XIV 



PREFACE TO THE FIRST EDITION 



laterally. I think, however, that principles will suffer this way. I have 

 the book in mind for an advanced course in regional or structural geology. 



I hope also that the book will prove attractive to professional geologists, 

 because some of the maps and ideas about the many fascinating problems 

 of continental growth may be new to them. I also trust that they will not 

 hesitate to set me right about any errors I have made. 



Parts of the North American continent are so well known that it did 

 not seem worth-while to do more than describe them briefly and sum- 

 marize the conclusions that have been so well presented by others. In 

 certain areas, however, I had to marshal the evidence and present it in 

 some detail in order to sustain an original interpretation. For this reason, 

 all parts of the continent may not seem equally treated. I had to bear in 

 mind the professional geologist as a reader when drawing original con- 

 clusions. 



A series of paleogeologic maps and paleotectonic maps is included in the 

 book. These, I hope, will be referred to repeatedly. They differ decidedly 

 from the familiar paleogeographic map, and for structural studies are 

 much more illuminating. As geologic studies progress, the maps will un- 

 doubtedly bear correction, but I have been impressed repeatedly with the 

 adequacy of our knowledge to date in establishing many important rela- 

 tionships. 



left 



Where possible I have referred to late summary reports, and have left 

 the reader to go to these, if he wishes all the original references. Where 

 good summary reports are lacking, I have referred to the basic investi- 

 gations. Our literature bearing on die structural development of the con- 

 tinent is so extensive that I have been continuously beset by the fear that 

 I have missed an important reference, especially for those regions with 

 which I am least familiar. 



The research and writing of this book was done at the University of 

 Michigan, where the geologic library is extensive, the departmental facil- 

 ities are all that were needed, the time to do research work was abundant, 

 and my former associates on the staff were most helpful and congenial. I 

 remain very appreciative of these facilities and opportunities at the Uni- 

 versity of Michigan. 



Miss Dolores Marsik has helped over several years as typist, and Dr. 

 Ruth Bastanchury Boeckerman has assisted in editorial work and has 

 done the final typing. Mr. Derwin Bell assisted in the drafting of many 

 of the figures and plates. 



A. J. Eardley 



January, 1951 



