Stress, strain, and time observations were made of 10 solid cylinders of Solenhofen limestone compressed into the plastic range or beyond rupture; 32 observations were made of transient creep under nearly constant hydrostatic pressure and stress difference. Eighteen creep tests were made on Danby marble, Rutland White marble, and calcite, and 10 creep tests on the punching of Solenhofen limestone discs. A dimensionless strain ratio, t∈̇/∈ and a dimensionless stress ratio, (σz - σm)/σm, were found to be parameters respectively of fracturing and of ductility for limestone.