Certain rivers in the Jura are very loaded with bicarbonate (HCO3-) and calcium (Ca2+). They generate different types of carbonate concretions depending on the inclination of their slope. These concretions range from simple stromatolithic balls, in relatively calm water, to suites of travertine gours and dams, in the case of steeper slopes, to real waterfalls - such as here the Tufs waterfall in Planches-près-Arbois - when the break in the slope is very important.