Dikes of the sheeted dike layer are conspicuously chilled against the underlying mafic and layered ultramafic rocks, indicating that the older rocks were relatively cool when the dikes were intruded. Cool mafic rocks could spread only by brittle fracture and infilling by dike material. Near-surface, cool ultramafic rocks could spread by brittle fracture or, possibly, by plastic deformation. The absence of significant infilling, and the preservation of cumulate textures in the extensive layering indicate that spreading did not take place.

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