Obsidian, asphyxiation, and other fun stuff

Obsidian 1.jpg

Obsidian litters the ground of Kilimanjaro. This brittle stone is formed by the rapid cooling of lava and disintegrates to sharp slivers (it makes good blades!). The accumulation of black lava and ash from Kibo’s repeated eruptions covers a footprint of 388,500 hectares (larger than the state of Rhode Island). It offers a striking contrast to the white ice of the summit.

I cannot think about obsidian and stratovolcanoes without thinking about Pliny the Elder. Pliny was a naturalist from the era of the Roman Empire. He wrote many volumes dedicated to geography and the natural world.

In volume 36 of his magisterial Natural History, Pliny gives attention to a volcanic glass called “Obsian.” He gives it this name because one “Obsius (or Obaidius in an older reading) discovered (it) in Æthiopia” (see more here).

Iconically, the man who handed the word “obsidian” to the modern world died in a volcanic eruption of his own. Pliny was asphyxiated when Mt Vesuvius blew its top in AD 79.

Approach to Lava Tower 3.jpg

When approaching the Western Breach of Kilimanjaro’s summit, the hiker is confronted with great flows of volcanic rock. A formation known as Lava Tower appears on the upper right side of this image.

Kilimanjaro was a break for me. My regular summer work focuses on the area of Israel-Palestine. If you are interested in experiencing the geography, history, and culture of the Bible Lands, email me at or check out our list of future trips here.