Geomorphological Features of the Area to Be Established as a UNESCO Global Geopark in Phu Yen

Abstract

The proposed area for establishment of Phu Yen Geopark is limited to 6 districts, towns and cities, including: Tuy Hoa City, Dong Hoa provincial town, Tuy An district, Song Cau provincial town and 3 communes, 1 town in Phu Hoa district town, 3 communes in Son Hoa district with an area of 1,575 km². Distributed in the central coastal line, the area's topography is quite diverse, including mountains, hills, plains and coastal areas, divided into 6 main origin types: 1) Terrain tectonics, volcanoes, architectural erosion, include: The tectonic and cavitation flanks of Pliocene - Quaternary age; Highland ridge, Neogene - highland Quaternary; Surface of the volcanic plateau has an elevation of less than 250 m; Surface of volcanic plateau is 300-400 m high; Cone ridge of Quaternary age crater; Structural eroded slope; Slope erodes edge of dome of the intrusive blocks, quartz fracture zones; 2) Terrain formed by erosion – cavitation, include: Pediple leveled surface, Miocene age 750 - 1100m high; Pediple leveled surface, early Pliocene age 450 - 600 m high; Pediple leveled surface, late Pliocene age 300 – 400 m high; Pediment leveled surface, Late Pliocene - Early Pleistocene age 150 - 250m high; Early - middle Pleistocene pedimen surface, 50 - 120 m high; Cavitation flank; Cavitation flanks of crevices and ditches of Quaternary age; Cavitation – erosion flanks; Collapsed erosion flank in Neogene - Quaternary age; Synthetic erosion flank Neogene - Quaternary age; Abrasion flank Quaternary age; 3) Terrain formed by rivers, include: River shelf level II, late Pleistocene age; River shelf level I, middle Holocene age; River accumulation delta, late Holocene age, early age; River bed and low alluvial ground along the riverbed, late Holocene age, late age; 4) Terrain formed by the sea, include: Abrasion – marine accumulation surface, Early – Middle Pleistocene age; Abrasive seashelf – accumulation level III, late Pleistocene age, early age; Abrasive seashelf – accumulation level II, late Pleistocene age, late age; Sea shelf level I, middle Holocene age, 5-10 m high; Surface of the sand dyke connecting the island, late Holocene age, early age; Modern beaches are flooded with frequent tides; 5) Terrain include:formed by the mixed impact of rivers and sea, include: The river-sea delta (shelf) of the Late Pleistocene age, Late and Middle Holocene age; Modern sea-swamp plain; Modern river-swamp plain; 6) Terrain formed by wind, include: Terrain type of sand dunes with elevation of 15-25 m; The terrain is sandy hill with an altitude of 105 m. Each terrain type is associated with diverse geological heritages: paleontological heritage; geomorphological heritage; stone heritage…