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Volcanic Units SW of the Active Crater
View looking west toward the dead zone, SW of the Active Crater. Group 3 tephras and lava flows are pervasively altered and appear tan to yellow-brown. The Rio Blanco tephra (Group 1) unconformably overlies Group 3 deposits, capping most of the ridge tops in the dead zone.
A) Group 4 lava flow exposed in the Hornillas Hills area. Many of the distal flow lobes (aa lava) of Group 4 lavas exhibit altered rinds around unaltered cores. Although the flows vary in thickness from 4 to 30 meters, they are commonly 10 to15 meters thick and exhibit brecciated basal and surficial horizons.
B) View of volcanic stratigraphy in the dead zone - south of the Von Seebach cone. Group 2 deposits are significantly less altered than Group 3 deposits and thicken rapidly toward Von Seebach (presumably their source). Group 1 (Rio Blanco tephra) blankets the ridge in the foreground.
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