Morfogeneza sieci rzecznej obszaru woj. bialskopodlaskiego w nawiązaniu do prawdopodobnego przebiegu deglacjacji
Abstract
MORPHOGENESIS OF A FLUVIAL PATTERN IN THE BIAŁA PODLASKA DISTRICT IN CONNECTION WITH A PROBABLE COURSE OF DEGLACIATION
Summary
In 1978 - 1987 the author team carried through geologic investigations in the area of the Biała Podlaska District. Relations in occurrence of gravels from origin and lithology of geomorphologic units constituted the main subject of these studies whereas development of fluvial pattern was found to be the key process in evaluation of the morphogenesis of this area. The authors accept that the landscape of the investigated area has been formed due to areal deglaciation of the last ice sheet in this region. Further denudation processes and fluvial erosion have been of secondary significance for development of this landscape. Areal deglaciation at relatively plastic substrate (Tertiary deposits and chalk) enabled uplifting of elevations from the bedrock. After the last dlead ice blocks had melted, a fluvial pattern system got inversed.
A fluvial system developed syngeneticaly with the progressive deglaciation. At first glacial rivers flew in wider and wider crevasses• and deposited sandy-gravel alluvia at various hypsometric levels. These alluvia were frequently uplifted due to static loading by ice blocks. At present they are visible in the landscape as small elevations within accumulation plains and have been named the buried james.
Predominance of areal deglaciation, development of vast flood plains, have not forced a development of ice marginal streamways and construction of end moraines of the Warta Stade in this area.
After dead ice blocks had melted, the fluvial outflow organized along thaw depressions. The present river valleys are the youngest landscape element and form a system of connected thaw depressions in which lake and ice-dam lake deposition predominated. Typical fluvial deposits form only narrow dams that are surrounded by lake sediments.
Summary
In 1978 - 1987 the author team carried through geologic investigations in the area of the Biała Podlaska District. Relations in occurrence of gravels from origin and lithology of geomorphologic units constituted the main subject of these studies whereas development of fluvial pattern was found to be the key process in evaluation of the morphogenesis of this area. The authors accept that the landscape of the investigated area has been formed due to areal deglaciation of the last ice sheet in this region. Further denudation processes and fluvial erosion have been of secondary significance for development of this landscape. Areal deglaciation at relatively plastic substrate (Tertiary deposits and chalk) enabled uplifting of elevations from the bedrock. After the last dlead ice blocks had melted, a fluvial pattern system got inversed.
A fluvial system developed syngeneticaly with the progressive deglaciation. At first glacial rivers flew in wider and wider crevasses• and deposited sandy-gravel alluvia at various hypsometric levels. These alluvia were frequently uplifted due to static loading by ice blocks. At present they are visible in the landscape as small elevations within accumulation plains and have been named the buried james.
Predominance of areal deglaciation, development of vast flood plains, have not forced a development of ice marginal streamways and construction of end moraines of the Warta Stade in this area.
After dead ice blocks had melted, the fluvial outflow organized along thaw depressions. The present river valleys are the youngest landscape element and form a system of connected thaw depressions in which lake and ice-dam lake deposition predominated. Typical fluvial deposits form only narrow dams that are surrounded by lake sediments.