[8 UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



considered the oldest Cretaceous outcrops in Limburg (the Heervian and the Aachen 

 sands) as belonging to the Middle Campanian. However, as her study was mainly 

 concerned with the Maestricht tuffaceous chalk, she could not precisely define the 

 lower boundary of the Maestrichtian. 



Jeletsky (1951), following Leriche (1927, 1929) and Schijfsma (1946) considered 



the Maestrichtian as " an independent stage younger than and equal in rank 



to the Senonian stage ....", while he considered the Campanian as the upper 

 substage of the Senonian. He stated that " The latest research of Abrard (1931 

 pp. 24-5 ; 1948 pp. 231, 233, 279-280) has, indeed, shown that at the type locality 

 of the Campanian stage in southwest France, near Champagne, the beds with 



Bostrychoceras polyplocum (Roemer) , were originally included in upper 



Campanian and not in lowermost Dordonian (an invalid synonym of Maestrichtian) ". 



Jeletzky's proposition was questioned by Van der Heide (1954) because it meant a 

 slight change of the Maestrichtian as originally defined by Dumont (1849). However, 

 as previously mentioned by Romein (1961, y e Colloque European de Micropaleontol- 

 ogie, Pays-Bas et Belgique, Guide d'Excursions, B. Upper Cretaceous, Limbourg : 

 1-3) the confusion and ambiguity of Dumont's definition of the term Maestrichtian, 

 led to the fact that the term has evolved through the times, independently from the 

 original definition of the type locality. The succession in the type area which is 

 known under the names of the tuffaceous limestone of Maestricht (Ma-Md) and the 

 Gulpen chalk (Cr 4 ) is generally considered to be of Upper Maestrichtian age (Meyer 

 1959 and Voigt i960). However, Romein (1962) extended the Maestrichtian in its 

 type area downwards to include most of the Gulpen chalk [Cr 3b (in part) — Cr 4 ], and 

 the Maestricht chalk (Ma-Me) which he partly equated with the Kunrade chalk. 



In 1959, the "Congres des Societes Savantes de Paris et des Departements" held at 

 Dijon, discussed the stratigraphical and palaeontological problems of the Upper 

 Cretaceous in France " Colloque sur le Cretace Superieur Francais ". In spite of 

 numerous disagreements, the congress came to the folio-wing conclusions : 



1. The Bostrychoceras polyplocum Zone which has always been assigned to the 



Lower Maestrichtian, is considered to be of Upper Campanian age. 



2. The Maestrichtian is limited to the zone of F 'achy 'discus neubergicus. 



3. Although strictly speaking the Maestrichtian should be excluded from the 



Senonian, it is generally admitted in France that the Upper Senonian 

 includes both the Campanain and the Maestrichtian ; being more practic- 

 able the committee proposed to continue this usage. 



However, until the type sections of the Senonian and Maestrichtian are studied in 

 detail and correlated more precisely, it is advisable to treat the Maestrichtian 

 separately from the Senonian. Thus in the present study, the Maestrichtian is 

 considered as an independent stage, younger than, and equal in rank to, the Senonian 

 stage as suggested by Jeletzky (1951), although it is clearly understood that the time 

 span represented by the Maestrictian is much shorter than that of the Senonian. 

 Again, the zone of Bostrycoceras polyplocum and its associated fauna which has been 



