• Specimen Number

  10

• Description

  Cross section of slab of highly vesicular basalt with vesicles aligned horizontally and diagonally to the upper left in this mounted specimen. Flow was possibly from right to left (?) in this orientation, as shown by tabular shape and diagonal of rising vesicles in zone to right.

• Classification

  Igneous. Volcanic. Extrusive. Basalt. Vesicular

• Location & Occurrence

  Likely from the Snake River Plain, which is similar to, but younger than the Columbia River Basalt Group (CRBG).  Its thick layered lava flows are flood basalts. Volcanic activity began 11-12 million years ago from a mantle plume, hotspot, and continues with the volcanic activity of Yellowstone today. The track of the hotspot can be seen in the brown color on the geological map, tracking from west southwest  to east northeast. Everything else is mountainous at this scale.

• Geological Age

  Cenozoic, mainly Miocene postdating 11-12 million years ago (Ma).

• Geoheritage

  Volcanism here is a continuation of the CRBG, the world's largest intact, well-exposed flood basalt province.  The plain is where most of Idaho's cities and its agricultural activity is.  The hazard of a Yellowstone's hot-spot supervolcano is best realized in the stone pavilion by this related specimen.

• Links

  Link to State Geological Map from USGS.  Link to Idaho Geological Survey.  Link to USGS Columbia River Basalt Group.

• Other

Click here for an explanation of categories and illustrations