Composition of the deep-seated Inclusions of ultrabasic and basic rocks in kimberlites and basalts is correlated with the type of construction of the crust. We suggest that these inclusions reflect the composition of the lower horizons of the crust and the top of the mantle, and that ktmberlite was originally a gassaturated tectonite, developing on the boundary between mantle harzburgite and. the lower horizons of the crust (the Mohorovicic geophysical surface). This surface is probably one of the principal tectonic planes during the displacement of continents. Geological analysis suggests that the deep-seated inclusions in kimneriites are rocks from the base of the crust of the Precambrian metamorphic blocks. This once again makes it possible to the raise the question of the interpretation of the diamond occurrences in the rocks of the deep Precambrian. —.Authors.