured constituents. These appear as white spots 

 in the hand-specimens and slides. Growths of chlorite rosettes 

 occasionally form some proportion of these spots, and probably replace 

 analcite. This rock appears to be a textural modification of variety 2. 

 {To be concluded in August Number.) 



IV. — On a Marine Band in Middle Coal-measures, 



South Lancashire. 



By E. L. Sherlock, D.Sc, A.K.C.S., F.G.S. 



UP to the present marine fossils have been recorded in Middle 

 Coal-measures in the South Lancashire Coal-field at two 

 horizons only. They are (1) in the banks of the Tame, near Ashton- 

 under-Lyne, found by Professor A. H. Green, 1 and at Ash ton Moss 

 Collier v, about 750 feet above the Great Mine, discovered by the late 

 George" Wild. 2 (2) Mr. H. Bolton, P.H.S.E., informs me that the 

 Californian or Thin Bed of Pulledge Colliery, Burnley, which is 

 410 feet above the Arley Mine, is a marine horizon. 



Mr. John Gerrard, in his Presidential Address to the Manchester 

 Geological and Mining Society, 3 mentioned a marine band found at 



1 E. Hull, Geology of the Country around Oldham (Mem. Geol. Surv.), 1864. 



2 J. Gerrard, Trans. Inst. Min. Eng., vol. xxviii, p. 363, 1904. 3 Ibid. 



