7G 
PROCEEDINGS OF SOCIETIES. 
Sir Roderick Murchison, though not with us corporally, has sent 
us a valuable paper on the crystalline rocks of the H. W. Highlands, 
which he proves on fossil evidence to be of lower Silurian age. 
Professor Harkness continues his observations on the triassic forma¬ 
tion of the south of Scotland and H, W. of England, which appears to 
harmonize more with the continental deposits than any other within 
these isles. He also read papers on the lower sedimentary rocks of 
Cumberland, and on the dolomitization of rocks in the vicinity of Cork. 
Professor Phillips gave us one of his graphic sketches of the iron¬ 
stone beds of the Glites of Yorkshire. 
Professor W. B. Bogers exhibited some good photographs of that 
peculiar and characteristic Palaeozoic fossil, the Paradoxides. 
I beg to call your particular attention to our member, Mr. Robert 
Mallet’s ‘ ‘ Report on Earthquakes.’ ’ He has for many years studied these 
phenomena, and explained them by those great cosmical theories to which 
the powers of analysis and pure mathematics have been so successfully 
applied. We must all rejoice to hear that he has been dispatched, under 
the sanction of the Royal Society, to inquire into the circumstances 
attending the almost unexampled physical disturbances in Southern 
Italy. 
Another great question in Physical Geology, the subject of slaty 
cleavage, has also been well discussed. Professor Sedgwick and Mr. 
Sharpe have long since propounded theories to explain these properties 
of rocks. But it is only within a recent period that the Baconian system 
of induction has been systematically brought into action in order to 
afford a rational solution of them. Mr. Sorby has most minutely ex¬ 
amined slaty rocks under a powerful microscope of 400 linear, and he 
comes to the conclusion that pressure in a direction perpendicular to the 
direction of the cleavage planes is sufficient to account for these pro¬ 
blems. He observes:—“In cleaved rocks, whether we examine the 
diminution in distance between any two points lying in the line of 
pressure in contorted beds, the dimensions of the beds in different parts 
of contortions, the organic remains, the green spots, or the very minute 
rounded grains of mica, we find most conclusive evidence of an elonga¬ 
tion in the line of dip of cleavage, and of a great compression invariably 
in a line perpendicular to the cleavage.” 
Professor King has also confirmed this view by comparison with the 
views observed in crystallized minerals. 
Professor Haughton also has come to a similar conclusion, by a 
study of the distortion to which fossils are so frequently liable in slaty 
rocks; he has accurately measured the angles which they form to the 
planes of cleavage, and has thence deduced the following laws:— 
1st Law.—If the trace or intersection of the plane of cleavage and 
plane of bedding be drawn, the greatest distortion or elongation of the 
fossils lying in the plane of bedding is parallel to this intersection. 
2nd Law.—The distortion of fossils produced by cleavage, estimated 
in a given direction, such as parallel to the intersection of the planes of 
cleavage and bedding, varies with the angle between these planes, being 
greatest when the angle is greatest, and least when the angle is least. 
