from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of a process acting from below, or describing the result of such a process.
from The Century Dictionary and Cyclopedia
- Originating in the depths of the earth: applied to volcanoes, earthquakes, and kindred phenomena.
Volcanism increased the acidity of water deep underground which then gradually ate away at the surrounding limestone in a process known as "hypogenic karstification".