Lava domes are rounded, steep-sided mounds built by magma that is highly resistant to flow, usually either dacite or rhyolite. Such magmas are typically too viscous to move far from the vent ...

According To Chefs To make your onion volcano, follow the technique used by all the best hibachi restaurants in the U.S. Per chef Steve, start by peeling a dome-shaped onion and cut it in half.