Below the waterfall |
scale in cms
The shales and mudstones below the cap of the waterfall contain many different types of fossils. Especially common are clams, snails, trilobites, thin-shelled brachiopods and lacy-looking colonies of bryozoans. Missing from these rocks are thick-shelled fossils and heavy coral colonies, which are common in the limestones. Why?
These shales and mudstones probably represent soft or even soupy sea-floor conditions. Large, heavy coral colonies or thick-shelled brachiopods would probably sink into the mud and die. Most clams today live below the surface of the mud, so similar ancient clams probably also thrived in mud bottoms. Many of the other fossils represent animals that could move around and could escape sinking into the mud.