The United Plates of America


Most of Alaska, like most Alaskans, originally came from somewhere else. John McPhee, Assembling California WC’s second year geology classes at the University of Oregon – prosaically enough, Geology 201, 202 and 203 – were taught mostly by visiting professors. The second quarter class focused on structural geology, a refreshing change after the tedious and…

Thwaites Gets Ribbed


“Thwaites,” in this instance, is Thwaites Glacier and Ice Shelf, located in Antarctica, west and a little south of the Antarctic Peninsula and Ellsworth Land, it dumps into the Amundsen Sea. “Ribbed” is, well we will get to that in a minute. Thwaites has gotten a lot of press. Rolling Stone, back in 2017, called…

Geology in Real Time: A Barry Arm Update


The thing about landslides is that they move in slow motion until they don’t. WC has written earlier about the potential landslide-generated tsunami in Barry Arm. This is an update. Barry Arm is a glacial fjord in northwestern Prince William Sound, Alaska. The westerly wall of Barry Arm is badly fractured rock, hanging hundreds of…

Fossil Lakes and Tuff Rings


During the Pleistocene, as recently as 12,000 years ago, central Oregon had a number of large lakes. One of them, Fossil Lake, located in south-central Oregon, in northern Lek County, was, at peak, about 30 miles wide and perhaps 250 feet deep. It’s vanished now. The last two ponds evaporated about 1877. But during the…

A Visit to Mt. Mazama


7,700 years go, give or take 1.5%, the 12,000 foot high stratovolcano Mt. Mazama catastrophically erupted, blasting so much ash and molten rock from its magma chamber that the whole edifice collapsed, creating an oblong caldera six miles long on the longer axis, four and a half on the shorter one, and nearly a mile…

Geomorphology and the Idaho Batholith


WC cautions readers that this post is mostly WC’s speculation, geology ex cathedra WC’s bellybutton, as it were. But it is at least slightly informed speculation. Let’s talk about stream courses in the Idaho Batholith. Anyone unfamiliar with Idaho who tries to trace the course of the Salmon River on a map will find the task immensely…

Marsquakes! For Science!


In principle, at least, the use of seismic – earthquake – waves to understand the interior of a planet is less complicated than it first seems. You’re probably familiar with bats’ use of echolocation to navigate the night skies: they emit high-pitched squeaks, and then use the reflections, the echoes, to navigate and find prey.…

The Alvord “Desert”


It’s not a desert, although the area only gets about seven inches of precipitation a year, on average. It’s a playa, the dry bed of a former lake, and it’s about 8 miles wide and 70 miles long. The surface of the dry lake bottom is absolutely, unnervingly flat, and bare of any visible trace…

Salt Domes and High Island


A reader, in response to WC’s point that High Island is the result of a subterranean salt dome, asked what a “salt dome” was. It proved to be an irresistible opportunity for WC to geek out on geology. Imagine a salt pan, an area where salt is a major constituent of surface deposits. The Great…

Notes from 37,000 Feet


It’s an 11.5 hour flight from San Francisco, California to Tokyo, Japan. Technically, it’s a day long flight, since you cross the International Date Line and arrive a full day later than you started. Here are some notes from WC’s flight. WC left Boise, Idaho. That town is located on the Boise River, which flows…

Thailand: It Starts with the Rocks


The geology of Thailand and the whole Indochinese Peninsula was already complex before the Indian subcontinent careened north-northeast across the Indian Ocean and collided with the underbelly of southern Asia. The Indochinese Peninsula is assembled from a number of terranes that accreted to southeast Asia, much as was the case with western North America. By…

Geology in Real Time: the M8.9 Honshu Earthquake


The IRIS Education and Public Outreach (EPO) program has some very spiffy visualization of earthquake activity that captures the movement of the surface of the earth in the course of an earthquake. Check out this display of ground movement from the Honshu earthquake: Here’s the more recent deep earthquake in Peru: WC understands many readers…

Isostatic Rebound: It’s Complicated


Back when WC was a sullen teenager, he worked one summer on the University of Alaska Institute of Marine Science’s R/V Acona, a research ship. In the Acona’s skiff, we made a practice run northwards up Gastineau Channel to Auke Bay, measuring water depth and sampling bottom sediments. Today, some 54 years later, much of…

Field Notes: Bruneau Sand Dunes


The Bruneau Dunes – more properly, the Bruneau Dune – are an accident of geomorphology. The Bruneau Dunes are in the Snake River Canyon in south-central Idaho. It’s a stretch of the Snake River that cuts through the lake bottom sediments from the long-vanished Lake Idaho instead of the ubiquitous basalt that’s more common along…

Experiencing the Blues


Geology posts two days in a row? Is WC turning into some kind of sadist? Nope. At least no more than usual. Just the Magpie Principle in action. If you had stood on the Pacific shore about 190 million years ago – a seacoast then located near today’s Oregon-Idaho border – you might have seen…

Geology in Real Time: Even Newer Islands


Back in June 2015, WC wrote: Most geological processes happen too slowly for brief human life spans. The Rocky Mountains will erode down to a plain eventually, but not while we are watching. As a result, geology is largely a matter of inference. There are exceptions. There are geological processes that happen at speeds humans…

You Want Complex Geology?


WC has gotten complaints that geology is too complex. Piffle. Until now, WC hasn’t tackled complex geology. Nevada’s geology is notoriously, infamously complex. WC had a glimpse of that complexity in his recent hike in the Ruby Mountains in northeastern Nevada. While Idaho has some interesting geology, for the most part everything but the volcanism…

Geology Matters: Haiti and the Enriquillo Fault


WC gets a lot of blowback from readers on his geology posts. “Who care about rocks?” one reader wrote. Yet geology really, really matters, and WC will offer one case in point, from the island of Hispaniola,1 to illustrate his claim. Hispaniola, the island divided between the Dominican Republic on the east and Haiti on…

The Batholith Meets the Overthrust


WC and Mrs. WC recently concluded a trip into North Idaho, up the Lochsa River over Lolo Pass, then south down the Bitterroot River Valley and up over Lost Trail Pass. We explored part of East Idaho for a bit, and then headed west across southern Idaho with a delightful stop on the Little Wood…