Obtoczenie i charakter powierzchni ziarn kwarcu w glinach zwałowych i piaskach morskich rejonów Dziwnowa i Zatoki Gdańskiej
Abstract
ROUNDNESS AND CHARACTER OF QUARTZ GRAINS IN TILLS AND MARINE SANDS IN AREAS OF DZIWNOWO AND GDAŃSK BAY
Summary
The paper presents comparative characteristics (roundness and surface structure) of quartz grains from tills and marine sands in Dzwinowo area and western part of the Gdańsk Bay (Fig. 1). Marine sands occuiring there are mainly the result of washing of tills. Analyses were made under stereoscopic microscope. Roundness of. grains was determined with the use of standard of Russel, Taylor and Pettijohn, and structure of surface - with the use of the L.B. Ruchin (1969) scale as modified by R. Kotliński and F.B. Pieczka, 1977), identifying grains with: 1) smooth - glittering, 2) rough - fine-rough, 3) cavernaceous, 4) corroded, and 5) high-relief surface.
The studies showed that in relation to tills the marine sands are improverished in angular and subangular grains with high-relief surface at the avantage of subrounded, rounded and well-rounded grains with rough, fine-rough surface. The range of these changes (Tables 1, 2) indicates that sands of the Gdańsk Bay originated directly from washing of tills, whereas grains of sands from the Dzwinowo area were seasonally subjected to reworking in eolian environment also.
In both areas, marine sands are characterized by much higher variability in roundness of grains between individual samples than the tills (Fig. 2, Tables 1, 2). This is mainly due to selection of grains, depending on their shape, in the course of their transport.
The obtained results show that it is not possible to establish grain types unequivocally typical of shallow marine environment of southern Baltic on the basis of the degree of roundness and structure of surface.
Summary
The paper presents comparative characteristics (roundness and surface structure) of quartz grains from tills and marine sands in Dzwinowo area and western part of the Gdańsk Bay (Fig. 1). Marine sands occuiring there are mainly the result of washing of tills. Analyses were made under stereoscopic microscope. Roundness of. grains was determined with the use of standard of Russel, Taylor and Pettijohn, and structure of surface - with the use of the L.B. Ruchin (1969) scale as modified by R. Kotliński and F.B. Pieczka, 1977), identifying grains with: 1) smooth - glittering, 2) rough - fine-rough, 3) cavernaceous, 4) corroded, and 5) high-relief surface.
The studies showed that in relation to tills the marine sands are improverished in angular and subangular grains with high-relief surface at the avantage of subrounded, rounded and well-rounded grains with rough, fine-rough surface. The range of these changes (Tables 1, 2) indicates that sands of the Gdańsk Bay originated directly from washing of tills, whereas grains of sands from the Dzwinowo area were seasonally subjected to reworking in eolian environment also.
In both areas, marine sands are characterized by much higher variability in roundness of grains between individual samples than the tills (Fig. 2, Tables 1, 2). This is mainly due to selection of grains, depending on their shape, in the course of their transport.
The obtained results show that it is not possible to establish grain types unequivocally typical of shallow marine environment of southern Baltic on the basis of the degree of roundness and structure of surface.