Tephra is a general term for all fragmented material produced and ejected into the air during a volcanic eruption. This includes everything from fine volcanic ash and dust to medium-sized lapilli and large volcanic bombs. Once tephra falls to the ground, it often consolidates to form a rock known as “tuff.” ANSWER: (B) All types of airborne volcanic ejecta.
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In the study of volcanic mountains, Tephra represents the “pyroclastic” (fire-broken) material thrown into the atmosphere. Unlike lava, which flows along the ground, tephra is carried by eruption columns and wind. The size of tephra particles determines how far they travel; fine ash can encircle the globe and affect climates, while larger bombs fall near the vent, building the steep slopes of cinder cones. Geographically, tephra deposits are crucial for “tephrochronology,” a method where layers of ash in the soil or ice cores are used to date geological and archaeological events with high precision.