Published online by Cambridge University Press: 01 May 2009
Analyses of eighteen samples from Jurassic marls and limestones show a large, continuous range in carbonate-clay composition. The significance of the carbonate/clay ratio is discussed, and it is show that rapid lateral and vertical transitions from marl to limestone may either reflect major changes in composition or represent only small shifts (across a critical value: 4) in the carbonate/clay ratio. The term “marl” is defined.