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Geology / Relief

Geology / Relief

A distinctive feature of Rila Mountain is its massive character, emphasized by the fact that almost everywhere it is surrounded by valleys. At the same time, due to the deep incision of the valleys of the rivers Beli and Levi Iskar, Rilska, Iliyna, Blagoevgradska Bistritsa and Belishka, it is divided into four clearly separated parts: Eastern, Central, Northwestern and Southwestern.
Parts of the four Rila sections fall within the National Park. Eastern Rila has the largest area (45.1%). In second place in terms of area in the park is Northwestern Rila (21.5%), which is only slightly ahead of Southwestern Rila (20.7%). The smallest part of the park area is located in Central (Middle) Rila (12.7%), which is due to the fact that a large part of it is included in the Rila Monastery Nature Park.
The territory of Rila National Park falls within the scope of the Alpine orogenic belt, and more precisely in its inner parts. Therefore, this area has all the typical features of highly metamorphic complexes built of rocks formed at great depths in the earth's crust (over 25 km). Rila's position in the Alpine orogen is clearly defined. The mountain is considered as part of the Rhodope tectonic zone, located south of the Marishka seam, which separates it from the Balkanids.
The presence of the three classes of rocks is established within the Rila National Park and its nearest periphery: metamorphic, magmatic and sedimentary. Metamorphic rocks are the oldest and include both metamorphosed sediments (shale, paragnais, marble) and metamorphosed magmatic rocks (gabbro, basic volcanics; metamorphosed granites converted into orthognases, etc.). Metamorphic rocks contain younger magmatic rocks of different sizes. Some of these magmatic bodies are huge, such as the Rila-Rhodope batholith. Metamorphic and magmatic rocks are traditionally combined and characterized as a crystalline substrate or foundation. Sedimentary rocks are represented by various continental-type sediments formed in lake and river environments that are younger than the crystalline basement.
Due to the significant hypsometric range and the diverse landscape conditions that exist in the Rila Mountains, on the territory of the national park there are relief forms, a product of various morphogenetic processes. Some of them are the result of the action of processes that operated in the past, other processes continue to shape the appearance of the mountain today, and others in the past have formed the morphosculpture in a different height of the mountain belt.
Today on the territory of Rila Mountain, as well as in the scope of the park, the following genetic types of relief are widespread: glacial, periglacial, planar, fluvial and gravitational. The most expressive and most common forms of the relic glacial morphological complex are the circuses. They are a negative armchair with steep slopes and a sloping bottom, often occupied by one or more lakes. In the Northwestern Rila the circuses have mainly northern exposure. Such are the Kalinski, Otovishki, Skakavishki, the circus of the Seven Lakes, the Urdini, the Malyovishki and others. In other parts of Rila, circuses with southern (Redzhepsky, Vapsky, etc.) or eastern (circuses between Malak Mechi Vrah and Ezernik in Southwestern Rila or Ibar and Ropal in Eastern Rila) predominate. The highest circus is that of the Ice Lake below Mount Musala. Other characteristic forms are carling and sheep humps. Carlings are sharp, often jagged tips that form on the watershed between circuses.
The periglacial relief is widespread in the Rila Mountains above about 2000-2100 m above sea level. less known Unlike glacial relief, which is extremely relict, periglacial relief is also the result of modern morphogenesis. One of the most characteristic forms are the rock glaciers. They are positive relief forms, representing an accumulation of rough, unpolished rock blocks in the form of a tongue filling the valley or a series of shafts at the base of the slope.
The planetary relief is associated with the stages of tectonic dormancy, during which exogenous earth forces denuded and leveled the territory, turning it into an almost flat area. During the subsequent tectonic activity it breaks and remnants of it can be found on the wide ridge plains and sloping steps. In this sense, this type of relief in Rila is extremely relict. This type of relief is widespread in the Kapatnitsa part of Rila.