Woods Hole Oceanographic Institution

Author Archive for Chris Conway

A Crystal’s Journey Through Middle Earth

Pumice and lava are the cooled, hardened versions of bodies of molten rock and crystals stored beneath the seafloor that geologists call magma. Prior to being sampled by Jason, volcanic rocks on the seafloor north of New Zealand have experienced long and arduous journeys as magmas, venturing through Middle Earth (much like Frodo Baggins). The ‘Middle Earth’ in our story is the upper portion of Earth’s mantle and oceanic crust where these magmas accumulate, form crystals, and rise to the seafloor, where they erupt.

Between its initial formation and its final stages, a body of magma undergoes a series of changes caused by the formation of crystals, as well as interactions with other magmas and with oceanic crust. In order to understand this epic tale better, and to provide the prologue for why and how pumice and lava was erupted from Havre volcano in 2012, we must look for clues held in crystals found in the samples we are collecting during the MESH expedition. Unlike The Lord of the Rings, this story does not contain wizards or orcs but it does contain some tricky words, which are defined in a glossary at the bottom of this post. There is also a recipe for creating magma (do not try at home) that summarizes the different stages. Read More →