sapropel
/ˈsæprəpɛl/
noun
- A dark, muddy sediment rich in organic matter that forms at the bottom of lakes or seas in low-oxygen conditions.
- The lake's bottom is covered with a thick layer of sapropel that smells like rotten eggs.
- Farmers sometimes use dried sapropel as a natural fertilizer for their fields.
- Geologists study sapropel layers to learn about ancient climates and environments.