Ohio Assessment for Educators (OAE) Integrated Science (024) Practice Exam

What type of lava flow is typically produced by shield volcanoes?

1. Pumice

2. Basaltic

3. Volcanic ash

4. Obsidian

The correct answer is: Basaltic

Shield volcanoes are primarily characterized by their broad, gently sloping profiles and are predominantly built up by the eruption of low-viscosity lava that can flow over long distances. The type of lava that is typically produced by shield volcanoes is basaltic. Basaltic lava is high in iron and magnesium but low in silica, resulting in its low viscosity. This allows it to travel far from the eruption site, contributing to the formation of the wide, shield-like shape of these volcanoes. The fluidity of basaltic lava leads to relatively non-explosive eruptions, which is a key feature of shield volcanoes. Other types of lava, such as pumice, volcanic ash, and obsidian, are associated with different volcanic activities or types of volcanoes. Pumice forms from explosive eruptions that create gas-rich lava, while volcanic ash results from the fragmentation of volcanic material during eruptions. Obsidian is a volcanic glass that forms when lava cools very quickly, typically during explosive volcanic eruptions where the magma has a high silica content.