Publication details
Písečník Hill at the Rychleby Mts. foothills (Sudetes Mts.) - the first described drumlin from Czechia
| Authors | |
|---|---|
| Year of publication | 2013 |
| Type | Article in Proceedings |
| Conference | XX Konferencja Stratygrafia plejstocenu Polski Plejstocen przedpola Sudetów Środkowych Lasocin, 2.-6. 09. 2013 r. |
| MU Faculty or unit | |
| Citation | |
| Field | Geology and mineralogy |
| Keywords | lodgement till Miocene bedrock boulder lag supraglacial sediments ice-cored (hummocky) moraines part bedrock/part till drumlin Rychleby Mts. foothills clast petrology and provenance |
| Description | Písečník Hill (288 m a.s.l.) is an isolated elevation located near the Javorník Town close to the NE foothill of the main ridge of the Rychleby Mts. It has a shape of a ridge elongated in the NE–SW direction, made of compacted Miocene sands covered by Pleistocene tills and glaciofluvial sediments. Glacial sediments represent succession of subglacial sediments at the bottom followed by supraglacial sediments in a direct superposition. Subglacial sediments consist of two units - lodgement till with boulder lag on base and infill of shallow depression in subglacial lodgement till. Subglacial sediments are monotonous from petrological point of view with a clear predominance of local rocks (mainly of Gierałtow gneiss). Supraglacial sediments are better sorted and more variable from facies point of view (boulder gravel, wavy-laminated sand and cobble-boulder gravel). Supraglacial sediments consist diversified material. Clats originating from the entire vertical profile of an ice sheet margin, which has totally different transport history and characteristics is deposited in supraglacial environment. Písečník Hill has a steep side facing towards the NE and a gentle sloping side oriented towards the SW. This elongation has been caused by the ice sheet advance direction. The elevation core is made of relatively compact, but unlithified pre-Quaternary bedrock, on which subglacial lodgement till has been deposited. According to these features we can interpret Písečník Hill as a part bedrock/part till drumlin (Stokes et al. 2011). The surface was cracked by transverse fissures during the ice sheet movement over the elevation. This was followed by a gradual ice sheet front decay, during which ice-cored moraines evolved. Variable supraglacial sediments overlying lodgement till and subglacial cavities infill remained at this place after the complete melting of the ice sheet. |