The processes of alteration and the degree of billing of the rocks are factors conditioning to the occurrence of falling of blocks. In this way, the fracture characteristics of the volcanic lithologies were studied together with the ascent of the mountain range, BR 158, in the municipality of Santa Maria, RS.
For the acquisition of data, the Scanline method of BRADY & BROWN (1985) was used. The obtained data were analyzed through vectorial statistics. The main groups of defined fractures are associated with the cooling of the rock and are represented by the average attitudes: Group 1: 348; 83; Group 2: 174; 82; Group 3: 85: 86; Group 4: 265; 75; Group 5: 300; 42 and Group 6: 121; 53.