Source: Higgins, MD, Higgins R, 1996
Monemvasia is a small-scale example of the horsten and graben that you find all over the Peloponnese. The most important fault lines in the south of the Peoloponnese run NS, with secondary fault lines EW. Those EW fault lines form the horst of Monemvasia. The NZ fault line largely cuts the block off from the mainland. It is a huge block of dolomite that geologically connects with the stones just to the west, on the mainland of the Peloponnese.