310 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 19, 



A. 



Rupelmonde. 



Thickness. 

 Feet. 



1. Yellow crag 15 



2. Rupelmonde clay, with 



LedaDeshay€siana,&LC. 90 



3. WMte sands (Middle! , c 



Liraburg sands ?) f ^^ o 

 pierced by boring... J ^ 



B. 



Louvain. 



Thickness. 

 Feet. 



1. Diest sands 4 to 20 



2. Clay with Leda Des- 



hayesiana, &c. ... 2 to 10 



3. Sands with Middle 



Limburg fossils ... 40 



4. Brussels beds, or "I Un- 



Middle Eocene. J known. 



Bergh and Kleyn Spawen, 

 Limburg. 



Thickness. 

 Feet. 



1. Loess 15 



2. Nucula-loam with 



many Rupelmonde 

 fossils 3 



3. Sands and green marl 



(Middle Limburg). 56 



4. Lower fossiliferous 



Limburg beds with 

 Ostrea ventilabrum 20 



On comparing the accompanying three sections. A., B., and C, the 

 nature of the evidence in favour of considering the Rupelmonde clay to 

 be the equivalent of the Upper Limburg or " Nucula-loam " of Bergh, 

 near Kleyn Spawen, may be readily appreciated. It will be necessary 

 for the reader to bear in mind that the Louvain section, B., is geo- 

 graphically intermediate between A. and C. ; Louvain being only 

 twenty miles south-east of Rupelmonde, and forty miles west of Kleyn 

 Spawen. The identity of the clays No. 2 in A. and B. is shown 

 both by the similarity of their mineral character and contained sep- 

 taria, and by the presence of Leda Beshayesiana in abundance. The 

 intimate relation of the bed No. 2 in A. and C. is shown by the large 

 number of fossil species common to both, as before stated, p. 304. 



5. On the Loess near Kleyn Spawen, and on the Denudation of the 

 Limburg Tertiary strata. 



Before presenting the reader with a general Table of the Limburg 

 fossils, and with such observations as they suggest, I must say a few 

 words on the manner in which the Loess and associated alluviums 

 occur near Kleyn Spawen, sometimes putting on the appearance of 

 regular tertiary strata. 



■Section at Lethen near Bilsen, Limburg. 



Fig. 3.. 



Moulin de Lethen. 

 River Darner. 



D2 



A. Loess of the ordinary character. 

 D 2. Middle Limburg series. Upper part, green marl ; the lower, X, grey sand, and green 



clay and sand, unfossiliferous. 

 D 3. Lower Limburg beds. Sand with Ostrea ventilabrum. 

 a Greenish sandy clay. \ Modern alluvium. 

 « . Yellowish sandy clay. J 



Near Lethen, for example, the annexed section is seen on the slope 

 of the ground towards the valley of the Damer. When I first ex- 

 amined, with M. Bosquet, the beds, a, a, consisting of greenish clay 

 and sand, and containing Corbula pisum, Cerithium subcostellatum, 

 Cyrena semistriata, and many other Middle Limburg fossils, I sup- 



