Vol. xxvii.j ^^^^ Notices. 



235 



explanation as to what it is about. In an equally brief preface 

 the author says that for more than half a century he has been 

 collecting in various countries the material which he has now 

 figured and made available to the general reader, for, after all, 

 the book is not an intricate treatise on geology, but rather a 

 popular explanatory catalogue of objects of Nature's manu- 

 facture. In 1905 Mr. Dunn was awarded the Murchison medal 

 of the Geological Society of London, and he has applied the 

 portion of the fund accompanying the medal towards the 

 production of the work under notice. The definition of a 

 pebble is somewhat difficult, but the author restricts himself 

 to stones or other material from less than six inches in their 

 longest diameter down to stones the size of a pea. The variety 

 of forms assumed is naturally very great, and results from the 

 different materials of which pebbles may be formed, and from 

 the agencies concerned in their making ; thus, heat and cold, 

 wind, water, ice, volcanic action, and other circumstances may 

 have had a hand in the formation of a pebble, and one can 

 quite understand with what interest an enthusiast would pick 

 up a pebble and turn it over and over, and try to imagine its 

 life-history, if such a term may be used. A single stone may 

 represent the work of several agencies. Thus, a certain pebble 

 from the bank of the Orange River, South Africa, if it could 

 speak, would reveal a stor}^ somewhat as follows: — Originally 

 a piece of ancient amygdaloid rock of igneous origin, it w^as 

 rounded by flowing water. Later, a chip was broken off it by 

 glacial action, which also scored and scratched its surface, 

 partly obliterating the sharp edges where the chipping had 

 taken place, but leaving as projections the harder portions, 

 composed of jasper and quartz. Then, when lying in a river- 

 bed, a deposition of other material took place, the river 

 changed its course, it became portion of the Dwyka conglomerate, 

 only to be again released by denudation, and left among its 

 fellows in the Orange River, to be picked up by a Bushman 

 and used as a hammer, finally becoming the plaything of a 

 Dutch boy. 



The plates have been splendidly executed and printed by 

 the D. W. Paterson Co., and, taken merely as typical examples, 

 show what an interesting collection (a collection no museum 

 beetle will destroy) the author must have made during his 

 travels all over Australia, New Zealand, South Africa, Great 

 Britain, &c. The descriptive list of the illustrations adds 

 many details to those already given in the text. Naturally, 

 Victoria offers many examples for figuring, and those who are 

 anxious to take up the study will find numerous specimens in 

 the creeks and gullies of the north-eastern portion of the State ; 

 or, nearer home, the ballast used for the railway line between 



