Many of you here, I am sure, were at the annual meeting of the Geological Society of America which met in St. Louis in the fall of 1958. Thinking of this, I imagine that you may judge me to be a pretty poor choice for the present assignment, because at that meeting I gave an address, nearly an hour long, on the theme, “Stability of the Earth's Crust.” I had barely finished before an earthquake shook up a four-state area around St. Louis, as newspapers reported the next morning. Such are my credentials. Now I am asked to deal with instability of the crust in a belt that extends along the entire Americas, but I point out that I did not deny then, and do not now, the actuality of crustal deformation. I thought then and I still judge that in the perspective of all geologic time—at least since the end of the Precambrian, and taking account of our entire globe—stability is an outstanding attribute of the crust.
Now it is my task to try to summarize this enormously profitable trip on which we have been led, and I would be remiss, I think, if I did not express thanks on behalf of all of us to the committee that has arranged this series of papers. Anything that I can say, I suspect, will neither add to nor subtract from the benefits you have derived from the extremely fine papers to which we have listened.
Figures 1 and 2 show some of the features that call for review, but not exactly the backbone of the Americas, as topography of the land masses is not represented.
Figures & Tables
Backbone of the Americas: Tectonic History from Pole to Pole
The first article in this book is the address that introduced the technical program of the 46th Annual Meeting of the AAPG. The organization and presentation of this symposium volume was developed in an orderly geographic continuity. Modern concepts of structural form and the sequence of tectonic events are carefully reported all along the mountainous western margins of the American continents. The relationship of this structural knowledge to the accumulation of oil and gas is constantly emphasized in the 26 papers contained herein.