Dec 4, 2018
This picture was taken as Lost Hills Park in Springfield, MO. There is another fallen tree here and other vegetation that has gotten between the rocky areas. It is non-moving water, which doesn’t make the rocks in it weathered. The rocks in non-moving water tend to get covered in pond-scum, which tends to get mistaken for algae. There is also moss growing on these rocks. They are both near water and in a shady place. References: https://sciencing.com/river-rocks-formed-5471789.html; https://www.nytimes.com/2016/08/30/science/why-do-algae-grow-in-ponds-in-warm-weather.html