Why do some Northern Ural Mountains have flattened summits?

The Northern Ural Mountains feature flattened summits because they are the remnants of ancient peneplains—eroded surfaces of large areas and slight relief—that were subsequently uplifted by geologically recent tectonic movements.1

These summits represent a landscape that was once reduced to a plain of extremely low relief through long-term erosional processes before being elevated to their current heights. In the northern regions, these surfaces have been further modified by intensive weathering, which has created vast "seas of stone" across the mountain slopes and summits.12