This study presents a review on Holocene glacial traces in Bulgaria. Pleistocene glaciation in this territory was spread over a number of mountains above 2000 m a. s. l., while in the later time, it was restricted only to the highest areas of the two highest mountains, Pirin and Rila. Two major phases can be distinguished on the basis of field evidence-a Little Ice Age (LIA) phase, and a present-day phase. Features of present-day glaciation are only found in the Pirin Mountains, in the highest parts of Northern Pirin which are built of carbonate rocks (marble). The two glacierets in these mountains, which are now the southernmost glacial masses in Europe, occupy only c. 1.5 ha. Several permanent snow patches are also found to fill the bottoms of high altitude karst dolines in the same area, contributing to a total of 3.5 ha of firn and ice, which have not completely melted for several centuries. The post-LIA climatic warming, which has progressed with an increased pace for the last 3 decades, reduced the glaciated area in the highest mountains of Bulgaria by 58%. However, glacierets and snow patches in Bulgaria have appeared to be more stable when compared to most other locations with similar topographic setting in Southeastern Europe.

The present article is focused on high mountain relief in marble, which combines glacial, periglacial and karstic morphology. High mountain karst is found in Northern Pirin (Vihren and Sinanitsa area) and central Pirin (Orelek area), the latter lacking traces of glaciation due to its low altitude. In the most representative area, Vihren part, several vast and deep cirques-uvalas were formed, which comprise a large diversity of landforms. Main factor for the specifics of relief in marble is the structure of the rock, which combines carbonate mineral content and crystalline properties; they favour both the occurrence of karstification and frost weathering. The high elevation of Northern Pirin (up to 2914 m a.s.l.), and the resulting extensive former glaciation enhanced the karst processes by weathering of the morphological surface. At present, surface karst is most developed on elevated sections of cirque bottoms, which were ice free before the beginning of the Holocene and are away from rockfall creep accumulation. A special element of glaciokarstic relief in Pirin are the summer lasting snow/ice features (glacierets and snow patches), two of which are considered centuries old, and still survive despite the temperature warming. In general, karst processes in the high mountain areas of Pirin are less developed than in the western part of the Balkan Peninsula (the Dinarides), due to the greater susceptibility of marble to physical weathering compared to limestone, which leads to a more intensive formation of regolith on the surface, and in result of the generally colder and dryer climate.