The paleokarst occurrences associated with Lower Carboniferous limestones in the east of the Middle Urals are considered. We analyse the nature of the Early-Middle Carboniferous boundary. We argue the absence of a long break at the end of the Early Carboniferous in the Middle Urals. Uplifts were in blocks and quickly destroyed. It's most likely that karst is Meso?oic in age. Probably, two types of its manifest related to different mobility of underground waters that filled karst caverns after their formation.
