Reviews—The Mineral Resources of Great Britain. 281 
steel for munition purposes led to a great expansion of iron-mining, 
especially in the midland counties, the largest producers being the 
Frodingham district in North Lincolnshire, the Marlstone ores of the 
Banbury region, and the Northamptonshire ironstone of the Inferior 
Oolite. All of these are quarried almost exclusively in open-cast 
workings, and the general introduction of mechanical operation did 
much to counteract the labour difficulties that so greatly hampered 
the underground mining in Cleveland. By an elaborate and effective 
system of control, the Ministry of Munitions were able to arrange 
for the regular delivery at the furnaces of mixtures of ore from 
different sources adapted to the production of the types of iron and 
steel most required at the time. The history of this organization has 
been admirably written by Dr. Hatch in a publication reviewed in 
these columns some months ago. 
The memoir now under review contains a very detailed 
and remarkably clear account of the geological relations and 
character of the deposits found in each district, containing a summary 
of all the information available, with abundant references to the 
earlier literature and illustrated by a great number of analyses 
or ores, both of ancient and modern date. There are also many 
tables of production and estimates of reserves. Not only are the 
actual workings now in operation described, but much information 
is included as to areas where ironstone was formerly worked and 
occurrences of ironstone, not hitherto exploited, which may be of 
value in the future. It must be confessed that the latter class do 
not seem to be of much promise, at any rate, until a very radical 
change takes place in economic conditions. 
With regard to the interesting question of the origin of oolitic 
ironstones not very much is said, but the authors, as well as 
Sir A. Strahan in the preface, seem to incline towards the replace- 
ment theory. This is a difficult subject, and cannot be discussed 
here, but the detailed and careful work of A. O. Hayes on the 
Wabana Iron-ore of Newfoundland, and that of other American 
authors, seems to bring forward a good case for the primary origin 
of, at any rate, the green oolitic ores rich in silicates of iron. It is, 
however, very difficult to see how a rich and varied fauna of ordinary 
marine type managed to flourish in a ferruginous solution strong 
enough to lead to direct precipitation of ferrous silicates, which 
must almost of necessity require reducing conditions and absence 
of free oxygen. In this regard the large shells of Cardinia covered 
with a layer of green silicate found in the lower part of the 
Frodingham ironstone are of much interest. 
We congratulate the late director and the officers of the Geological 
Survey on the completion of this exceedingly valuable series of 
monographs on the iron-ore resources of this country. 
Ry EAR: 
