( 215 ) 



about one lieclaro, and 2 or 3 M. altoNc llic l)asis of the sand and 

 gravel deposit: A lai-ge honldev oi' ThoH,.sc/u('/('r, of i.l^ö X 0.75 X 0.35 

 ÏM., and three smaller ones, of about 0.5 M. greatest dimension, a 

 boulder of veined gray quartzite, of 0.80 X 0.75 X 0.50 M., 

 another gray quartzite of 0.67 X 0.36 X 0.20 U., a flint nodule of 

 0.60 X 0.35 X 0.15 M. Other large stones were knocked into [)ieces. 

 East of Belfeld boulders are not so frequent in llie gravel. Amongst 

 others I observed there a basalt of about 0.40 M. largest dimension. 

 From these obserxations we are led to sujipose a transport on a 

 large scale by floating ice, and we can imagine that ice having 

 had its origin, in the upper-course of the llliine and the Meuse, from 

 bottom-ice. The basal part of the deposit, 2 M. thick east of Tegelen, 

 5 M. thick east of Belfeld, is, however, entirely devoid of pebbles, 

 it consists of rather fine sand. 



All this induces us to consider this "Rhine-diluvium" as a glacio- 

 flnvial formation of the lirst Pleistocene Glacial epoch, chronologi- 

 cally the equivalent of the tluvioglacial Deckensdiottei' of the Dilu- 

 vium of the Middle-Rhine. 



This interpretation is now affirmed by the character of the bed 

 underlying the gravels and sands in the [)lateau in consideration. Save 

 gravel and sand there is dug clay, which furnishes the material for 

 the many tileries and stone-factories, in a great number of places, 

 of the Netherland province of Limburg and of the adjoining region 

 of the Rhine-Province of Prussia, chiefly on the borders and along 

 the transverse valleys, of the .Swalm, etc. That clay is lying confor- 

 mably and with not eroded, rather well horizontal separating plane 

 under the "Rhine-diluvium", the equivalent of the Decli'nscJioth'r. 

 Her own planes of stratification are also generally horizontal. In the 

 clay-pit of the well-known stone-factory of the lii-m Canoy-Herfkens, 

 on the western border of the Jammerdaalsche Heide, her upper surface 

 is at 27 M. -[- A. P. East of Belfeld, near Maalbeek, 4.5 K.M. S.S.W., 

 1 found that surface at 35 M. -\- xA..P. East of Reuver and 8.5 K.M. 

 S.S.W. of the i)it opposite Tegelen, it is at 43 M. -f A. P. East 

 of Swalmen, near the Dutch (yustom-house on the frontiei', 14 K.M. 

 south-west of Ihe pit in llie .lammerdaalsche Heide, il is at 50.5 -|- A. P. ^) 

 The same clay is also dug roundaboiil Briiggen, on the Swalm, in 

 the Rhine-Province, 5 to 8 K.M. east of the pit near the Custom- 

 house. It is probably also the same clay, which is met with, at the 

 surface, east of the Zwai-twater, (north (»f \'culo), and west of the 

 plateau, in the couiunmes of Tegelen, Belfeld Bcuvcr. 



Evidently this clay constitutes a conliniious bed underlying the 



1) 111 the Diilcli Lc'xL of this toiuniiiiiicaliuii llie iilliliulos ucio only cstinialeil, in 

 this engiisli versiuii they are given from exact determiualions by levelling. 



