July 29, 2014 | 1
Outside of Glacier Peak, Mount Baker seems to be the least-regarded of the I-5 corridor volcanoes. Mounts Hood, Helens, and Rainier seem to suck up all the ooing-and-awing oxygen. Baker, not as much.
But it repays attention. For one, it’s active. For two, it’s not monitored closely enough. For three, it’s got a surprising amount of various volcanic deposits all visible during a leisurely trip up Mount Baker Highway. You don’t even have to get an early start.
B and I took our first trip up there on Monday. We’ll certainly be back for more in-depth investigation. For now, I shall give you a preliminary report with lovely photos, and you can look forward to more in the hopefully not-distant future.
Here are 5 reasons that if you’re a fan of awesome volcanic deposits plus scenery, you should put Mount Baker on your bucket list:
You like columns, right? We all love columns. They’re columnar! And Mount Baker has columns everywhere. Here’s a small sampling for ye:
At the Heather Meadows Visitors Center, you can see lots of lovely columns, some exposed, some polished off by glaciers, and some made in to walls and steps and all sorts of useful-to-humans things. These flows are much older than the Mount Baker cone: the Table Mountain andesite erupted about 300,000 years ago.
2. An ancient caldera and a young whippersnapper
You all know what a caldera is, right? Well, head a bit up the road to Artist Point, and you’re standing on one. You can look down into the Swift Creek drainage, and see the old caldera walls, with much younger volcanics atop it – including lovely Mount Baker.
See that pale, crumbly stuff near the bottom of the photo, creating cliffs even our intrepid Pacific Northwest plants can’t conquer? That’s the intracaldera ignimbrite of Kulshan Caldera. Basically, Washington’s own Crater Lake, only not quite as catastrophic. This maclargehuge mountain was here about 1.15 million years ago. Operative word, was. It went kablooey in a major way, blowing a 4.5 x 8 km (3 x 5 mile) caldera into the landscape. It filled itself with rhyodacite fragments, basically. We think it must have erupted through glacial ice, because the stuff cooled too quickly to weld together when it landed. Some of it made it at least as far as Tacoma. Wow, amirite?
After the caldera eruption, the volcanic center wasn’t done. You see that kind of knobby thing above the flat bit on the right, right in front of the lovely white snowcone of Mount Baker? That’s Ptarmigan Dome, which is a rhyodacite lava dome. Topping off the scene is Mount Baker its own self, which is a sprightly 40,000 or so years old. The summit you see had its finishing touches put on within the last 20,000 years. It’s just a young kiddo.
3. Platy andesite
There are spectacular exposures of platy andesite along the road to Artist Point.
So, the smaller the column, the quicker the cooling. How about plates? Possibly andesite flowing on or alongside snow or ice.
4. Mount Shuksan
Look, a greenschist mountain! It looks gray, right?
Up close and personal, though, you’d see it’s mostly green, with a bit of blue – metamorphosed basalt from an ancient ocean floor. It’s the Shuksan Greenschist! Getting cooked around 120 million years ago reset all the atomic clocks, so we don’t know how old the parent rock actually is – but at least one source considers it likely the stuff is as old as early Paleozoic, which means we may be looking at rocks that erupted under the seas more than 380 million years ago.
5. Nooksack Falls
It’s the Pacific Northwest – of course there’s gonna be a waterfall! And I have one for ye that’s flowing over lava erupted under a Jurassic ocean.
This lovely, blocky brown stuff is 180 million years old, and forms a bonza resistant platform over which the Nooksack River flows. What’s really wild is seeing a wee creek next to it eroding deeper than the actual river – I’ll ‘splain soon, with pictures.
(Now, if you visit this part of the scenery, do stay behind the fence. The rocks along the lip of the falls and the river cliffs are mossy and slippery, and people have died here. Stay behind the fence!)
There ye are, my darlings: a quick guide to just some of the volcanics on offer at Mount Baker. And I haven’t even gotten in to the layers of Mazama ash, or the odd case of the orphan lava that everybody noticed by nobody investigated for a damn long time. We’ll add Mount Baker to our list of Cascades volcanoes to get to know up close and personal, then, shall we?
Babcock, S. and Carson, B. (2000): Hiking Washington’s Geology. Mountaineers Books: Seattle, WA
Tabor, R.W. and Haugerud, R. (1999): Geology of the North Cascades: A Mountain Mosaic. Mountaineers Books: Seattle, WA
Tucker, D., and Scott, K.M. (2010): Volcanic Deposits at Mount Baker, Washington, Tephra, Lava, Lahars, Cinder Cones, and a Caldera. Northwest Geological Society Field Trip Guidebook #25.
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