Phillip S. Kane

A nice little book about the geology of Lassen Volcanic National Park in California. The original dates from 1979 (although it’s been reprinted several times but not changed); however the only out-of-date reference I could find is that the almost completely eroded volcano referred to in this book as “Brokeoff Volcano” is now usually called Mt. Tehama

Lassen Peak has a number of interesting features. It’s the southernmost volcano in the Cascades, it’s the only Cascade Volcano that’s an extruded dome instead of a composite volcano, it’s the world’s largest dacite dome, and, until Mt. St. Helens, it was the last volcano to erupt in the conterminous United States (1914-1921). I was rather surprised to find that it’s relatively recent as volcanoes go; although there was volcanic activity in the general area all the way back to the Pliocene, everything in the area was quiescent from 27 kya to 1200 ya. Then things started up again. Lassen Peak itself extruded in a few years, and the park and surrounding has lots of other relatively recent extruded domes, tephra cones, and basalt flows. The 1914 eruption was interesting, because extruded dome volcanoes like Lassen are generally “self sealing” and subsequent eruptions occur on the flanks or further away; however, the 1914 eruption was definitely from the summit so the magma must have tunneled vertically through the dacite plug to break out. The eruption included a pyroclastic flow and a lahar; nobody actually witnessed these (which is probably quite fortunate for them) but the aftermath was pretty clear (and still is).

The only flaw is that there’s no road or trail guide; not a book to read while driving or hiking but one to read before of after, to learn what you are going to see or what you just saw.… (mehr)