There’s both a Western Wall and an Eastern Wall marking Cascadia’s boundaries….
The Western Wall.
Cascadia rises as a great flying arc of landscapes perched on the verge of Mountains and the Sea, curving around the northeast section of the Pacific Rim. On the western margin of Cascadia, stand the high steep ramparts of the Cascade Range, the B.C. Coast Mountains, and the Icefield Ranges of SE Alaska, a thousand mile long wall. This high steep barrier blocks the full blast of the North Pacific Wave, which is forced to climb up-and-over the wall of mountains, squeezing out moisture, before it descends, drying out the Eastslope and Interior Plateaus. This “orographic precipitation” playing across the north/south running mountain ranges generates an alternating rhythm of west/east facing Windward/Leeward sides, the ubiquitous Rainsheds and Rainshadows. This creates the basic land & climate matrix of Cascadia’s many topoclimates.
“These mountains wall well,” as Annie Dillard observed. And they protect us from raw exposure to the rough winds and waters of the outer rocky coast of the stormy North Pacific Ocean. (“The Inside Passage” to Alaska is preferred, of course, because its sheltered….) Hence, the Westslope naturally falls into exposed and sheltered sides, depending on the way you face….
The Eastern Wall.
Winter Cold the Eastern Wall of Cascadia January 18 – 19, 2024
But when we move all the way across to the Eastern Wall, everything reverses. As this picture shows, the Eastern Wall of the Northern Rocky Mountains protects us from prolonged exposure to the bitter cold sub-arctic easterlies blowing down off the High Plains. (In many ways, the High Plains are the opposite or “other side” of Cascadia. The High Plains stand in the lengthened rainshadow of the Rockies–they’re the old interior seaway now expressed as a great prairie, an ocean of grass, as well as an open highway stretching both north and south). The Eastern Wall protecting us against extreme cold is the Continental Divide!
Hence, Cascadia is a two-sided place, enjoying protection from harsh weather extremes of both open Ocean, on one side, and the High Plains, on the other. Both walls are mountain ranges–the Western Wall is the near-coastal mountains, while the Eastern Wall is the Continental Divide. They stand forth as mirror or reversed images of one another. Thus, Cascadia is the sheltered liminal land in-between the extremes, joining the two halves of the West together….
Cascadia dwells within….
David McCloskey
© 1/2024 Cascadia Institute
McCloskey’s description of the Western and Eastern Walls is subtle and fascinating. I don’t have the geographical and geological knowledge to assess the Gulf Coast the same way, but I have experienced the trip from the latitude of Memphis to that of New Orleans a few times, and the change in elevation is clear if you pay attention. Also the increase in humidity, which grows to unbearable proportions in summer in the Louisiana delta. What occurs to me as far as the landform is concerned– is the image of a doorstep, the doorstep to the North American continent, that this shelf of land creates (please pardon the mixed metaphors) a step up to the landmass.