The Oregon Cascade Range is ... complicated. From the surface it looks like the chain of volcanoes that we started exploring back in British Columbia remains the same. However, once you start looking at the deep geologic processes that are causing volcanoes in Oregon, you quickly realize there is a lot going on.
"How much?" you say? Here's a short list:
The Juan de Fuca plate is still subducting (sliding underneath) North America just off the Pacific Coast.
Much of the basin that follows the Columbia River is filled with basalt lava from the largest flood basalt period in the last 50 million years.
The high Cascades from Hood to Three Sisters sit in a graben (valley) with faults bounding both sides of the range.
Multiple major fault zones intersect the Cascade Range.
The High Lava Plains - a ~10 million year old chain of rhyolite and basalt volcanism that gets younger to the west -- intersect the Cascade Range near Bend, Oregon
The Basin & Range -- the province that creates the mountain belts and valleys in western North American -- starts in the southern part of Oregon just to the east of the Cascade Range.
We're not going to get into the "why" of all this, but the volcanism along the Oregon Cascade Range is definitely influenced by a bevy of these tectonic factors. The other fun thing about the Oregon Cascade Range is that I do a lot of my research there, so I think a lot about them.
As usual, you can find the high resolution version of these Sentinel-2 images here.
