428 Reviews — Geology of the Mid-Continental Oilfields. 



gravels, and clays overlying it, and certain deposits of the 100 foot 

 terrace, with peat and other recent formations. Some of these are 

 of economic value for brick-clays, moulding and furnace sands, 

 and other j^urposes. 



The Geology of the Mid-Continental Oilfields. By T. 0. 

 BoswoRTH, D.Sc, M.A., F.G.S., F.R.G.S. pp. xii + 314. 

 New York : The Macmillan Company. 1920. 

 "PkR. BOSWORTH has provided in this volume a most useful 

 -*-^ addition to oil-field literature. It is in the main an epitome 

 of the voluminous and detailed work which has been carried out 

 in this area by the United States Geological Survey and other 

 workers. It is no light task, even if one has access to the 

 numerous American publications, to abstract from them the 

 specific information required, and it is this task which the author 

 has taken in hand, and he has shown a wise discrimination in 

 selecting from the vast amount of detail available the salient 

 points to form a general, yet in certain respects detailed, summary 

 of the whole. 



The material is on the whole well arranged, though perhaps it 

 might be said to suffer from over-classification. The book is 

 divided into " parts ", " chapters ", and " sections ", and 

 especially in the later portion of the book there is a quite needless 

 multiplicity of chapters, while the headlines throughout are rather 

 reminiscent of the American press. 



The work is supplemented by a very full bibliography (chap, ii), 

 and numerous references throughout the text. Part iii gives 

 an account of the vigorous development of the field which brought 

 it from its modest production prior to 1903 to its present position 

 of producing nearly one-third of the world's annual oil output, 

 and is of especial interest at the present time when so much is 

 being written on the world's supply of oil and America's present 

 and future position. 



The text throughout is well supplemented with plans, geological 

 sections, tables, etc., together with a number of photographs. 

 The author first discusses the general structure and stratigraphy 

 of the region, and then gives in parts vi and vii a more detailed 

 account of the local characteristics of the different fields. Parts ix 

 and X give an account of natural gas and its relation to the dis- 

 tribution of oil, together with an outline of the methods employed 

 for the recovery of " gas gasoline ", a process rapidly increasing 

 in economic importance with the ever-increasing demand for 

 light spirit. The subject of helium is dealt with, a matter of which, 

 owing to the activities of the censor, we heard little at the 

 time of its discovery in commercial quantities in 1917, but one 

 which, had the supplies of gas been mid-European instead of 

 mid-Continental, would more than probably have been brought 

 forcibly to our notice. 



