Evolution of river systems
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2014/04/scivis_feat.png?fit=840%2C460&ssl=1)
RUNNING WATERS When a value called χ varies across watershed boundaries, as it does along the crest of the Blue Ridge Mountains (thick white line), the river networks are still evolving and the ridge is shifting, a new study shows.
S.D. Willett et al/Science 2014, Courtesy of Science/AAAS