|The locations , mentioned in the text|
Some images ( compilations) from the large Kempen fan gravels depositions of the Maas river during the Cromerian periods ( ca 850.000 BP - 420.000 BP). Up to 20 meters of gravels, loam, coarse sands have build the west- upper terrace of the Maas -river, visible here in the S.B.S. pit [ community of Maasmechelen, Belgium] (click to enlarge)
Notice the upper red horizons being the lower part of the integrated As paleosol with an assumed Holsteinian date, ( between 420.000 BP - 360.000 BP ) the top horizons are already dug out.
After the Elsterian glacial the Maas river cut itself in the landscape, in the same period, the Kempen Plateau was 'created' by "inverted topography" as the soft Miocene sands were eroding. leaving the gravel plateau up to 50 meters in the surrounding landscape.
|Image above taken at Geological wall, community of As|
Below: Clay layers are formed by the river, during interglacial conditions. Such layers are impermeable and could cause chemical reactions in the bedrock during sub- tropical conditions, thus weathering the soil and producing iron -, aluminum- and manganese- oxidations.( Image: ASAC collections sample) This is a non stained, non- oxidated example from the SIBELCO pit at Maasmechelen.
(Above) Small geological insight of the Pleistocene Maas river at Bemelen (NL). Top -horizons show eroded loess, leached loess and gravel layers. The direction ( southeast - northwest) of the pebbles during deposition in the early Pleistocene is suggesting the Maas river made a large bend towards the east, ( eroding bank) , leaving the city of Maastricht at the depositional riverside.
|The Kikbeek -pit near the village of Opgrimbie is a grateful geological monument, showing in present times Pleistocene processes of gully- forming on eroding surfaces|
|Exposed surfaces without any vegetation are the beginning of the development of surface drainage systems such as gully's , caused by heavy erosional processes.|
The top horizons, like for example in the former Kikbeek- pit, show large differences in Pleistocene geological elements , depending on local circumstances. The three pictures below were taken from the same local stratigraphy, over a distance of ca 15 meters.
|(1) Developed oxidation horizons alternating with coarse sands|
|(2) west Manganese oxidation (in black) between sand - horizons|
|(3 ) west Unsorted gravels below a bleached top horizon|
|Prehistoric man most probably never saw the lignite ( black) and Micocene sand-covers (white) that are exposed here at the shore of an artificial lake in the former Kikbeek- pit near Opgrimbie (B)|
For more geological information see the website on regional geology of ASAC
AGC (argeocol.hpage.com); website is under construction
Michael A. Summerfield Global geomorphology , an introduction to the study of landforms Longman | april 1991
Judson Kauffman Leet Physical geology; Prentice-Hall 1987
River Systems: Process and Form Compiled by Jeff Crabaugh at Carleton College (SERC) and the University of Wyoming: sediment transport movies
ENFIA Natural History Geoarchaeology ( The Eldorado National Forest Interpretive Association)