Final answer:
Arching action in masonry walls involves the use of arches, which transfer the load into compressive stresses. The corbel and true arch are examples of this architectural technique, allowing for greater spans, stability, and aesthetic design within buildings.
Step-by-step explanation:
Arching action occurs in a masonry wall when it employs the architectural feature known as an arch. The arch is an element that, through its shape, can support weight by transferring the force of the load into compressive stresses carried into the ground. A classic example of arch application lies in the corbel arch, used by Mycenaean architects, where stones are laid so that they incline slightly towards the center at higher courses until they meet at the apex.
The innovation led to the creation of impressive structures like Roman aqueducts, which combined utility with aesthetic appeal through the use of arches. Another evolution in arch design was the true arch, characterized by wedge-shaped voussoirs and a central keystone, which allowed for greater spans across distances, contributing significantly to architectural longevity and stability, exemplified by structures like the Colosseum.