44 
Proceedings of the Royal Society of Edinburgh. [Sess. 
IY. — The Origin of Oil-Shale. By E. H. Cunningham-Craig, 
B.A., F.G.S. Communicated by Dr Horne, F.R.S. 
(MS. received December 1, 1915. Read December 20, 1915.) 
CONTENTS. * 
I. Introductory ......... 44 
Definitions and Theories ........ 45 
II. Field Evidence ......... 48 
(a) From Oil-Shale Fields ....... 48 
1. The Lothians ....... 48 
2. South Africa ........ 55 
3. New South Wales ....... 56 
(b) From Oil-Fields . . . ■ . .58 
1. Barbados ...... 63 
2. Trinidad ........ 64 
(c) From New Brunswick ....... 66 
III. Filtration, Absorption, and Adsorption .... 68 
IY. Properties and Composition of Clays . . .73 
V. Ammonium Sulphate ........ 76 
YI. Conclusions ......... 80 
I. Introductory. 
Geologists who have made a special study of petroleum and the conditions 
under which it occurs have not infrequently to deal with the kindred 
subject of oil-shales. These subjects, it is true, have always been considered 
as entirely separate and different, and for all practical purposes they are 
so, since the mining of oil-shale and the drilling for oil have nothing in 
common from the engineering point of view ; yet the final products of the 
distillation of natural petroleum and oil-shale are to some extent identical, 
and it has more than once been suggested that some relation may exist 
between an oil-rock and an oil-shale. 
It is with the idea of reviewing the evidence bearing upon this point 
that this paper has been written ; it must be considered merely as an 
inquiry, dealing chiefly with geological field evidence, as to whether any 
light can be thrown upon the origin of oil-shales by a study of petroleum 
in its broadest and most comprehensive sense. Theoretical disquisitions 
will be disregarded as far as is possible, and only evidence published by 
geological surveys and acknowledged authorities, or gleaned from the 
writer’s personal observations in different parts of the world, will be 
brought forward. 
