This article aims to present the results of geotechnical studies of the main rock complexes that compose the periphery of the Dobrudzha Plateau in the area from Cape Kaliakra to Cape Shabla (Bulgarian Black Sea Coast), directly related to the development of hazardous geological processes. Sediments of the Sarmatian age were studied: carbonate tempestites, Mactra limestones (Karvuna Formation), nubecular (foraminiferal), reef and bioclastic limestones (Odartsi Formation). The corresponding microscopic and petrographic analyses of the studied sediments are also presented. Studies of collapses in caves near Cape Kaliakra show that they occur in friable peloidal limestones, with disturbances following stratification. This is confirmed by laboratory tests of samples showing lower strength indicators, namely in the direction to the layering. The results of laboratory tests of specimens from the sections between the village of Tyulenovo and Cape Shabla, including foraminiferal, reef and bioclastic limestones, show higher values of physical and mechanical parameters compared to limestones at Cape Kaliakra. In the case of the bioclastic limestones, higher strengths are found crosswise to the layering, and in the case of compressive strength, the ratio is double. The obtained data provide valuable information about the engineering geological parameters of the main varieties in which the rock deformations are developed, which can be used in the analysis of slope stability.

This study presents the results of 227 tested specimens of the Sarmatian age taken from the rock complexes that build Kaliakra Cape: these are carbonate tempestites, as well as the limestones from the Karvuna Formation lying above them. Sedimentological and geotechnical tests have been performed.  The micropetrographic analysis of the carbonate tempestites is also presented, including slightly consolidated conglomerates and hard limestones between them. It was found that the matrix of conglomerates is composed mainly of micritic peloids. Their size is about and below 0.2 mm. No cement is found, which is why the porosity is significant. Peloidal limestone has low values of bulk density -- an average value of 1.95 g/cm3. There is a significant difference in compressive strength and velocity of seismic waves obtained in both directions -- crosswise and parallel to the layering.  Studies of collapses in the caves in the area show that they occur in friable peloidal limestones, and the disturbances follow the formation. This is also confirmed by the laboratory tests of samples showing lower strength indicators, namely in the direction of the layering. The data thus obtained provide valuable information on the geotechnical parameters of the main varieties in which the rock deformations are developed, which can be used in the analysis of slope stability.