Chapter 7

Conservation of Mass and Momentum

One of the earliest block diagrams (see above) in the literature of structural geology (Argand, 1911) illustrates a part of the Penninic Alps of Switzerland and begs the question: how can we understand the processes that produce such ornate structures? In the title of a 1999 paper the authors of this textbook asked the related question: can we understand tectonic processes and their structural products without appeal to a complete mechanics? Our answer was, and is ‘no’. To address variations in velocity in 3D space and time we formulate in this chapter the governing equations of continuity and motion from the fundamental laws of mass and momentum conservation. Here we provide the links between concepts of calculus and physics taught in undergraduate courses and the concepts of continuum mechanics required to practice modern structural geology.

Exercises

Concepts from Chapter 7

These exercises explore concepts from Chapter 7 including reviews of particle dynamics and rigid body dynamics and statics, conservation of mass, linear momentum, and angular momentum in a deformable continuum, and the field equations for the linear elastic solid and the linear viscous fluid.