Final answer:
Material deformations such as splits, checks, and warping are primarily caused by changes in moisture content, which lead to uneven shrinkage or expansion within the material.
Step-by-step explanation:
The issue in question is primarily caused by moisture content. When wood or other similar materials lose or gain moisture unevenly, it can result in various forms of warping such as splits, checks, crooking, twisting, and cupping. These deformations occur because different parts of the material may shrink or expand at different rates due to the differing moisture levels.
As the material's moisture content changes, which can happen due to various environmental factors, stresses build up internally due to the material trying to maintain equilibrium with its surroundings. Over time, these stresses can cause the material to deform. The extent of these deformations can be influenced by the material's composition, but the driving factor that initiates these changes is the fluctuation in moisture content, not the structural grading or external temperature fluctuations per se.