Brian Head, Utah
Exposure of volcanic tuff below the top of Brian head. View is west, cliffs of Cedar Breaks National Monument in the middle ground (red).
Top three layers represent the Leach Canyon formation, deposits from a supervolcano eruption 24 million years ago, originating from a caldera at the Nevada/Utah border approximately 60 miles to the west at the horizon. This eruption ejected approximately 3,600 cubic kilometers of ash deposits .From top thees deposits are:
- moderately welded ash (pyroclastic)flow
-a thick glassy vitrophyre (looks like weathered basalt, but is not)
-a non welded air fall ash deposit (reddish)
The talus slope (ash flow breccia) below and the black outcroppings represent the Isom formation, a pyroclastic ash flow from a 26 million year eruption. This ash flow was by about 200 degree C hotter than usual ash flows, and is typically vitrified it the bottom layers (black outcroppings). The ash deposit volume of this eruption was about 4,200 cubic kilometers.
Brian Head, Utah
Exposure of volcanic tuff below the top of Brian head. View is west, cliffs of Cedar Breaks National Monument in the middle ground (red).
Top three layers represent the Leach Canyon formation, deposits from a supervolcano eruption 24 million years ago, originating from a caldera at the Nevada/Utah border approximately 60 miles to the west at the horizon. This eruption ejected approximately 3,600 cubic kilometers of ash deposits .From top thees deposits are:
- moderately welded ash (pyroclastic)flow
-a thick glassy vitrophyre (looks like weathered basalt, but is not)
-a non welded air fall ash deposit (reddish)
The talus slope (ash flow breccia) below and the black outcroppings represent the Isom formation, a pyroclastic ash flow from a 26 million year eruption. This ash flow was by about 200 degree C hotter than usual ash flows, and is typically vitrified it the bottom layers (black outcroppings). The ash deposit volume of this eruption was about 4,200 cubic kilometers.