The river continues through a deep, sparsely populated valley, and turns south near Trikorfo.

However, in the Miocene (23-5 Ma) another geologic regime began, the extensional, as part of a process called back-arc extension.

In addition to causing the main fault, the stress of extension relieved itself over a number of smaller approximately parallel subfaults within the Corinth Basin and to the north of it.

To create it, a simple earthen embankment was placed across the Mornos River in Central Greece at 38°31′37.1″N 22°07′14.7″E / 38.526972°N 22.120750°E / 38.526972; 22.120750.

The fact that the dam is located in a region of high seismicity causes some concern and results in a higher level of monitoring.

[6][7] The Mornos aqueduct is the sole conduit of water extending the entire distance from the reservoir to the processing stations of north Attica.

That distance is 110 kilometres (68 mi), which is not exactly straight, but curves generally to the south and is positioned to take best advantage of the terrain.

Due to modern tunneling machines and laser measurement devices no mountain is beyond the capability of the engineers.

For example, the Mornos aqueduct crosses the Pleistos valley at Delphi, but none of it is observable to the visitor, as it is deep underground.