The interesting thing about walling is that within the physical universe as we know it, (even reduced to the simplest of disciplines, that of humbly laying only stones upon stones so as to maximize their connectivity) there are fundamental disagreements amongst walling experts as to how it is to be done. You would think by now people would have reached a universal consensus discussing such things as basic to walling as...
- coursing versus non-coursing (random) and also diagonal patterns
- slight outward versus inward leaning of individual stones in a wall
- graduation of sizes of stones from top to bottom
- imperative requirement of throughstones
- type and depth of foundation
- existence and degree of batter
- shaping stones versus not shaping
- most practical style (flat or vertical) , and lean (or not) of coping
- specifications concerning the thickness and proper construction of dry stone retaining walls
Even accounting for variations of rock types and geography there are still many differences of opinion about how the science of walling is to be understood. Apparently even after thousands of years of fitting stones together we can't agree. All over this stoney planet there are so many examples of differing styles, and differing explanations for the principles at work, that 'breaking down' why certain piles of stone stones 'stay up' better than others, still remains very much a mystery.