What are the deep vertical formations through which diamonds traveled to the surface called?

The correct answer, "pipes," refers to the geological structures known as kimberlite pipes, through which diamonds are brought from the Earth’s mantle to the surface. These pipes are formed from deep volcanic eruptions that create vertical shafts filled with kimberlite rock, which can include diamonds among other minerals.

Kimberlite pipes are significant because they provide insight into the conditions under which diamonds form and are transported. Once a kimberlite pipe erupts, it leaves behind a cylindrical, vertical, and usually hardened column of rock, which is mined for its valuable gem content. Understanding this process is critical in the diamond industry, as it informs gemological origins and geologic exploration.

The other terms listed, while they might describe geological features, do not accurately represent the specific formations that are crucial for diamond transport to the surface.