Science Olympiad Dynamic Planet Practice Test

What process describes the formation of a volcanic cone from eruptions of scoria surrounding a vent?

1. Gradual erosion

2. Centrifugation

3. Pyroclastic accumulation

4. Lava cooling on the vent

The correct answer is: Pyroclastic accumulation

The formation of a volcanic cone primarily through the accumulation of scoria around a vent is best described by pyroclastic accumulation. Scoria is a type of volcanic rock that forms from gas-rich lava that is ejected from a volcano, resulting in a vesicular texture. When scoria is explosively ejected during an eruption, it falls back to the ground and accumulates around the volcanic vent. Over time, repeated eruptions lead to the build-up of these materials, creating a cone-shaped structure known as a scoria cone. This process is characterized by the layering of volcanic debris, which is a hallmark of pyroclastic materials. The explosive nature of these eruptions contributes to the fragmentation of the lava, resulting in the distinctive features of scoria, including its lightweight and porous characteristics. The arrangement of these layers and their gradual piling around the vent forms the structure of the cone, distinguishing it as a unique volcanic landform. Therefore, pyroclastic accumulation effectively captures the essential process leading to the creation of volcanic cones from the eruptions of scoria.