Intruded mass of igneous rock that forces apart two strata and forms a round lens-shaped mass many times wider than thick. The overlying layers are often pushed upward to form a dome. A classic development of laccoliths is illustrated in the Henry, La Sal, and Abajo mountains of southeastern Utah, found on the Colorado Plateau.
The disc represents the full moon, traditionally the most auspicious time for work and celebration. The disc is set towards the hoist. Effective date: 1 January 1981.