Reviews—Agricultural Geology. 2383 
and little exploitation has been done. On the other hand, calcareous 
deposits of many kinds are widely distributed in the Cape Province, 
except in the extreme east. They are of many ages, ranging from pre- 
Cambrian to Tertiary and Recent, and therefore comprise many 
different types. They are, however, not abundant in the widely 
spread Cape and Karroo systems. The Orange Free State possesses 
abundant resources, especially of surface limestones, an extremely 
interesting rock type which is widely spread in South Africa, 
appearing to be due to evaporation of calcareous solutions ascending 
by capillarity from lime-bearing rocks undergoing decomposition 
below ground. Its origin is therefore analogous to that of the still 
more remarkable surface quartzites of that country. 
The work of compiling this memoir has been carried out with 
great care, and it contains a large amount of valuable and interesting 
information. 
AGRICULTURAL GEoLocy. By F. V. Emerson, Ph.D. pp. xvii + 
319, with 270 figures. New York: John Wiley & Sons, Inc. ; 
London: Chapman & Hail, Ltd. 1920. Price 16s. 6d. net. 
HE late Professor Emerson, whose untimely death is much 
lamented, was Professor of Geology at the Louisiana State 
University, and also in charge of the geological side of the work of 
the State Experiment Station. This book is the fruit of his experience 
in teaching geology to agricultural students. It begins with 
the general characters of minerals and rocks, then passes on to the 
detailed consideration of weathering in all its forms, the action of 
water in erosion, transport, and deposition, and alluvial deposits, 
with a very full account of glaciation and the formation of lakes. 
The characters of coastal plains are discussed, while the final chapters 
deal with mineral fertilizers, the soil regions of the United States 
and historical geology; the last is compressed into less than six 
pages, and might well have been omitted, as the value of so brief 
a sketch as this is problematical. As might be expected, the treat- 
ment of the subject is distinctively American, hardly any reference 
being found to types of soil outside of the United States, although 
very brief accounts are given of the Stassfurt potash deposits and of 
the Chilean nitrate of soda. The middle chapters of the beok, quite 
apart from their value as a treatise on the origin of the soil, form a 
very interesting small textbook of American physical geology, 
and they are illustrated by a large number of good figures, many of 
which, however, are reproduced on too small a scale to be.as effective 
as they deserve. The processes of conversion of rock into soil are 
well described and illustrated by some very well-contrived diagrams. 
SKANES DALMANITESSKIFFER, EN STRANDBILDNING. By G. 
TRoEDSSoN. Geol. Foren. Forh., vol. xlu, 1920. pp. 265-90. 
HE Dalmanites shales of Scania, formerly called the Brachiopod 
shales, are the local representative of the Ashgilhan series. 
The chief object of this memoir is to show that they belong to a 
