3970617684

morphographical survey will also be reąuired to map the Pleistooene and Holocene sediments. Above all, due to Luxembourg and Belgium’s delimi-tation of the scope of the morphological survey there are many exclusive commissions possible, that necessitate certain scales of mapping and special eąuipment. This brings us to the following point:

III. The eąuipment, that the surveying morphologist has at his dispo-sal. Can he only (or nearly only) depend on his own sharp observations in the terrain, ad oculos? Or does he, so as Gerlach and Starkel from Klimaszewski^ school, perform important practical experiments over the amount of denudation, and materiał transport? Are there aerial photographs at his disposal? Or has he the use of a laboratory, where clay minerals, heavy minerals etc. can be investigated in different ways, as in Amsterdam? In many applied geomorphological investigations (Bakker 1960) and the allied geomorphological survey such aids are indispensable, at least if one appreciates an adeąuate advice and opinion. Functional applied geomorphology must not be allowed to run the risk that it misses the point, due to insufficient eąuipment.

Klimaszewski has rightly shown that the morphological map should contain a piece of morphogenetical interpretation, if only because pre-cisely this part of the morphological survey works as such a stimulous for the investigators. But in certain forms the clay minerał composition of the materiał is the most dominant factor in the explanation. For example, in boulder clay earth pyramids may be found, which contain about 15-30% clay < 2 mu, and are formed from about 70-80% illite and 10-20% montmorillonite (discussion Becker, Hollermann and Bakker, Symposium on Slope Development, Góttingen, August 1962). The valley pattern in a loess landscape by Kasimierz (Lublin region, Poland) mapped by K ę s i k , is indeed very characteristic, but differs from everything in West European loess regions. Probably here the reason for the above differences lies in the greatly varying clay minerał composition of the Southeast European (an high, or at least noticeably higher percentage of montmorillonite) and the Middle- and West-European loess regions (almost entirely illite loess) and the related differences in the permeability, the liąuid limit and the plasticity. Professor J. D e m e k also pointed out the great differences in geomorphological habitus of loess landscapes in the East and West parts of Czechoslovakia to me (Symposium on Slope Development — Góttingen 1962). Can here the explanation perhaps be that Professor K a d a r (Debreczen) understands under the term loess something ąuite different than is usually under-stood in West Europę?² It also seems not improbable to me, that the fine suffosional forms showed by C z e p p e as well as those in the loess from Lublin, are defined by a special hydro-lithological relation-ship, in which the grain size freąuency and the clay minerał composition play an important part.

The morphological survey will further also be intensely occupied with the soil erosion phenomena, which now, sińce the removal of forests, play an important part in so many areas, for example, in connection with planological objectives, foundation of houses on mountain slopes, etc. One then freąuently encounters soil mechanics ąuestions, which are

^! At present the most Westerly found loess with a high montmorillonite content (about 50%) seems to be at Gaustadt near Bamberg. See G. Hohl (1958 and 1959).

15