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4.1.2. Gembloux Formation


Authors: P. Haesaerts, S. Pirson & E. Meijs - 07/12/2011

Description: The upper loesses are better preserved than lower loesses; they are spread all over Middle Belgium, reaching locally up to 15 m thickness on plateau. The sediments are either calcareous loess, in situ or reworked along the slopes, or decalcified. Several interstadial palaeosols are distributed through the whole formation. Several tundra gleys also occur as marker horizons. The upper part of the formation is affected by the pedogenesis of the Holocene Luvisoil.

Stratotype: Harmignies (Omya Benelux and CBR chalk quarries; respectively at 50°25'08''N / 4°00'35''E and 50°25'13''N / 4°00'56''E).


- Eben-Emael (western wall of the CBR chalk quarry at Romont; 50°47'27''N / 5°38'37''E);

- Kesselt (Nelissen brickyard quarry; 50°50'13''N / 5°37'12''E);

- Veldwezelt-Hezerwater (western wall of the ancient Vandersanden brickyard quarry; 50°51'20''N / 5°38'24''E);

- Rocourt (ancient Gritten sand pit; 50°40'07''N / 5°33'45'' E).

Area: Middle Belgium, on plateau and slopes.

Age: Covers the whole Upper Pleistocene with the exception of the Rocourt Pedocomplex (i.e. MIS 5a pro parte to MIS 2) (Haesaerts, 1974; Haesaerts et al., 1997; 1999; Frechen et al.,2001; Pirson et al., 2009).

Remarks: Synonym: A-loess of Meijs (2002, 2006). Equivalent to upper part of the "Gembloux Formation" sensu Gullentops et al. (2001) (see Fig. Y), defined after the loess sequences described in the Gembloux area by G. Manil in the late 1940s-early 1950s and by R. Paepe in the 1960s (see Paepe, 1967; Paepe & Vanhoorne, 1967, 1976).