Products of this rhyolitic eruption are pumice and obsidian, the volcanic glass that Native Americans used to make arrow points and scrapers.

The material that was thrown into the air by the steam, mainly old lake bottom sediments, was deposited around the new vent in little mounds.

[6] Following the violent eruptions of the first two phases, the remainder of the thick magma slowly rose to the surface in a series of domes.

Each dome began with an outpouring of the viscous, rhyolitic lava which hardened and formed a cap over the vent.

The formation of the spires was analogous to toothpaste squeezing through the opening of a tube and forming a small tower before it topples over.

[6] The central lava dome was erupted from degassed material and is made up of pumice and obsidian of the same composition.

As the magma rose towards the surface where there was less pressure on it than at depth, the gas expanded producing the holes or bubbles in the pumice.