Reviews — Elements of Engineering Geology. 181 



shallow depression surrounded by granite ridges. The junctiou 

 between the syenite and granite can be fixed to within 100 yards or 

 so except to the north, where it is covered by quartz-laterite, whose 

 appearance is taken as approximating to the hidden junction. 

 The intrusion is remarkable for the occurrence of a great limestone 

 inclusion, the actual contact between the nepheline-syenite and the 

 limestone being, unfortunately, hidden. 



The rocks comprising the stock are all nepheline-syenites, ranging 

 from extremely leucocratic to rather melanocratic, from almost 

 saturated to highly undersaturated varieties. The amount of 

 nepheline varies from being quite subordinate to being Jbhe principal 

 light-coloured mineral, and the same applies to orthoclase and 

 albite. The predominant dark mineral is a soda-bearing pyroxene, 

 ranging from diopside to eegirine. Pale yellow sphene occurs, and 

 apatite is abundant in some varieties. A titaniferous lime-iron 

 garnet and primary calcite are also found. Cancrinite often replaces 

 nepheline. Iron oxides and pyrites are extremely rare. 



The author draws up a table showing the " subdivision of the 

 syenoids ", and takes three " ranges ", the foyaite, ijolite, and 

 canadite, characterized by the type of felspar (if any) with the 

 nepheline. These " ranges " are further subdivided according to the 

 percentage of dark minerals present. 



A detailed petrographic description of the varieties of nepheline- 

 syenite found in the area follows, special attention being paid' to the 

 contact facies of the foyaite. 



The limestone xenolith occupies an area of at least '57 square mile, 

 and is a white crystalline marble, showing little sign of contact 

 metamorphism, except recrystallization. In places, however, opal, 

 crocidolite, and apatite, with some granular magnetite, are developed. 



Speculation on the form and nature of the intrusion, and the 

 source and mineralization of the limestone, and its bearing on 

 Daly's hypothesis of the alkaline rocks, followed: by a short 

 description of the economic geology of the area, bring the paper to 

 a conclusion. 



E. S. 



Elements op Engineering Geology. By Kies andr Watson. 

 Published by Chapman & Hall. Price 22s. 



rFHIS is an excellent book, and one that should be included in the 

 -^ library of every engineer. Besides being a good general! text- 

 book on economic geology, the engineer's point of view? prevails 

 throughout. 



The volume is a condensation of Engineering Geology, hy^ the same 

 authors, parts having been re-written and amplified, and' oontains 

 over 250 diagrams and illustrations ; the greater part of: tliese are 

 from actual cases where the geological formations have been the 

 outstanding considerations to the engineer. 



