Rocks

As dissolved gases are released from magma, bubbles will begin to form. The dissolved gases can escape only when the vapor pressure of the magma is greater than the confining pressure of the surrounding rocks. The vapor pressure is largely dependent on the amount of dissolved gases and the temperature of the magma. Viscous lava flows often contain vesicles (gas cavities) which form when gases escape and form a bubble hole.

Author’s collection – vesicular basalt (sample on Mt. Etna, Sicily, Italy)

With support from the Center for Applied Technologies in Education, The Earth Science Digital Library is an initiative authored by Russell Agostaro, Newburgh Enlarged City School District, Newburgh, New York.

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