Break-off slumping in Ordovician sedimentary deposits on the Lena-Angara Plateau

Characteristics of the break off of slump blocks consisting of sandstones of the Iiskaya Ordovician formation are considered. At definite stages of slope development, the blocks were slipping down the horizon of interlaminated banded aleurites, marlstones and sandstones of the upper subformation of the Ust’-Kutskaya Ordovician formation with a decrease in their strength under the effect of agents of physical weathering. It is found that the last stage of slumping intensification came to a close in the Early Holocene in connection with a decrease in the atmospheric precipitation amount during the summer period.