Sand Dunes? Really?


You probably think of sand dunes as a desert phenomenon. But you can get sand dunes wherever you have (1) a decent supply of coarse-grained sand, (2) an area where there is enough topography to create a trap for the sand, and (3) relatively equal distribution of the winds, or at least no prevailing single…

Two Approaches to Teaching Geology


WC has read two lay geology books recently, and the contrast in their approaches to the rocky science is itself instructive. Both are fine examples of cogent, readable explanation of geology, in this case the geology of the Great Basin. The first is Frank DeCourten’s The Great Basin Seafloor, which is a geologic history of…

Geology, Catastrophism and Lake Missoula


In the late 18th and early 19th Centuries, there was a mighty struggle in the nascent science of geology. Biblical literalism had insisted on a young earth, created less than 10,000 year earlier, and a literal, world-spanning Noachian flood. As the evidence for a much older earth accumulated, and the evidence against a global flood…

A [Belated] 20th Anniversary


It was the second strongest earthquake WC has experienced. Only the Good Friday Earthquake in 1964 was stronger. But the November 3, 2002 Denali Fault Quake was M 7.9, and the epicenter, under Susitna Glacier, was only 82 miles from Fairbanks. It’s worth marking the anniversary, and noting what geologists have puzzled out about the…

Geology: The Galapagos Triple Junction


In plate tectonics, a Triple Junction occurs where three tectonic plates, all moving in different directions, touch. For example, off the west coast of the United States is the Mendicino Triple Junction, where the San Andreas Fault, a strike-slip fault and transform plate boundary, separates the Pacific Plate and the North American Plate. To the north lies the Cascadia…

Seismic Tomography and Yellowstone: An Update


WARNING: Still more geeky geology ahead. And, WC acknowledges, some pretty serious oversimplifications of complex stuff. WC has written about seismic topography before, the evolving technology that uses the seismic waves from earthquakes to analyze subsurface geologic features. The technology has even been used on Mars to study xenogeology, albeit in a more simplified form.…

Notes on Plate Tectonics


WARNING! Seriously geeky geology ahead. Most folks who were exposed to even a little bit of geology in school understand vaguely the idea of plate tectonics. They get the basic idea that big chunks of the surface of the earth are somehow moving around. But there are lots of non-obvious parts of the science of…

Geology Is Messy: Lime, Oregon


You won’t find Lime, Oregon on a map; at least not one published in the last forty years. Lime isn’t even a ghost town; it’s obliterated, along with the cement plant that was Lime’s reason for existence. Today, Lime is a wide spot in a side road off Interstate 84, not too far from Baker…

Field Notes: Glacial Moraines


While the State of Idaho has many fine points, it does not have glaciers worthy of the name. It has had them in the past, and they did some dramatic alteration of the terrain, but those glaciers are long gone. While the ice may have all melted, the geologic signatures of glaciers are everywhere. Among…

Field Notes: Burgdorf Hot Springs


The place name “Secesh,” including the lovely Secesh River in central Idaho, has a romantic, American Indian sound to it. Unfortunately, it’s short for “secessionist,” and a name given by refugees from the South in the American Civil War. The territorial history of Idaho reads as a struggle between Federal, pro-Union appointed officials and popularly…

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…