Sabatini complex

The Monti Sabatini are a geologic region in Lazio, central Italy, a remnant of intense volcanism which started ca. 600,000 years ago, mainly with pyroclastic and maar forming eruptions which continued until 100,000 years ago. They are part of the Lazio's Anti-Apennines. Included between the Monti Sabatini is the Lake Bracciano, which is a volcanotectonic depression formed about 3.7 Ma, and the Lake Martignano. The sedimentary base of the Sabatini complex lies buried under 200 m (660 ft) of volcanic ash and rocks.

• http://en.wikipedia.org/wiki/Sabatini complex