Here's a breakdown:
* Biogenic: Meaning "originating from life"
* Sedimentary: Formed from the accumulation and cementation of sediments.
There are two main types of biogenic sedimentary rocks:
1. Organic: Composed primarily of carbon-rich organic matter, like coal, oil shale, and some limestones. These rocks formed from the accumulation of plant or animal debris.
2. Bioclastic: Made up of fragments of skeletons, shells, or other hard parts of organisms. Examples include:
* Limestone: Often formed from the accumulation of marine organisms like corals, mollusks, and foraminifera.
* Coquina: A coarse-grained limestone made up of shell fragments.
* Chalk: A fine-grained limestone made up of microscopic plankton shells.
So, whenever you see a rock with visible fossils or hints of organic matter, you're looking at a biogenic sedimentary rock!