This text investigates the formation, structural characteristics, and petrological evolution of layered igneous intrusions. The authors, L.R. Wager and G.M. Brown, utilize their extensive field research—most notably from the Skaergaard intrusion in Greenland—to establish a comprehensive framework for understanding how magma chambers crystallize and differentiate over time. They argue that the layering observed in these formations is a direct result of gravitational settling and convective processes within cooling igneous bodies.

Experts recognize this work as a foundational text in the study of igneous petrology and magmatic differentiation. Readers frequently note the technical density of the prose, which assumes a high level of prior knowledge in mineralogy and geological chemistry.