Cycles of Sedimentation in the Eocene. 151 
an ill-defined band grading both upwards and downwards into fresh- 
water limestone. Stratigraphically, therefore, the creation of a 
separate stage seems unwarranted. Moreover, as Dollfust has shown, 
there are no really new elements in the Ludian fauna, at the most 
some variations from the typical forms of the Sables de Marines. 
It is important to note, however, that both Dollfus 2 and Leriche ® 
wish to include our Middle and Upper Headon Beds with the Eocene 
as part of the Bartonian (Leriche) = Marinesian of Dollfus. 
Now there is absolutely no doubt that the Bartonian Cycle closes 
with the Lower Headon. The Middle Headon Beds (including the 
Brockenhurst Beds) commence a fresh cycle. The classification of 
the French beds must depend on the age assigned to the Middle 
Headon Beds. At present the author is strongly inclined to agree 
with Boussac * that the Middle Headon Beds mark the base of the 
Oligocene, and that the Ludian is exactly equivalent to the Barton 
Sands (Long Mead End Beds). This agrees with the old opinion of 
von Koenen,° and with the more recent opinion of White,° that the 
lowest zone of the Middle Headon (Brockenhurst Zone) contains 
the most clearly marine fauna in the British Oligocene. The corre- 
lation therefore stands thus :-— 
Paris Basin. Hampshire. 
OLIGOCENE ; ; . | Marls above the | Middle Headon Beds 
Gypsum. (including Brocken- 
hurst Beds). 
Ludian . . | Ludian marls with | Lower Headon Beds 
EocENE— gypsum and Barton Sands 
Bartonian ) Bartonian Sands of Marines | Barton Clay. 
(sensu stricto) and Cresne 
It is only fair to state the other possible classification is as 
follows :— 
1 Dollfus, ‘‘ Excursion to Paris’’: Proc. Geol. Assoc., vol. xxi, 1909, p. 12. 
The writer is indebted to M. Dollfus for further unpublished information on 
this question. 
2 Dollfus, ““ On the Classification of the Beds of the Paris Basin’’: Proc. 
Geol. Assoc., vol. xxi, 1909, pp. 107-12. 
3 Leriche, “‘ Observations sur la Classification des Assises paléocénes et 
éocénes du Bassin de Paris’’: Ann. Soc. géol. Nord, vol. xxxiv, 1905, p. 391. 
* Boussac, ‘“‘ La Limite de l’Kocéne et de l’Oligocéne”’?: Bull. Soc. géol. 
France, sér. Iv, vol. vii, 1907, p. 400. 
° Von Koenen, ‘‘ Ueber diie Parallelisrung des norddeutschen, englischen, 
und franz6sischen Oligocins’’: Zeitsch. d.deutsch. geol.Gesells., 1867, pp. 23-32. 
° White, Geology of the Country near Lymington and Portsmouth (Mem. 
Geol. Surv.), 1915, p. 43. More recently White has adopted the correlation 
of Dollfuss (1909), Handb. Reg. Geol., Band iii, i Abt.: The British Isles, 
p. 272 (1917). 
