Pacific Northwest Landforms
The Pacific Northwest is home to many different types of evidence of Earth change over both very long and relatively short time scales. Over the next few pages, let's look at some of the distinct landforms in the Pacific Northwest (many of them National Monuments or Parks) that are associated with plate tectonics and geologic forces.
The Northwest has been shaped by almost every geologic force associated with plate tectonics. Before we begin looking at individual features, let's first identify the plates that are at work, what their direction is, and some of these forces. The map below depicts several notable features and landforms of the Pacific Northwest. How many of these places have you been to?
The Northwest has been shaped by almost every geologic force associated with plate tectonics. Before we begin looking at individual features, let's first identify the plates that are at work, what their direction is, and some of these forces. The map below depicts several notable features and landforms of the Pacific Northwest. How many of these places have you been to?
The Northwest has been shaped by two dominant geologic forces over the last 20 million years:
1) Mantle plumes, including the Yellowstone Hot Spot
2) The subducting Juan de Fuca plate
1) Mantle plumes, including the Yellowstone Hot Spot
2) The subducting Juan de Fuca plate
The image above shows the locations of both flood basalts and volcanoes in the Pacific Northwest, which is one of the most volcanically unique and active places on the planet. The numbers that are increasing from 0.6 at Yellowstone to 16 in northern Nevada (the pink "blobs" across southern Idaho) show the age in millions of years of volcanic basalts as the North American Plate moved west. The "Trench" just off the coastline is the subduction zone where the Juan de Fuca plate is being subducted underneath the North American plate. The image below shows this across a larger area.
The next several pages will introduce you to how these forces have created the landscapes you see as you travel across the Northwest. Ultimately, these landscapes very much determine our weather, climate, economy, culture, and settlement patterns, which is what makes the Northwest such a unique place!