One of the area’s interesting geomorphological features are the numerous block deposits on the summit of the Beigua massif, which have always been attracting the interest of hikers and researchers. In the past, geologists have already described these large block deposits (Issel A.1892; Sacco F. 1934; Conti S. 1940). Several studies ensued, with the purpose of understanding their origin (gravitative, glacial or periglacial) and how they originated and moved.
According to recent studies, the structures and morphologies of several deposits are similar to those of “blockstreams” that are currently forming in periglacial areas.
Within the Geopark, two types of deposit belong to this category: blockstreams and blockfields. Blockstreams are situated on slightly sloping grounds (8° - 12°), their shape is elongated, and they are commonly found along a ridge’s most inclined section or, in the majority of cases, along a wide valley floor; blockfields are instead situated in roughly flat areas, and their shape is less elongated.
Two further characteristics of blockstreams are “rock lobes”, aligned both along the deposit’s stretching direction and athwart, and compression structures in the deposit’s lowest part, showing the direction of the movement that these rocks underwent. The surface of these deposits consists of boulders whose diameter is almost always larger than 60cm, without fine material (gravel, sand, or clay) in the interstices; along the deposit edges, blocks are tabular in shape and placed either vertically or inclined by more than 30°.
Identifying the origin of these deposits as periglacial is especially important in order to define the climate boundaries during the last ice age.
A clear example of these deposits can be observed at Torbiera del Laione, above the hamlet of Piampaludo (Sassello).