Continuing the igneous textures theme of the week, today’s deskcrop is a piece of the Bishop Tuff and it displays a very nice pyroclastic texture. This sample is from near the top of the service road that descends to the bottom of Owens Gorge, and as such, is relatively high in the stratigraphic section of the extrusive volcanic products of the eruption that formed Long Valley Caldera 760,000 years ago. You’ll note that pumice fragments are still relatively undeformed at this stratigraphic level, yet the ash is consolidated enough to make this something that I can honestly call a rock. Future deskcrops from this locality will illustrate the increasing deformation of the more welded samples of the Bishop Tuff from lower stratigraphic levels.
Explore this and all of my 2010 Deskcrops and Outcrops in Google Earth!