PREFACE TO THE SECOND EDITION 



The first edition of Subsurface Geologic Methods, published in June of 

 1949, had a gratifying reception as a textbook for universities offering courses in 

 subsurface geology. Owing to the unexpected rapid depletion of the supply of 

 this volume, it was deemed necessary to revise and enlarge the book as a second 

 edition. 



The first printing of second edition, published in June, 1950, includes sev- 

 eral new sections which are of concern either directly or indirectly to the 

 subsurface geologist. These additions cover the following subjects: secondary- 

 recovery methods, evaluation of petroleum properties, geochemical methods, 

 micrologging, drill-stem testing, mud chemistry, cementing problems, acidiza- 

 tion, shale-density analysis and graphic methods in mining. A series of ques- 

 tions has been added at the termination of each chapter to permit improved 

 instruction in university work. An index has also been included in this volume. 



Grateful acknowledgment is hereby given to the Department of Publica- 

 tions of the Colorado School of Mines for making possible the publication of 

 this volume and to George W. Johnson, Acting Director of Publications, for 

 his efforts and interest in the editing of the present volume and for supervising 

 the numerous engraving and binding problems. 



Special acknowledgment is given to the American Association of Petroleum 

 Geologists for permission to reprint John M. Hills' paper, "Sampling and Ex- 

 amination of Well Cuttings," and to the American Institute of Mining and 

 Metallurgical Engineers for the courtesy of permitting the publication of H. G. 

 Doll's paper, "The Microlog." 



Acknowledgment is also given William F. Dukes, student at the Colorado 

 School of Mines, for the excellent and accurate drafting of 162 illustrations in 

 both the first and second editions. 



To former President Ben H. Parker of the Colorado School of Mines sin- 

 cere appreciation is extended for his wholehearted support of this symposium. 



I am greatly indebted to the contributors of this volume whose cooperation 

 has made Subsurface Geologic Methods possible. 



The demand for Subsurface Geologic Methods has exhausted the present 

 supply and it has become necessary to issue a second printing. 

 June 1, 1951 L. W. LeRoy 



