Observations are presented of the OMC1 Ridge (a narrow band of molecular gas containing high-mass embedded sources), in the transitions CN N = 2 - 1, 13CO J = 2 - 1 and 13S J = 5 - 4. Variations in velocities and line widths indicate that three distinct regions are present in the area mapped, and that at least one of these is rotating. The resulting shocks when these fragments collided will have compressed the gas to a density nH2~107-8cm-3, sufficient to trigger collapse and to explain the presence of high-mass stars at the edges of the cloud fragments, rather than in their cores. These observational results support theoretical predictions of the importance of collisions in star formation
