Reports & Proceedings — Liverpool Geological Society. 231 



on the same lines in the same manner, and are connected by 

 continuous lines. Not only will this diagram indicate the pro- 

 portions of the constituents, but also the position of the points 

 on line (4) relative to those on lines (2) and (3) will indicate 

 the probability of the occurrence of minerals dependent on 

 the amount of alumina. If (4) is higher than (3), andalusite, 

 cordierite, or mica may be expected as well as hypersthene, all the 

 lime being converted into anorthite. If (4) is less than (3), diopside, 

 auy;ite, or the corresponding amphiboles will probably be present ; 

 and if it is less than (2), minerals of the segirine type may be found. 

 In the second or silica diagrams the lowest series of points show the 

 amount of silica required by the bases of a rock for the formation of 

 leucite, nepheline, anorthite, woUastonite, and olivine, the second 

 series the additional silica necessary to form orthoclase and albite, 

 and the third series the amount required to convert the olivine into 

 hypersthene, while the fourth line represents the amount of silica 

 actually present. The position of the last relative to the others will 

 throw valuable liglit on the silicates that may be expected, though 

 allowance must be made for the influence of the bases on one 

 another. For instance, the presence of the constituents of 

 woUastonite will call for a higher silicification of part of the olivine 

 to form a monoclinic pyroxene or amphibole at the expense of the 

 felspars. 



III. ^Liverpool Geological SociETr. 

 Ilarch 12, 1918.— J. C. M. Goveir, M.D,, M.H.C.P., F.G.S., 

 President, in the Chair. 

 The following papers were read : — 



1. "On the Distribution and Significance of Barium Compounds in 

 Sedimentary Rocks, with special reference to the Trias." By H. W. 

 Greenwood. 



The author had collected a large amount of statistical information 

 as to the presence of barium compounds in the lithosphere, the 

 oceans, and underground waters, which revealed their widespread 

 occurrence, especially in Triassic sandstones in the form of barytes. 

 In the latter it was noted that the barytes is apparently invariably 

 secondary, and has found its way into the rocks by percolation and 

 infiltration, that it occurs in both the Keuper and IBunter divisions, 

 is richest at the surface, the quantity falling rapidly witli the depth, 

 and is commonly most abundant in the highest exposures in any one 

 district. These facts, among others, led the author to suggest that 

 the barium had been derived froin superincumbent strata, most 

 probably Jurassic, a suggestion which, if upheld, would make the 

 presence of barytes a valuable index to the original distribution of 

 the Jurassic seas. 



2. " Notes on the Parallel Roads of Glen Roy." By C. B. Travis. 

 In this paper the author gave an extremely lucid description of 



these well-known natural features, based upon personal observations 

 made during visits within the last few years. 



