According to WRB (World Reference Base for Soil Resources)[39] andosols are dark soils with high organic matter content formed on young volcanic rocks. Their characteristics are determined primarily by allophanes, imogolite, ferrihydrite and Al/Fe-humus complexes. Their macro-structure is very loose with low value for volume mass, thixotropy, high cation exchange capacity and phosphorous retaining capacity are characteristic for them.

Geographical distribution, upper and lower limits of andosols in Romania are still to be made clear. Limited publications give controversial data in relation to the latter. Their appearance on maps published in recent years is controversial and hard to interpret especially in the cases of the Harghita and the Gurghiu Mountains. According to Romanian pedological literature andosols can be found above 1200 m asl, however, on soil maps of the scale 1: 200.000 [35, 36, 37] covering the Calimani-Gurghiu-Harghita volcanic chain as well they extend up to only 1500 m.