Strain weakening during plastic deformation can be achieved via strain energy reduction due to intragranular boundary development and grain boundary formation. To examine intragranular boundary formation at high temperatures (T_h≈0.9), we analysed electron backscatter diffraction (EBSD) data of coarse-grained ice deformed at -30°C. Misorientation and weighted Burgers vector (WBV) statistics were calculated along planar intragranular boundaries. Neighbour-pair and random-pair misorientation distributions intersect at misorientation angles of 10–30°, indicating an upper limit to the misorientation threshold angle at which neighbouring grains begin to interact, e.g., rotate relative to each other. Misorientation angles change markedly along each analysed intragranular boundary, linking low- (<10°) and high-angle (10–38°) segments, with each segment exhibiting distinct misorientation axes and WBV directions. We suggest that these boundaries might be produced by the growth and intersection of individual boundary segments comprised of dislocations with distinct slip systems. This new kinematic model does not require a change in the boundary geometry after its formation, as required by the other models, to modify the crystallographic geometry of a planar boundary. Misorientation axis distributions are fundamentally different between intragranular boundaries (mostly confined to the ice basal plane) and grain boundaries (largely dispersed). This observation suggests a strong crystallographic control of intragranular boundary development via subgrain rotation. The apparent lack of crystallographic control for grain boundaries, on the other hand, suggests that misorientation axes become randomized upon grain boundary formation, likely due to the operation of other mechanisms/processes that can modify misorientation axes.