Cineritele de la Somușca, Bacău, Nature reserve in Cleja, Romania

Cineritele de la Somușca is a 0.10-hectare geological reserve on the southern slope of Pătul Hill, south of Cleja. It protects andesitic ash layers and large andesite blocks interbedded with Meotian sediments. The cemented ash forms grey-blue banks that begin mid-slope and end in a 40–50 m rocky face below the summit.

The Romanian government protected this area as a natural monument in 2000, acknowledging its geological value for scientific study. This official designation helped safeguard the volcanic tuff layers from further erosion and quarrying activities.

The reserve functions as the endpoint of Căii Sfintei Cruci hiking trail, where visitors observe and study the geological formations of eastern Romania.

Access is via marked trails from Cleja village, with the best views of the rock formations available during daylight hours in warmer months. Visitors should wear sturdy footwear since the paths cross uneven and sometimes steep terrain.

The andesitic ash beds at Pătul Hill contain magnetite and altered feldspar grains, and geologist Sava Athanasiu first noted them at Cleja in 1908. Some researchers argue the lava fragments could not have been wind-blown from the Harghita or Baraolt mountains, since the Carpathian ridge was already raised in the early Pliocene.