INTRODUCTION

Cascadia encompasses the volcanoes of the Cascade Range and the subduction zone that feeds them. The region is home to nearly 10 million people. Where and how these people live, work, and play are influenced by the shape, or physiography, of Cascadia. This physiography represents millions of years of volcanism, erosion, deposition, and deformation -- a history that also determines the distribution of groundwater, gold mines, gas wells, and gravel pits, as well as hazards from earthquakes, volcanoes, landslides, and floods. This map is a tool for visualizing and interpreting the physiography of Cascadia. It was prepared, using computer techniques, from numerical representations of topography and bathymetry obtained from traditional surveying methods. It is not derived from satellite data, nor is any of it a direct composite of aerial photographs.