The recent warm weather in Richmond has tempted many people to come out to the James River in anticipation of spring. Whether you put in for a paddle, went for a walk, went biking or running along Riverside Drive or driving across the Boulevard Bridge, you may have noticed all of the white granite boulders in the river. What caused all of the rocks to turn white? Why do the rocks have rings around them?
Ralph White has been the park manager and naturalist for the James River Park since the early 1980s, and has had this question asked many times. He knows about most things that happen in the James in Richmond, and this one was an easy one for him.
“Calcium deposits. In the summer, when various algae forms grow vigorously in the warm and sunny waters, the calcium is picked up and put into plant tissue. In the winter, it isn’t. When water levels drop (as they have now) there is a deposit on the rocks,” White said.
Essentially, we haven’t had a significant rain in a few weeks and the water levels have slowly dropped, down to about the four-foot mark this weekend. As the water has dropped, more rock surface is exposed, and more calcium deposits are exposed, and they make the rocks appear white. The white rings on some of the rocks I observed were very straight, almost like the white had been painted on.