Opportunities of radical breeds of sedimentary cover usage in St.-Petersburg as the basis of high-altitude buildings are considered in the paper in compressed form. Influence of a underground relief of a radical breeds roof of late Vendian, generated by buried bottomlands, on feature of an engineering-geological cut of the basis is analyzed. The generalized parameters of jointing and physic mechanical properties of top-kotlin clay of late Vendian and early Cambrian clay adjournment are resulted, allowing to estimate bearing ability of these soils. Recommendations whenever possible uses of various types of the bases depending on an engineering-geological cut are given.
