Science Olympiad Dynamic Planet Practice Test

What is created when viscous lava forces upward causing the surface of a mountain to bulge?

1. Lava domes

2. Cinder cones

3. Volcanic cones

4. Stratovolcanoes

The correct answer is: Lava domes

When viscous lava forces its way upward and causes the surface of a mountain to bulge, this phenomenon typically results in the formation of lava domes. Lava domes are characterized by their steep, dome-shaped structures which form from the slow accumulation of viscous lava that piles up near the vent. Unlike other volcanic formations, lava domes are built primarily from the flow of thick, highly viscous lava that doesn't travel far from the source, leading to the gradual buildup of material. This process can lead to impressive and distinct landforms that can sometimes collapse or produce explosive eruptions as pressure builds beneath the dome. Their formation contrasts starkly with features formed by more fluid lavas, such as cinder cones or stratovolcanoes, where lava flows spread over wider areas. Understanding this mechanism gives insight into the different types of volcanic activity and the shapes they create on the Earth's surface.