Commune: Podgórzyn (pow. jeleniogórski, woj. dolnośląskie)
Framework element or context represented:
Element of erosional geomorphology on granite, a representative site for the Bohemian Massif.
Primary geological/geomorphological interest:
Granite dome hill with a rich assemblage of minor landforms due to weathering and mass movement
Comparative assessment justification:
A representative site of erosional relief developed on basement rock in Central Europe in pre-Quaternary times, exceptional in its variety of minor landforms. A textbook example of structure - landform relationship in terms of both form and process.
Protection status and accessibility:
Currently no protection status; easy access on a marked trail to the summit and footpaths across the slopes; an educational trail in preparation.
Character of site: Natural outcrops.
Area: c. 6 ha
Altitude: 400-484 m a.s.l.
Lithology: granitoids
Discipline: Geomorphology, Petrography
Process Age: Neogene, Paleogene, *all periods
Bedrock Age: Carboniferous, *all periods
Description of primary interest:
Witosza (484 m a.s.l.) is a dome-shaped hill (bornhardt) c. 80 m high located within a rock-cut hilly landscape of an intermontane Jelenia Góra Basin. In the vicinity there occur other granite hills, but rock outcrops on Witosza are most extensive. The hill is build of coarse-grained granite of Late Carboniferous age, typified by its large feldspars, up to 10 cm long, and cut by aplite veins in a few places. Fracture pattern includes an orthogonal joint set and widely spaced (1-3 m) sheeting joints superimposed onto the rectangular set, steeply dipping outwards. Geomorphology of the hill is strongly adjusted to the fracture patterns. The primary dome form is subject to degradation caused by gravitational opening of vertical and sheeting joints, the evidence of which are deep clefts parallel to the slope, fissure and boulder caves up to 18 m long, and extensive block fields in the lower slope. The effects of subaerial weathering include a ruiniform relief in the summit part and a variety of minor forms on rock outcrops such as weathering pits, karren, and tafoni. The origin of the hill is probably multi-stage and genetically related to repeated deep selective weathering mantle. Subaerial degradation of the dome took place mainly in the Neogene. The legacy of periglacial environment is obscure because of strong structural control. A few man-made modifications include widening of some clefts and building staircases leading to the summit.
Literature:
BORKOWSKA M. 1966–Petrografia granitu Karkonoszy (Polish only). Geol. Sudetica 2: 7-119. MIGOŃ P. 1992–Granite rock forms on the Witosza hill in the Jelenia Góra Basin - as the proposed inanimate nature reserve (English sum.). Chrońmy Przy. Ojcz. 48(1): 62-71. MIGOŃ P. 1993–Granite domical hills (bornhardts) in the Jelenia Góra Basin (English sum.). Czas. Geograf. 64: 3-23. MIGOŃ P., DACH W. 1995–Rillenkarren on granite outcrops, SW Poland, age and significance. Geografiska Annaler 77A: 1-9. MIGOŃ P. 2000–The origin of granite caves in Witosza Hill, Jelenia Góra Basin (English sum.). Kras i Speleologia 10: 143-154.