concretion
![chalk-flint concretions](../../images/chalk-flint_concretions.jpg)
Chalk-flint concretions.
A concretion is a hard, compact, irregularly-shaped nodule of rock embedded in sedimentary rock of a different composition, in which it grew by deposition on a nucleus. Examples include flint in chalk.
Chalk-flint concretions.
A concretion is a hard, compact, irregularly-shaped nodule of rock embedded in sedimentary rock of a different composition, in which it grew by deposition on a nucleus. Examples include flint in chalk.