Notes from the Authors

Geologists love to debate details but are often loath to summarize in generalities, probably because most of us are trained as specialists rather than generalists. As a result, there are few recent summaries on the geologic evolution of Washington State and the Pacific Northwest. What does exist is an extensive body of professional literature that holds a truly fascinating story yet to be told.

Some of our colleagues have argued that it is premature to piece together such a big story at this time -- a view with which we must respectfully disagree. We believe that the "big picture" principles that have guided regional geologic evolution in the Pacific Northwest have been broadly validated. We also think that our region is such a spectacular showpiece for those principles that it is a story well worth sharing with the public.

We have applied our own interpretations on how the course of geologic evolution in Washington and the Pacific Northwest is fundamentally structured.  We interpret this course as consisting of two regimes, one covering the evolution of the largely passive continental margin over the last supercontinent cycle involving Rodinia, and one covering the evolution of the largely active margin over the current supercontinent cycle of Pangaea. In our interpretation, the latter is divided into four distinct episodes marked by major changes in the relationships between the continental and oceanic plates along the evolving continental margin. We have named these four episodes after the continental arc regimes that have in part characterized the geologic history of each episode.

Within that structure, our role in creating this online exhibit has largely been an editorial one. Relying on our own many years of experience in the Pacific Northwest from Alaska to Washington, we sifted through the volumes of professional literature and selected those interpretations we believe are the most accurate reflection of the actual course of events in the geologic evolution of this region. It is a process that is obviously subject to our professional biases, and one that in the end rejects a variety of alternative interpretations. In a later version of this exhibit, we hope to explore in more detail the interesting controversies that exist in the geologic history of Washington and the Pacific Northwest.

Acknowledgements

Summary works like this are largely to the credit of the hundreds of diligent researchers who have been studying this remarkable region for the last fifty years.  In particular, the works of the late Richard Armstrong (University of British Columbia), Edwin (Ned) Brown (Western Washington University), Jim Monger (University of British Columbia) and Rowland Tabor (USGS) have had a particular influence on this synthesis (although this is not to say that they would necessarily agree with our conclusions).

A special note of appreciation is offered Ralph Haugerud (USGS) and Tracy Furutani (North Seattle Community College) who have always generously indulged John’s interest in this field, and to Eric Cheney (University of Washington) who encouraged our development of this organizational format.  We are also greatly indebted to Liz Nesbitt (University of Washington) for her continuing enthusiasm and support of this project.  John thanks his wife, Julie Bonnington, who lent her support in so many ways.  Cathy thanks her colleagues Neil Carroll, Susan Libonati, Ron Eng and Ruth Pelz for suggestions throughout this project.  Richard L. Johnson first introduced me to the geology of Washington and originally suggested this project.

The publications of Elizabeth L. Orr, William N. Orr,  David Alt and Donald Hyndman have influenced our thoughts on introducing regional geologic history to the public.

This project was funded by the National Science Foundation, the University of Washington, the Burke Museum and the Robert Frost family.

John Figge

Cathy Townsend

Seattle, Washington

October, 2002