Waimea Canyon from the lower lookout, Kauai, Hawai'i

Erosion Always Wins: Kauai


In WC’s Geomorphology class, on the first day, the professor (whose name WC has forgotten) told us, “If you only take one thing away for this course, it should be this: Erosion always wins.” If you need proof of that claim, you should visit Kauai, the oldest of the principle islands of the Hawai’ian Islands.…

Upper Hulls Gulch Trail, looking east, Autumn 2019

Boise Front Notebook: Geology is Messy


The Boise Front is the local name for the foothills that rise steeply up behind Boise to the southwest side of the Idaho Batholith. It’s a dramatic setting; a wall of steep mountains that appear to go straight up, immediately behind the city. The reality is much more complex.  Boise lies on the northern edge…

A slice through Earth’s mantle under the Andes. © Jonny Wu, University of Houston

The Answer Is Blowing in the (Mantle) Wind


Geology went through a Kuhnian revolution in the 1960s and 1970s, with the emergence of plate tectonics as an explanation, as a mechanism, driving what geologists were observing in the field. Plate tectonics has settled in as a credible, definitive and confirmable explanation of everything from vulcanism to oceanic trenches. But it’s also an incomplete…

Granodiorite, with an intrusive vein of quartzolite, Payette River canyon, Idaho

Geology 101: Granite Is Hard!


Non-geologists think of granite as – sorry – monolithic. Igenous rock that cools underground, right? You know, as opposed to lava, which cools on the surface. Well, geology is messy. And granite is messy, even for geology. Yet the kind of “granite” matters, because the chemical composition of rock determines how it weathers, how quickly…

Idaho Batholith at Lick Creek Summit, northeast of McCall, Idaho

Geology Is Messy: The Idaho Batholith


The Idaho Batholith is a vast chunk of granite that dominates central Idaho. It’s some 15,400 square miles of rock. People talk about it as if it’s a gigantic, homogenous lump of stone. It’s not. Geology is complicated. Most, but not all, geologists agree the Batholith was formed when the Pacific Plate subsumed under the…

A schematic model that links the slab hole with other physiographic features. The view is from the east, and theJuan de Fuca slab is shown in blue. The propagator wake (bold gray line underneath Oregon) causes a weakness in the slabalong which a tear is propagating. The High Lava Plains (contours in Oregon) lie above the southern edge of theslab hole. The Gorda slab rotates clockwise, causing intraplate seismicity in the Gorda region.

Untangling Oregon Volcanism


Most of Oregon is igneous rock. Pretty recent igneous rock, as geologists measure time. It’s almost embarrassing. While some of it is pretty well understood, parts of all that volcanism are unexplained. The stratovolcanoes of the High Cascades? Subduction of the Juan de Fuca Plate and Pacific Plate. The lava that flowed into the Pacific…

Acipenseriform fish with ejecta clustered in the gill region. (A) X-ray of a fossil sturgeon head (outlined, pointing left; FAU.DGS.ND.161.115.T). (B) Magnified image of the X-ray in A showing numerous ejecta spherules clustered within the gill region (arrows). (C and D) Micro-CT images of another fish specimen (paddlefish; FAU.DGS.ND.161.29.T), with microtektites embedded between the gill rakers in the same fashion.

The Best Evidence Yet for the Dinosaur Killer


Archaeologist Robert A. DePalma, working in Southcentral North Dakota, has found the best evidence yet that the dinosaur killer, the huge meteor that struck the Yucatan Peninsula, leaving the Chicxulub crater, did indeed kill the dinosaurs. He has found, entombed in the rocks of the Hell Creek Formation, the archaeological equivalent of a smoking gun.…